Proposed Rule2021-17496

Corporate Average Fuel Economy Standards for Model Years 2024-2026 Passenger Cars and Light Trucks

Primary source

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Published
September 3, 2021

Issuing agencies

Transportation DepartmentNational Highway Traffic Safety Administration

Abstract

NHTSA, on behalf of the Department of Transportation, is proposing revised fuel economy standards for passenger cars and light trucks for model years 2024-2026. On January 20, 2021, President Biden signed an Executive order (E.O.) entitled, "Protecting Public Health and the Environment and Restoring Science To Tackle the Climate Crisis." In it, the President directed that "The Safer Affordable Fuel-Efficient (SAFE) Vehicles Rule for Model Years 2021-2026 Passenger Cars and Light Trucks" (hereafter, "the 2020 final rule") be immediately reviewed for consistency with our Nation's abiding commitment to empower our workers and communities; promote and protect our public health and the environment; and conserve our national treasures and monuments, places that secure our national memory. President Biden further directed that the 2020 final rule be reviewed at once and that (in this case) the Secretary of Transportation consider "suspending, revising, or rescinding" it, via a new proposal, by July 2021. Because of the President's direction in the E.O., NHTSA reexamined the 2020 final rule under its authority to set corporate average fuel economy (CAFE) standards. In doing so, NHTSA tentatively concluded that the fuel economy standards set in 2020 should be revised so that they increase at a rate of 8 percent year over year for each model year from 2024 through 2026, for both passenger cars and light trucks. This responds to the agency's statutory mandate to improve energy conservation. This proposal also makes certain minor changes to fuel economy reporting requirements.

Full Text

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[Federal Register Volume 86, Number 169 (Friday, September 3, 2021)]
[Proposed Rules]
[Pages 49602-49883]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2021-17496]



[[Page 49601]]

Vol. 86

Friday,

No. 169

September 3, 2021

Part II





Department of Transportation





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 National Highway Traffic Safety Administration





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49 CFR Parts 531, 533 et al.





Corporate Average Fuel Economy Standards for Model Years 2024-2026 
Passenger Cars and Light Trucks; Proposed Rule

Federal Register / Vol. 86, No. 169 / Friday, September 3, 2021 / 
Proposed Rules

[[Page 49602]]


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DEPARTMENT OF TRANSPORTATION

National Highway Traffic Safety Administration

49 CFR Parts 531, 533, 536, and 537

[NHTSA-2021-0053]
RIN 2127-AM34


Corporate Average Fuel Economy Standards for Model Years 2024-
2026 Passenger Cars and Light Trucks

AGENCY: National Highway Traffic Safety Administration (NHTSA), 
Department of Transportation (DOT).

ACTION: Notice of proposed rulemaking.

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SUMMARY: NHTSA, on behalf of the Department of Transportation, is 
proposing revised fuel economy standards for passenger cars and light 
trucks for model years 2024-2026. On January 20, 2021, President Biden 
signed an Executive order (E.O.) entitled, ``Protecting Public Health 
and the Environment and Restoring Science To Tackle the Climate 
Crisis.'' In it, the President directed that ``The Safer Affordable 
Fuel-Efficient (SAFE) Vehicles Rule for Model Years 2021-2026 Passenger 
Cars and Light Trucks'' (hereafter, ``the 2020 final rule'') be 
immediately reviewed for consistency with our Nation's abiding 
commitment to empower our workers and communities; promote and protect 
our public health and the environment; and conserve our national 
treasures and monuments, places that secure our national memory. 
President Biden further directed that the 2020 final rule be reviewed 
at once and that (in this case) the Secretary of Transportation 
consider ``suspending, revising, or rescinding'' it, via a new 
proposal, by July 2021. Because of the President's direction in the 
E.O., NHTSA reexamined the 2020 final rule under its authority to set 
corporate average fuel economy (CAFE) standards. In doing so, NHTSA 
tentatively concluded that the fuel economy standards set in 2020 
should be revised so that they increase at a rate of 8 percent year 
over year for each model year from 2024 through 2026, for both 
passenger cars and light trucks. This responds to the agency's 
statutory mandate to improve energy conservation. This proposal also 
makes certain minor changes to fuel economy reporting requirements.

DATES: Comments: Comments are requested on or before October 26, 2021. 
In compliance with the Paperwork Reduction Act, NHTSA is also seeking 
comment on a revision to an existing information collection. For 
additional information, see the Paperwork Reduction Act Section under 
Section IX, below. All comments relating to the information collection 
requirements should be submitted to NHTSA and to the Office of 
Management and Budget (OMB) at the address listed in the ADDRESSES 
section on or before October 26, 2021. See the SUPPLEMENTARY 
INFORMATION section on ``Public Participation,'' below, for more 
information about written comments.
    Public Hearings: NHTSA will hold one virtual public hearing during 
the public comment period. The agency will announce the specific date 
and web address for the hearing in a supplemental Federal Register 
notification. The agency will accept oral and written comments on the 
rulemaking documents and will also accept comments on the Supplemental 
Environmental Impact Statement (SEIS) at this hearing. The hearing will 
start at 9 a.m. Eastern standard time and continue until everyone has 
had a chance to speak. See the SUPPLEMENTARY INFORMATION section on 
``Public Participation,'' below, for more information about the public 
hearing.

ADDRESSES: You may send comments, identified by Docket No. NHTSA-2021-
0053, by any of the following methods:
    <bullet> Federal eRulemaking Portal: <a href="http://www.regulations.gov">http://www.regulations.gov</a>. 
Follow the instructions for submitting comments.
    <bullet> Fax: (202) 493-2251.
    <bullet> Mail: Docket Management Facility, M-30, U.S. Department of 
Transportation, West Building, Ground Floor, Rm. W12-140, 1200 New 
Jersey Avenue SE, Washington, DC 20590.
    <bullet> Hand Delivery: Docket Management Facility, M-30, U.S. 
Department of Transportation, West Building, Ground Floor, Rm. W12-140, 
1200 New Jersey Avenue SE, Washington, DC 20590, between 9 a.m. and 4 
p.m. Eastern Time, Monday through Friday, except Federal holidays.
    Comments on the proposed information collection requirements should 
be submitted to: Office of Management and Budget at <a href="http://www.reginfo.gov/public/do/PRAMain">www.reginfo.gov/public/do/PRAMain</a>. To find this particular information collection, 
select ``Currently under Review--Open for Public Comment'' or use the 
search function. NHTSA requests that comments sent to the OMB also be 
sent to the NHTSA rulemaking docket identified in the heading of this 
document.
    Instructions: All submissions received must include the agency name 
and docket number or Regulatory Information Number (RIN) for this 
rulemaking. All comments received will be posted without change to 
<a href="http://www.regulations.gov">http://www.regulations.gov</a>, including any personal information 
provided. For detailed instructions on sending comments and additional 
information on the rulemaking process, see the ``Public Participation'' 
heading of the SUPPLEMENTARY INFORMATION section of this document.
    Docket: For access to the dockets or to read background documents 
or comments received, please visit <a href="http://www.regulations.gov">http://www.regulations.gov</a>, and/or 
Docket Management Facility, M-30, U.S. Department of Transportation, 
West Building, Ground Floor, Rm. W12-140, 1200 New Jersey Avenue SE, 
Washington, DC 20590. The Docket Management Facility is open between 9 
a.m. and 4 p.m. Eastern Time, Monday through Friday, except Federal 
holidays.

FOR FURTHER INFORMATION CONTACT: Rebecca Schade, NHTSA Office of Chief 
Counsel, National Highway Traffic Safety Administration, 1200 New 
Jersey Avenue SE, Washington, DC 20590; email: <a href="/cdn-cgi/l/email-protection#27554245424444460954444f4643426743485309404851"><span class="__cf_email__" data-cfemail="6a180f080f09090b441909020b0e0f2a0e051e440d051c">[email&#160;protected]</span></a>.

SUPPLEMENTARY INFORMATION:

Does this action apply to me?

    This action affects companies that manufacture or sell new 
passenger automobiles (passenger cars) and non-passenger automobiles 
(light trucks) as defined under NHTSA's CAFE regulations.\1\ Regulated 
categories and entities include:
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    \1\ ``Passenger car'' and ``light truck'' are defined in 49 CFR 
part 523.

[[Page 49603]]



------------------------------------------------------------------------
                                  NAICS  Codes   Examples of potentially
            Category                   \A\          regulated entities
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Industry.......................          335111  Motor Vehicle
                                                  Manufacturers.
                                         336112
Industry.......................          811111  Commercial Importers of
                                                  Vehicles and Vehicle
                                                  Components.
                                         811112
                                         811198
                                         423110
Industry.......................          335312  Alternative Fuel
                                                  Vehicle Converters.
                                         336312
                                         336399
                                         811198
------------------------------------------------------------------------
\A\ North American Industry Classification System (NAICS).

    This list is not intended to be exhaustive, but rather provides a 
guide regarding entities likely to be regulated by this action. To 
determine whether particular activities may be regulated by this 
action, you should carefully examine the regulations. You may direct 
questions regarding the applicability of this action to the person 
listed in FOR FURTHER INFORMATION CONTACT.

I. Executive Summary

    NHTSA, on behalf of the Department of Transportation, is proposing 
to amend standards regulating corporate average fuel economy (CAFE) for 
passenger cars and light trucks for model years (MYs) 2024-2026. This 
proposal responds to NHTSA's statutory obligation to set maximum 
feasible CAFE standards to improve energy conservation, and to 
President Biden's directive in Executive Order 13990 of January 20, 
2021 that ``The Safer Affordable Fuel-Efficient (SAFE) Vehicles Rule 
for Model Years 2021-2026 Passenger Cars and Light Trucks'', 2020 final 
rule or 2020 CAFE rule (85 FR 24174 (April 30, 2020)), be immediately 
reviewed for consistency with our Nation's abiding commitment to 
promote and protect our public health and the environment, among other 
things. NHTSA undertook that review immediately, and this proposal is 
the result of that process.
    The proposed amended CAFE standards would increase in stringency 
from MY 2023 levels by 8 percent per year, for both passenger cars and 
light trucks over MYs 2024-2026. NHTSA tentatively concludes that this 
level is maximum feasible for these model years, as discussed in more 
detail in Section VI, and seeks comment on that conclusion. The 
proposal considers a range of regulatory alternatives, consistent with 
NHTSA's obligations under the National Environmental Policy Act (NEPA) 
and Executive Order 12866. While E.O. 13990 directed the review of CAFE 
standards for MYs 2021-2026, statutory lead time requirements mean that 
the soonest model year that can currently be amended in the CAFE 
program is MY 2024. The proposed standards would remain vehicle 
footprint-based, like the CAFE standards in effect since MY 2011. 
Recognizing that many readers think about CAFE standards in terms of 
the miles per gallon (mpg) values that the standards are projected to 
eventually require, NHTSA currently projects that the proposed 
standards would require, on an average industry fleet-wide basis, 
roughly 48 mpg in MY 2026. NHTSA notes both that real-world fuel 
economy is generally 20-30 percent lower than the estimated required 
CAFE level stated above, and also that the actual CAFE standards are 
the footprint target curves for passenger cars and light trucks, 
meaning that ultimate fleet-wide levels will vary depending on the mix 
of vehicles that industry produces for sale in those model years. Table 
I-1 shows the incremental differences in stringency levels for 
passenger cars and light trucks, by regulatory alternative, in the 
model years subject to regulation.
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    This proposal is significantly different from the conclusion that 
NHTSA reached in the 2020 final rule, but this is because important 
facts have changed, and because NHTSA has reconsidered how to balance 
the relevant statutory considerations in light of those facts. NHTSA 
tentatively concludes that significantly more stringent standards are 
maximum feasible. Contrary to the 2020 final rule, NHTSA recognizes 
that the need of the United States to conserve energy must include 
serious consideration of the energy security risks of continuing to 
consume oil, which more stringent fuel economy standards can reduce. 
Reducing our Nation's climate impacts can also benefit our national 
security. Additionally, at least part of the automobile industry 
appears increasingly convinced that improving fuel economy and reducing 
greenhouse gas (GHG) emissions is a growth market for them, and that 
the market rewards investment in advanced technology. Nearly all auto 
manufacturers have announced forthcoming new higher fuel-economy and 
electric vehicle models, and five major manufacturers voluntarily bound 
themselves to stricter GHG requirements than set forth by NHTSA and the 
Environmental Protection Agency (EPA) in 2020 through contractual 
agreements with the State of California, which will result in their 
achieving fuel economy levels well above the standards set forth in the 
2020 final rule. These companies are sophisticated, for-profit 
enterprises. If they are taking these steps, NHTSA can be more 
confident than the agency was in 2020 that the market is getting ready 
to make the leap to significantly higher fuel economy. The California 
Framework and the clear planning by industry to migrate toward more 
advanced fuel economy technologies are evidence of the practicability 
of more stringent standards. Moreover, more stringent CAFE standards 
will help to encourage industry to continue improving the fuel economy 
of all vehicles, rather than simply producing a few electric vehicles, 
such that all Americans can benefit from higher fuel economy and save 
money on fuel. NHTSA cannot consider the fuel economy of dedicated 
alternative fuel vehicles like battery electric vehicles when 
determining maximum feasible standards, but the fact that industry 
increasingly appears to believe that there is a market for these 
vehicles is broader evidence of market (and consumer) interest in fuel 
economy, which is relevant to NHTSA's determination of whether more 
stringent standards would be economically practicable. For all of these 
reasons, NHTSA tentatively concludes that standards that increase at 8 
percent per year are maximum feasible.
    This proposal is also different from the 2020 final rule in that it 
is issued by NHTSA alone, and EPA has issued a separate proposal. The 
primary reason for this is the difference in statutory authority--EPA 
does not have the same lead time requirements as NHTSA and is thus able 
to amend MY 2023 in addition to MYs 2024-2026. An important consequence 
of this is that EPA's proposed rate of stringency increase, after 
taking a big leap in MY 2023, looks slower than NHTSA's over the same 
time period. NHTSA emphasizes, however, that the proposed standards are 
what NHTSA believes best fulfills our statutory directive of energy 
conservation, and in the context of the EPA standards, the analysis we 
have done is tackling the core question of whether compliance with both 
standards should be achievable with the same vehicle fleet, after 
manufacturers fully understand the requirements from both proposals. 
The differences in what the two agencies' standards require become 
smaller each year, until alignment is achieved. While NHTSA recognizes 
that the last several CAFE standard rulemakings have been issued 
jointly with EPA, and that issuing separate proposals represents a 
change in approach, the agencies worked together to avoid 
inconsistencies and to create proposals that would continue to allow 
manufacturers to build a single fleet of vehicles to meet both 
agencies' proposed standards. Additionally, and importantly, NHTSA has 
also considered and accounted for California's Zero Emission Vehicle 
(ZEV) program (and its adoption by a number of other states) in 
developing the baseline for this proposal, and has accounted for the 
aforementioned ``Framework Agreements'' between California and BMW, 
Ford, Honda, Volkswagen of America (VWA), and Volvo, which are 
national-level GHG standards to which these companies committed for 
several model years.
    A number of other improvements and updates have been made to the 
analysis since the 2020 final rule. Table I-2 summarizes these, and 
they are discussed in much more detail below and in the documents 
accompanying this preamble.
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BILLING CODE 4910-59-C
    NHTSA estimates that this proposal could reduce average 
undiscounted fuel outlays over the lifetimes of MY 2029 vehicles by 
about $1,280, while increasing the average cost of those vehicles by 
about $960 over the baseline described above. With the social cost of 
carbon (SCC) discounted at 2.5 percent and other benefits and costs 
discounted at 3 percent, for the three affected model years NHTSA finds 
$65.8 billion in benefits attributable to the proposed standards and 
$37.4 billion in proposed costs so that present net benefits could be 
$28.4 billion.\2\ Applied to the entire fleet for MYs 1981-2029, NHTSA 
estimates $120 billion in costs and $121

[[Page 49606]]

billion in benefits attributable to the proposed standards, such that 
the present value of aggregate net benefits to society could be $1 
billion. Like any analysis of this magnitude attempting to forecast 
future effects of current policies, significant uncertainty exists 
about many key inputs. Changes in the price of fuel or in the social 
cost of carbon could dramatically change benefits, for example, and 
readers should expect that the eventual final rule will reflect any 
updates made to those (and many other) values that occur between now 
and then. It is also worth stressing that NHTSA's statutory authority 
requires that its standards be maximum feasible, taking into account 
four statutory factors. While NHTSA's estimates of costs and benefits 
are important considerations, it is the maximum feasible analysis that 
controls the setting of CAFE standards.
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    \2\ As discussed in Section III.G.2.b), NHTSA has discounted the 
SCC at 2.5% when other benefits and costs are discounted at 3% but 
seeks comment on this approach.
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    Like many other types of regulations, CAFE standards apply only to 
new vehicles. The costs attributable to new CAFE standards are thus 
``front-loaded,'' because they result primarily from the application of 
fuel-saving technology to new vehicles. On the other hand, the impact 
of new CAFE standards on fuel consumption and greenhouse gases--and the 
associated benefits to society--occur over an extended time, as drivers 
buy, use, and eventually scrap these new vehicles. By accounting for 
many model years and extending well into the future (2050), our 
analysis accounts for these differing patterns in impacts, benefits, 
and costs. Our analysis also accounts for the potential that, by 
changing new vehicle prices and fuel economy levels, CAFE standards 
could indirectly impact the operation of vehicles produced before or 
after the model years (2024-2026) for which we are proposing new CAFE 
standards. This means that some of the proposal's impacts and 
corresponding benefits and costs are actually attributable to indirect 
impacts on vehicles produced before and after model years 2024-2026.
    The bulk of our analysis considers a ``model year'' (MY) 
perspective that considers the lifetime impacts attributable to all 
vehicles produced prior to model year 2030, accounting for the 
operation of these vehicles over their entire useful lives (with some 
model year 2029 vehicles estimated to be in service as late as 2068). 
This approach emphasizes the role of model years 2024-2026, while 
accounting for the potential that it may take manufacturers a few 
additional years to produce fleets fully responsive to the proposed MY 
2026 standards, and for the potential that the proposal could induce 
some changes in the operation of vehicles produced prior to MY 2024.
    Our analysis also considers a ``calendar year'' (CY) perspective 
that includes the annual impacts attributable to all vehicles estimated 
to be in service in each calendar year for which our analysis includes 
a representation of the entire registered light-duty fleet. For this 
NPRM, this calendar year perspective covers each of calendar years 
2021-2050, with differential impacts accruing as early as model year 
2023. Compared to the ``model year'' perspective, this calendar year 
perspective emphasizes model years of vehicles produced in the longer 
term, beyond those model years for which standards are currently being 
proposed. Table I-3 summarizes estimates of selected physical impacts 
viewed from each of these two perspectives, as well as corresponding 
estimates of the present values of cumulative benefits, costs, and net 
benefits.
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    Finally, for purposes of comparing the benefits and costs of new 
CAFE standards to the benefits and costs of other Federal regulations, 
policies, and programs, we have computed ``annualized'' benefits and 
costs. These are the annual averages of the cumulative benefits and 
costs over the covered model or calendar years, after expressing these 
in present value terms.
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    As discussed in detail below, the monetized estimated costs and 
benefits of this proposal are relevant and important to the agency's 
tentative conclusion, but they are not the whole of the conclusion.

[[Page 49609]]

    Additionally, although NHTSA is prohibited from considering the 
availability of certain flexibilities in making our determination about 
the levels of CAFE standards that would be maximum feasible, 
manufacturers have a variety of flexibilities available to them to 
reduce their compliance burden. Table I-10 through Table I-13 below 
summarizes available compliance flexibilities. NHTSA seeks comment on 
whether to retain non-statutory flexibilities for the final rule.
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BILLING CODE 4910-59-C
    NHTSA recognizes that the lead time for this proposal is shorter 
than past rulemakings have provided, and that the economy and the 
country are in the process of recovering from a global pandemic and the 
resulting economic distress. At the same time, NHTSA also recognizes 
that at least parts of the industry are nonetheless stepping up their 
product offerings and releasing more and more high fuel-economy vehicle 
models, and many companies did not deviate significantly from product 
plans established in response to the standards set forth in the 2012 
final rule (77 FR 62624, Oct. 15, 2012) and confirmed by EPA in its 
January 2017 Final Determination. With these considerations in mind, 
NHTSA is proposing to amend the CAFE standards for MYs 2024-2026. 
NHTSA, like any other Federal agency, is afforded an opportunity to 
reconsider prior views and, when warranted, to adopt new positions. 
Indeed, as a matter of good governance, agencies should revisit their 
positions when appropriate, especially to ensure that their actions and 
regulations reflect legally sound interpretations of the agency's 
authority and remain consistent with the agency's views and practices. 
As a matter of law, ``an Agency is entitled to change its 
interpretation of a statute.'' \3\ Nonetheless, ``[w]hen an Agency 
adopts a materially changed interpretation of a statute, it must in 
addition provide a `reasoned analysis' supporting its decision to 
revise its interpretation.'' \4\ The analysis presented in this 
preamble and in the accompanying Technical Support Document (TSD), 
Preliminary Regulatory Impact Analysis (PRIA), Supplemental 
Environmental Impact Statement (SEIS), CAFE Model documentation, and 
extensive rulemaking docket fully supports the proposed decision and 
revised balancing of the statutory factors for MYs 2024-2026 standards. 
NHTSA seeks comment on the entirety of the rulemaking record.
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    \3\ Phoenix Hydro Corp. v. FERC, 775 F.2d 1187, 1191 (D.C. Cir. 
1985).
    \4\ Alabama Educ. Ass'n v. Chao, 455 F.3d 386, 392 (D.C. Cir. 
2006) (quoting Motor Vehicle Mfrs. Ass'n of U.S., Inc. v. State Farm 
Mut. Auto. Ins. Co., 463 U.S. 29, 57 (1983)); see also Encino 
Motorcars, LLC v. Navarro, 136 S.Ct. 2117, 2125 (2016) (``Agencies 
are free to change their existing policies as long as they provide a 
reasoned explanation for the change.'') (citations omitted).
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II. Introduction

    In this notice of proposed rulemaking (NPRM), NHTSA is proposing to 
revise CAFE standards for model years (MYs) 2024-2026. On January 20, 
2021, the President signed Executive Order (E.O.) 13990, ``Protecting 
Public Health and the Environment and Restoring Science To Tackle the 
Climate Crisis.'' \5\ In it, the President directed that ``The Safer 
Affordable Fuel-Efficient (SAFE) Vehicles Rule for Model Years 2021-
2026 Passenger Cars and Light Trucks'' (hereafter, ``the 2020 final 
rule''), 85 FR 24174 (April 30, 2020), must be immediately reviewed for 
consistency with our Nation's abiding commitment to empower our workers 
and communities; promote and protect our public health and the 
environment; and conserve our national treasures and monuments, places 
that secure our national memory. E.O. 13990 states expressly that the 
Administration prioritizes listening to the science, improving public 
health and protecting the environment, reducing greenhouse gas 
emissions, and improving environmental justice while creating well-
paying union jobs. The E.O. thus directs that the 2020 final rule be 
reviewed at once and that (in this case) the Secretary of 
Transportation consider ``suspending, revising, or rescinding'' it, via 
an NPRM, by July 2021.\6\
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    \5\ 86 FR 7037 (Jan. 25, 2021).
    \6\ Id., Sec. 2(a)(ii).
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    Section 32902(g)(1) of Title 49, United States Code allows the 
Secretary (by delegation to NHTSA) to prescribe regulations amending an 
average fuel economy standard prescribed under 49 U.S.C. 32902(a), like 
those prescribed in the 2020 final rule, if the amended standard meets 
the requirements of 32902(a). The Secretary's authority to set fuel 
economy standards is delegated to NHTSA at 49 CFR 1.95(a); therefore, 
in this NPRM, NHTSA proposes revised fuel economy standards for MYs 
2024-2026. Section 32902(g)(2) states that when the amendment makes an 
average fuel economy standard more stringent, it must be prescribed at 
least 18 months before the beginning of the model year to which the 
amendment applies. NHTSA generally calculates the 18-month lead time 
requirement as April of the calendar year prior to the start of the 
model year. Thus, 18 months before MY 2023 would be April 2021, because 
MY 2023 begins in September 2022. Because of this lead time 
requirement, NHTSA is not proposing to amend the CAFE standards for MYs 
2021-2023, even though the 2020 final rule also covered those model 
years. For purposes of the CAFE program, the 2020 final rule's 
standards for MYs 2021-2023 will remain in effect.
    For the MYs for which there is statutory lead time to amend the 
standards, however, NHTSA is proposing amendments to the currently 
applicable fuel economy standards. Although only one year has passed 
since the 2020 final rule, the agency believes it is reasonable and 
appropriate to revisit the CAFE standards for MYs 2024-2026. In 
particular, the agency has further considered the serious adverse 
effects on energy conservation that the standards finalized in 2020 
would cause

[[Page 49611]]

as compared to the proposed standards. The need of the U.S. to conserve 
energy is greater than understood in the 2020 final rule. In addition, 
standards that are more stringent than those that were finalized in 
2020 appear economically practicable. Nearly all auto manufacturers 
have announced forthcoming new advanced technology vehicle models with 
higher fuel economy, making strong public commitments that mirror those 
of the Administration. Five major manufacturers voluntarily bound 
themselves to stricter national-level GHG requirements as part of the 
California Framework agreement. Meanwhile, certain facts on the ground 
remain similar to what was before NHTSA in the prior analysis--gas 
prices still remain relatively low in the U.S., for example, and while 
light-duty vehicle sales fell sharply in MY 2020, the vehicles that did 
sell tended to be, on average, larger, heavier, and more powerful, all 
factors that increase fuel consumption. However, the renewed focus on 
addressing energy conservation and the industry's apparent ability to 
meet more stringent standards show that a rebalancing of the EPCA 
factors, and the proposal of more stringent standards, is appropriate 
for model years 2024-2026.
    The following sections introduce the proposal in more detail.

A. What is NHTSA proposing?

    NHTSA is proposing to set CAFE standards for passenger cars and 
light trucks manufactured for sale in the United States in MYs 2024-
2026. Passenger cars are generally sedans, station wagons, and two-
wheel drive crossovers and sport utility vehicles (CUVs and SUVs), 
while light trucks are generally four-wheel drive vehicles, larger/
heavier two-wheel drive sport utility vehicles, pickups, minivans, and 
passenger/cargo vans.\7\ The proposed standards would increase at 8 
percent per year for both cars and trucks, and are represented by 
regulatory Alternative 2 in the agency's analysis. The proposed 
standards would be defined by a mathematical equation that represents a 
constrained linear function relating vehicle footprint to fuel economy 
targets for both cars and trucks; vehicle footprint is roughly measured 
as the rectangle that is made by the four points where the vehicle's 
tires touch the ground. Generally, passenger cars will have more 
stringent targets than light trucks regardless of footprint, and 
smaller vehicles will have more stringent targets than larger vehicles. 
No individual vehicle or vehicle model need meet its target exactly, 
but a manufacturer's compliance is determined by how its average fleet 
fuel economy compares to the average fuel economy of the targets of the 
vehicles it manufactures.
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    \7\ ``Passenger car'' and ``light truck'' are defined at 49 CFR 
part 523.
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    The proposed target curves \8\ for passenger cars and light trucks 
are as follows; curves for MYs 2020-2023 are included in Figure II-1 
and Figure II-2 for context.
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    \8\ NHTSA underscores that the equations and coefficients 
defining the curves are what the agency is proposing, and not the 
mpg numbers that the agency currently estimates could result from 
manufacturers complying with the curves. Because the estimated mpg 
numbers are an effect of the proposed curves, they are presented in 
the following section.
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BILLING CODE 4910-59-C
    NHTSA is also proposing to amend the minimum domestic passenger car 
CAFE standards for MYs 2024-2026. The provision at 49 U.S.C. 
32902(b)(4) requires NHTSA to project the minimum standard when it 
promulgates passenger car standards for a model year, so it is 
appropriate to revisit the minimum standards at this time. NHTSA is 
proposing to retain the 1.9 percent offset used in the 2020 final rule, 
such that the minimum domestic passenger car standard would be as shown 
in Table II-1.
[GRAPHIC] [TIFF OMITTED] TP03SE21.015

    The next section describes some of the effects that NHTSA estimates 
would follow from this proposal, including how the curves shown above 
translate to estimated average mile per gallon requirements for the 
industry.

B. What does NHTSA estimate the effects of proposing this would be?

    As for past CAFE rulemakings, NHTSA has used the CAFE Model to 
estimate the effects of proposed CAFE standards, and of other 
regulatory alternatives under consideration. Some inputs to the CAFE 
Model are derived from other models, such as Argonne National 
Laboratory's ``Autonomie'' vehicle simulation tool and Argonne's 
Greenhouse gases, Regulated Emissions, and Energy use in Transportation 
(GREET) fuel-cycle emissions analysis model, the U.S. Energy 
Information Administration's (EIA's) National Energy Modeling System 
(NEMS), and EPA's Motor Vehicle Emission Simulator (MOVES) vehicle 
emissions model. Especially given the scope of the

[[Page 49614]]

NHTSA's analysis (through model years 2050, with driving of model year 
2029 vehicles accounted for through calendar year 2068), these inputs 
involve a multitude of uncertainties. For example, a set of inputs with 
significant uncertainty could include future population and economic 
growth, future gasoline and electricity prices, future petroleum market 
characteristics (e.g., imports and exports), future battery costs, 
manufacturers' future responses to standards and fuel prices, buyers' 
future responses to changes in vehicle prices and fuel economy levels, 
and future emission rates for ``upstream'' processes (e.g., refining, 
finished fuel transportation, electricity generation). Considering that 
all of this is uncertain from a 2021 vantage point, NHTSA underscores 
that all results of this analysis are, in turn, uncertain, and simply 
represent the agency's best estimates based on the information 
currently before us.
    NHTSA estimates that this proposal would increase the eventual \9\ 
average of manufacturers' CAFE requirements to about 48 mpg by 2026 
rather than, under the No-Action Alternative (i.e., the baseline 
standards issued in 2020), about 40 mpg. For passenger cars, the 
average in 2026 is estimated to reach about 58 mpg, and for light 
trucks, about 42. This compares with 47 mpg and 34 mpg for cars and 
trucks, respectively, under the No-Action Alternative.
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    \9\ Here, ``eventual'' means by MY 2029, after most of the fleet 
will have been redesigned under the MY 2026 standards. NHTSA allows 
the CAFE Model to continue working out compliance solutions for the 
regulated model years for three model years after the last regulated 
model year, in recognition of the fact that manufacturers do not 
comply perfectly with CAFE standards in each model year.
[GRAPHIC] [TIFF OMITTED] TP03SE21.016

    Because manufacturers do not comply exactly with each standard in 
each model year, but rather focus their compliance efforts when and 
where it is most cost-effective to do so, ``estimated achieved'' fuel 
economy levels differ somewhat from ``estimated required'' levels for 
each fleet, for each year. NHTSA estimates that the industry-wide 
average fuel economy achieved in MY 2029 could increase from about 44 
mpg under the No-Action Alternative to about 49 mpg under the proposal.
[GRAPHIC] [TIFF OMITTED] TP03SE21.017

    As discussed above, NHTSA's analysis--unlike its previous CAFE 
analyses--estimates manufacturers' potential responses to the combined 
effect of CAFE standards and separate CO<INF>2</INF> standards 
(including agreements some manufacturers have reached with California), 
ZEV mandates, and fuel prices. Together, the aforementioned regulatory 
programs are more binding than any single program considered in 
isolation, and this analysis, like past analyses, shows some estimated 
overcompliance with the proposed CAFE standards, albeit by much less 
than what was shown in the NPRM that preceded the 2020 final rule, and 
any overcompliance is highly manufacturer-dependent.
    Expressed as equivalent required and achieved average 
CO<INF>2</INF> levels (using 8887 grams of CO<INF>2</INF> per gallon of 
gasoline vehicle certification fuel), the above CAFE levels appear as 
shown in Table II-4 and Table II-5.
[GRAPHIC] [TIFF OMITTED] TP03SE21.018


[[Page 49615]]


[GRAPHIC] [TIFF OMITTED] TP03SE21.019

    Average requirements and achieved CAFE levels would ultimately 
depend on manufacturers' and consumers' responses to standards, 
technology developments, economic conditions, fuel prices, and other 
factors.
    NHTSA estimates that over the lives of vehicles produced prior to 
MY 2030, the proposal would save about 50 billion gallons of gasoline 
and increase electricity consumption (as the percentage of electric 
vehicles increases over time) by about 275 terawatts (TWh), compared to 
levels of gasoline and electricity consumption NHTSA projects would 
occur under the baseline standards (i.e., the No-Action Alternative).
[GRAPHIC] [TIFF OMITTED] TP03SE21.020

    NHTSA's analysis also estimates total annual consumption of fuel by 
the entire on-road fleet from calendar year 2020 through calendar year 
2050. On this basis, gasoline and electricity consumption by the U.S. 
light-duty vehicle fleet evolves as shown in Figure II-3 and Figure II-
4, each of which shows projections for the No-Action Alternative 
(Alternative 0, i.e., the baseline), Alternative 1, Alternative 2 (the 
proposal), and Alternative 3.
BILLING CODE 4910-59-P

[[Page 49616]]

[GRAPHIC] [TIFF OMITTED] TP03SE21.021


[[Page 49617]]


[GRAPHIC] [TIFF OMITTED] TP03SE21.022

    Accounting for emissions from both vehicles and upstream energy 
sector processes (e.g., petroleum refining and electricity generation), 
NHTSA estimates that the proposal would reduce greenhouse gas emissions 
by about 465 million metric tons of carbon dioxide (CO<INF>2</INF>), 
about 500 thousand metric tons of methane (CH<INF>4</INF>), and about 
12 thousand tons of nitrous oxide (N<INF>2</INF>O).
[GRAPHIC] [TIFF OMITTED] TP03SE21.023

    As for fuel consumption, NHTSA's analysis also estimates annual 
emissions attributable to the entire on-road fleet from calendar year 
2020 through calendar year 2050. Also accounting for both vehicles and 
upstream processes, NHTSA estimates that CO<INF>2</INF> emissions could 
evolve over time as shown in Figure II-5, which accounts for both 
emissions from both vehicles and upstream processes.

[[Page 49618]]

[GRAPHIC] [TIFF OMITTED] TP03SE21.024

    Estimated emissions of methane and nitrous oxides follow similar 
trends. As discussed in the TSD, PRIA, and this NPRM, NHTSA has 
performed two types of supporting analysis. This NPRM and PRIA focus on 
the ``standard setting'' analysis, which sets aside the potential that 
manufacturers could respond to standards by using compliance credits or 
introducing new alternative fuel vehicle (including BEVs) models during 
the ``decision years'' (for this NPRM, 2024, 2025, and 2026). The 
accompanying SEIS focuses on an ``unconstrained'' analysis, which does 
not set aside these potential manufacturer actions. The SEIS presents 
much more information regarding projected GHG emissions, as well as 
model-based estimates of corresponding impacts on several measures of 
global climate change.
    Also accounting for vehicular and upstream emissions, NHTSA has 
estimated annual emissions of most criteria pollutants (i.e., 
pollutants for which EPA has issued National Ambient Air Quality 
Standards). NHTSA estimates that under each regulatory alternative, 
annual emissions of carbon monoxide (CO), volatile organic compounds 
(VOC), nitrogen oxide (NO<INF>X</INF>), and fine particulate matter 
(PM<INF>2.5</INF>) attributable to the light-duty on-road fleet will 
decline dramatically between 2020 and 2050, and that emissions in any 
given year could be very nearly the same under each regulatory 
alternative. For example, Figure II-6 shows NHTSA's estimate of future 
NO<INF>X</INF> emissions under each alternative.

[[Page 49619]]

[GRAPHIC] [TIFF OMITTED] TP03SE21.025

BILLING CODE 4910-59-C
    On the other hand, as discussed in the PRIA and SEIS, NHTSA 
projects that annual SO<INF>2</INF> emissions attributable to the 
light-duty on-road fleet could increase modestly under the action 
alternatives, because, as discussed above, NHTSA projects that each of 
the action alternatives could lead to greater use of electricity (for 
PHEVs and BEVs). The adoption of actions--such as actions prompted by 
President Biden's Executive order directing agencies to develop a 
Federal Clean Electricity and Vehicle Procurement Strategy--to reduce 
electricity generation emission rates beyond projections underlying 
NHTSA's analysis (discussed in the TSD) could dramatically reduce 
SO<INF>2</INF> emissions under all regulatory alternatives considered 
here.\10\
---------------------------------------------------------------------------

    \10\ <a href="https://www.whitehouse.gov/briefing-room/presidential-actions/2021/01/27/executive-order-on-tackling-the-climate-crisis-at-home-and-abroad/">https://www.whitehouse.gov/briefing-room/presidential-actions/2021/01/27/executive-order-on-tackling-the-climate-crisis-at-home-and-abroad/</a>, accessed June 17, 2021.
---------------------------------------------------------------------------

    For the ``standard setting'' analysis, the PRIA accompanying this 
NPRM provides additional detail regarding projected criteria pollutant 
emissions and health effects, as well as the inclusion of these impacts 
in this benefit-cost analysis. For the ``unconstrained'' or ``EIS'' 
type of analysis, the SEIS accompanying this NPRM presents much more 
information regarding projected criteria pollutant emissions, as well 
as model-based estimates of corresponding impacts on several measures 
of urban air quality and public health. As mentioned above, these 
estimates of criteria pollutant emissions are based on a complex 
analysis involving interacting simulation techniques and a myriad of 
input estimates and assumptions. Especially extending well past 2040, 
the analysis involves a multitude of uncertainties. Therefore, actual 
criteria pollutant emissions could ultimately be different from NHTSA's 
current estimates.
    To illustrate the effectiveness of the technology added in response 
to this proposal, Table II-8 presents NHTSA's estimates for increased 
vehicle cost and lifetime fuel expenditures if we assumed the 
behavioral response to the lower cost of driving were zero.\11\ These 
numbers are presented in lieu of NHTSA's primary estimate of lifetime 
fuel savings, which would give an incomplete picture of technological 
effectiveness because the analysis accounts for consumers' behavioral 
response to the lower cost-per-mile of driving a more fuel-efficient 
vehicle.
---------------------------------------------------------------------------

    \11\ While this comparison illustrates the effectiveness of the 
technology added in response to this proposal, it does not represent 
a full consumer welfare analysis, which would account for drivers' 
likely response to the lower cost-per-mile of driving, as well as a 
variety of other benefits and costs they will experience. The 
agency's complete analysis of the proposal's likely impacts on 
passenger car and light truck buyers appears in the PRIA, Appendix 
I, Table A-23-1.

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[[Page 49620]]

[GRAPHIC] [TIFF OMITTED] TP03SE21.026

    With the SCC discounted at 2.5% and other benefits and costs 
discounted at 3%, NHTSA estimates that costs and benefits could be 
approximately $120 billion and $121 billion, respectively, such that 
the present value of aggregate net benefits to society could be 
somewhat less than $1 billion. With the social cost of carbon (SCC) 
discounted at 3% and other benefits and costs discounted at 7%, NHTSA 
estimates approximately $90 billion in costs and $76 billion in 
benefits could be attributable to vehicles produced prior to MY 2030 
over the course of their lives, such that the present value of 
aggregate net costs to society could be approximately $15 billion.\13\
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    \12\ Assumes no rebound effect.
    \13\ NHTSA interprets the 2021 IWG draft guidance as indicating 
that a 2.5% discount rate for the SCC is consistent with discounting 
near-term benefits and costs of the proposal at the OMB-recommended 
consumption discount rate of 3%. For the OMB-recommended discount 
rate of 7%, NHTSA concluded that a 3% discount rate for the SCC was 
reasonable given that the IWG draft guidance suggested that the 
appropriate discount rate for the SCC was likely lower than 3%. 
NHTSA refers readers specifically to pp. 16-17 of that guidance, 
available at <a href="https://www.whitehouse.gov/wp-content/uploads/2021/02/TechnicalSupportDocument_SocialCostofCarbonMethaneNitrousOxide.pdf?source=email">https://www.whitehouse.gov/wp-content/uploads/2021/02/TechnicalSupportDocument_SocialCostofCarbonMethaneNitrousOxide.pdf?source=email</a>.
[GRAPHIC] [TIFF OMITTED] TP03SE21.027

    Model results can be viewed many different ways, and NHTSA's 
rulemaking considers both ``model year'' and ``calendar year'' 
perspectives. The ``model year'' perspective, above, considers vehicles 
projected to be produced in some range of model years, and accounts for 
impacts, benefits, and costs attributable to these vehicles from the 
present (from the model year's perspective, 2020) until they are 
projected to be scrapped. The bulk of NHTSA's analysis considers 
vehicles produced prior to model year 2030, accounting for the 
estimated indirect impacts new standards could have on the remaining 
operation of vehicles already in service. This perspective emphasizes 
impacts on those model years nearest to those (2024-2026) for which 
NHTSA is proposing new standards. NHTSA's analysis also presents some 
results focused only on model years 2024-2026, setting aside the 
estimated indirect impacts on earlier model years, and the impacts 
estimated to occur during model years 2027-2029, as some manufacturers 
and products ``catch up'' to the standards.
    Another way to present the benefits and costs of the proposal is 
the ``calendar year'' perspective shown in Table II-10, which is 
similar to how EPA presents benefits and costs in its proposal for GHG 
standards for MYs 2023-2026. The calendar year perspective considers 
all vehicles projected to be in service in each of some range of future 
calendar years. NHTSA's presentation of results from this perspective 
considers calendar years 2020-2050, because the model's representation 
of the full on-road fleet extends through 2050. Unlike the model year 
perspective, this perspective includes vehicles projected produced 
during model years 2030-2050. This perspective emphasizes longer-term 
impacts that could accrue if standards were to continue without change. 
Table II-10 shows costs and benefits for MYs 2023-2026 while Table II-9 
shows costs and benefits through MY 2029.

[[Page 49621]]

[GRAPHIC] [TIFF OMITTED] TP03SE21.028

    Though based on the exact same model results, these two 
perspectives provide considerably different views of estimated costs 
and benefits. Because technology costs account for a large share of 
overall estimated costs, and are also projected to decline over time 
(as manufacturers gain more experience with new technologies), costs 
tend to be ``front loaded''--occurring early in a vehicle's life and 
tending to be higher in earlier model years than in later model years. 
Conversely, because social benefits of standards occur as vehicles are 
driven, and because both fuel prices and the social cost of 
CO<INF>2</INF> emissions are projected to increase in the future, 
benefits tend to be ``back loaded.'' As a result, estimates of future 
fuel savings, CO<INF>2</INF> reductions, and net social benefits are 
higher under the calendar year perspective than under the model year 
perspective. On the other hand, with longer-term impacts playing a 
greater role, the calendar year perspective is more subject to 
uncertainties regarding, for example, future technology costs and fuel 
prices.
    Even though NHTSA and EPA estimate benefits, costs, and net 
benefits using similar methodologies and achieve similar results, 
different approaches to accounting may give the false appearance of 
significant divergences. Table II-10 above presents NHTSA's results 
using comparable accounting to EPA's preamble Table 5. EPA also 
presents cost and benefit information in its RIA over calendar years 
2021 through 2050. The numbers most comparable to those presented in 
EPA's RIA are those NHTSA developed to complete its Supplemental 
Environmental Impact Statement (SEIS) using an identical accounting 
approach. This is because the statutory limitations constraining 
NHTSA's standard setting analysis, such as those in 49 U.S.C. 32902(h) 
prohibiting consideration of full vehicle electrification during the 
rulemaking timeframe, or consideration of the trading or transferring 
of overcompliance credits, do not similarly apply to its EIS 
analysis.\14\ NHTSA's EIS analysis estimates $312 billion in costs, 
$443 billion in benefits, and $132 billion in net benefits using a 3% 
discount rate over calendar years 2021 through 2050.\15\ NHTSA 
describes its cost and benefit accounting approach in Section V of this 
preamble.
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    \14\ As the EIS analysis contains information that NHTSA is 
statutorily prevented from considering, the agency does not rely on 
this analysis in regulatory decision-making.
    \15\ See PRIA Chapter 6.5 for more information regarding NHTSA's 
estimates of annual benefits and costs using NHTSA's standard 
setting analysis. See Tables B-7-25 through B-7-30 in Appendix II of 
the PRIA for a more detailed breakdown of NHTSA's EIS analysis.
---------------------------------------------------------------------------

C. Why does NHTSA tentatively believe the proposal would be maximum 
feasible, and how and why is this tentative conclusion different from 
the 2020 final rule?

    NHTSA's tentative conclusion, after consideration of the factors 
described below and information in the administrative record for this 
action, is that 8 percent increases in stringency for MYs 2024-2026 
(Alternative 2 of this analysis) are maximum feasible. The Department 
of Transportation is deeply committed to working aggressively to 
improve energy conservation and reduce security risks associated with 
energy use, and higher standards appear increasingly likely to be 
economically practicable given almost-daily announcements by major 
automakers about forthcoming new high-fuel-economy vehicle models, as 
described in more detail below. Despite only one year having passed 
since the 2020 final rule, enough has changed in the U.S. and the world 
that revisiting the CAFE standards for MYs 2024-2026, and raising their 
stringency considerably, is both appropriate and reasonable.
    The 2020 final rule set CAFE standards that increased at 1.5 
percent per year for cars and trucks for MYs 2021-2026, in large part 
because it prioritized industry concerns and reducing vehicle purchase 
costs to consumers and manufacturers. This proposed rule acknowledges 
the priority of energy conservation, consistent with NHTSA's statutory 
authority. Moreover, NHTSA is also legally required to consider the 
environmental implications of this action under NEPA, and while the 
2020 final rule did undertake a NEPA analysis, it did not prioritize 
the environmental considerations aspects of the statutory need of the 
U.S. to conserve energy.
    NHTSA recognizes that the amount of lead time available before MY 
2024 is less than what was provided in the 2012 rule. As will be 
discussed further in Section VI, NHTSA believes that the evidence 
suggests that the proposed standards are still economically 
practicable.
    We note further that while this proposal is different from the 2020 
final rule (and also from the 2012 final rule), NHTSA, like any other 
Federal agency, is afforded an opportunity to reconsider prior views 
and, when warranted, to adopt new positions. Indeed, as a matter of 
good governance, agencies should revisit their positions when 
appropriate, especially to ensure that their actions and regulations 
reflect legally sound interpretations of the agency's authority and 
remain consistent with the agency's views and practices. As a matter of 
law, ``an Agency is entitled to change its interpretation of a 
statute.'' \16\ Nonetheless, ``[w]hen an Agency adopts a materially 
changed interpretation of a statute, it must in addition provide a 
`reasoned analysis' supporting its decision to revise its 
interpretation.'' \17\

[[Page 49622]]

This preamble and the accompanying TSD and PRIA all provide extensive 
detail on the agency's updated analysis, and Section VI contains the 
agency's explanation of how the agency has considered that analysis and 
other relevant information in tentatively determining that the proposed 
CAFE standards are maximum feasible for MYs 2024-2026 passenger cars 
and light trucks.
---------------------------------------------------------------------------

    \16\ Phoenix Hydro Corp. v. FERC, 775 F.2d 1187, 1191 (D.C. Cir. 
1985).
    \17\ Alabama Educ. Ass'n v. Chao, 455 F.3d 386, 392 (D.C. Cir. 
2006) (quoting Motor Vehicle Mfrs. Ass'n of U.S., Inc. v. State Farm 
Mut. Auto. Ins. Co., 463 U.S. 29, 57 (1983)); see also Encino 
Motorcars, LLC v. Navarro, 136 S.Ct. 2117, 2125 (2016) (``Agencies 
are free to change their existing policies as long as they provide a 
reasoned explanation for the change.'') (citations omitted).
---------------------------------------------------------------------------

D. How is this proposal consistent with EPA's proposal and with 
California's programs?

    The NHTSA and EPA proposals remain coordinated despite being issued 
as separate regulatory actions. Because NHTSA and EPA are regulating 
the exact same vehicles and manufacturer will use the same technologies 
to meet both sets of standards, NHTSA and EPA coordinated during the 
development of each agency's independent proposal to revise the 
standards set forth in the 2020 final rule. The NHTSA-proposed CAFE and 
EPA-proposed CO<INF>2</INF> standards for MY 2026 represent roughly 
equivalent levels of stringency and may serve as a coordinated starting 
point for subsequent standards. While the proposed CAFE and 
CO<INF>2</INF> standards for MYs 2024-2025 are different, this is 
largely due to the difference in the ``start year'' for the revised 
regulations--EPA is proposing to revise standards for MY 2023, while 
EPCA's lead time requirements, which do not apply to EPA, prevent NHTSA 
from proposing revised standards until MY 2024. In order to set 
standards for MY 2023, EPA intends to issue its final rule by December 
31, 2021, whereas NHTSA has until April 2022 to finalize standards for 
MY 2024. The difference in timing makes separate rulemaking actions 
reasonable and prudent. The specific differences in what the two 
agencies' standards require become smaller each year, until alignment 
is achieved. The agencies still have coordinated closely to minimize 
inconsistency between the programs and will continue to do so through 
the final rule stage.
    While NHTSA's and EPA's programs differ in certain other respects, 
like programmatic flexibilities, those differences are not new in this 
proposal. Some parts of the programs are harmonized, and others differ, 
often as a result of statute. Since NHTSA and EPA began regulating 
together under President Obama, differences in programmatic 
flexibilities have meant that manufacturers have had (and will have) to 
plan their compliance strategies considering both the CAFE standards 
and the GHG standards and assure that they are in compliance with both, 
while still building a single fleet of vehicles to accomplish that 
goal. NHTSA is proposing CAFE standards that increase at 8 percent per 
year over MYs 2024-2026 because that is what NHTSA has tentatively 
concluded is maximum feasible in those model years, under the EPCA 
factors, and is confident that industry would still be able to build a 
single fleet of vehicles to meet both the NHTSA and EPA standards. Auto 
manufacturers are extremely sophisticated companies, well-able to 
manage complex compliance strategies that account for multiple 
regulatory programs concurrently. If different agencies' standards are 
more binding for some companies in certain years, this does not mean 
that manufacturers must build multiple fleets of vehicles, simply that 
they will have to be more strategic about how they build their fleet.
    NHTSA has also considered and accounted for California's ZEV 
mandate (and its adoption by a number of other states) in developing 
the baseline for this proposal, and has also accounted for the 
Framework Agreements between California, BMW, Ford, Honda, VWA, and 
Volvo. NHTSA believes that it is reasonable to include ZEV in the 
baseline for this proposal regardless of whether California receives a 
waiver of preemption under the Clean Air Act (CAA) because, according 
to California, industry overcompliance with the ZEV mandate has been 
extensive, which indicates that whether or not a waiver exists, many 
companies intend to produce ZEVs in volumes comparable to what a ZEV 
mandate would require. Because no decision has yet been made on a CAA 
waiver for California, and because modeling a sub-national fleet is not 
currently an analytical option for NHTSA, NHTSA has not expressly 
accounted for California GHG standards in the analysis for this 
proposal, although we seek comment on whether and how to account for 
them in the final rule. Chapter 6 of the accompanying PRIA shows the 
estimated effects of all of these programs simultaneously.

III. Technical Foundation for NPRM Analysis

A. Why does NHTSA conduct this analysis?

    NHTSA is proposing to establish revised CAFE standards for 
passenger cars and light trucks produced for model years (MYs) 2024-
2026. NHTSA's review of the existing standards is consistent with 
Executive Order 13990, Protecting Public Health and the Environment and 
Restoring Science to Tackle the Climate Crisis, signed on January 20, 
2021, directing the review of the 2020 final rule that established CAFE 
standards for MYs 2021-2026 and the consideration of whether to 
suspend, revise, or rescind that action by July 2021.\18\ NHTSA 
establishes CAFE standards under the Energy Policy and Conservation 
Act, as amended, and this proposal is undertaken pursuant to that 
authority. This proposal would require CAFE stringency for both 
passenger cars and light trucks to increase at a rate of 8 percent per 
year annually from MY 2024 through MY 2026. NHTSA estimates that over 
the useful lives of vehicles produced prior to MY 2030, the proposal 
would save about 50 billion gallons of gasoline and increase 
electricity consumption by about 275 TWh. Accounting for emissions from 
both vehicles and upstream energy sector processes (e.g., petroleum 
refining and electricity generation), NHTSA estimates that the proposal 
would reduce greenhouse gas emissions by about 465 million metric tons 
of carbon dioxide (CO<INF>2</INF>), about 500 thousand tons metric tons 
of methane (CH<INF>4</INF>), and about 12 thousand tons of nitrous 
oxide (N<INF>2</INF>O).
---------------------------------------------------------------------------

    \18\ 86 FR 7037 (Jan. 25, 2021).
---------------------------------------------------------------------------

    When NHTSA promulgates new regulations, it generally presents an 
analysis that estimates the impacts of such regulations, and the 
impacts of other regulatory alternatives. These analyses derive from 
statutes such as the Administrative Procedure Act (APA) and National 
Environmental Policy Act (NEPA), from Executive orders (such as 
Executive Order 12866 and 13653), and from other administrative 
guidance (e.g., Office of Management Budget Circular A-4). For CAFE, 
the Energy Policy and Conservation Act (EPCA), as amended by the Energy 
Independence and Security Act (EISA), contains a variety of provisions 
that require NHTSA to consider certain compliance elements in certain 
ways and avoid considering other things, in determining maximum 
feasible CAFE standards. Collectively, capturing all of these 
requirements and guidance elements analytically means that, at least 
for CAFE, NHTSA presents an analysis that spans a meaningful range of 
regulatory alternatives, that quantifies a range of technological, 
economic, and environmental impacts, and that does so in a manner that 
accounts for EPCA's express requirements for the CAFE program

[[Page 49623]]

(e.g., passenger cars and light trucks are regulated separately, and 
the standard for each fleet must be set at the maximum feasible level 
in each model year).
    NHTSA's decision regarding the proposed standards is thus supported 
by extensive analysis of potential impacts of the regulatory 
alternatives under consideration. Along with this preamble, a Technical 
Support Document (TSD), a Preliminary Regulatory Impact Analysis 
(PRIA), and a Supplemental Environmental Impact Statement (SEIS), 
together provide an extensive and detailed enumeration of related 
methods, estimates, assumptions, and results. NHTSA's analysis has been 
constructed specifically to reflect various aspects of governing law 
applicable to CAFE standards and has been expanded and improved in 
response to comments received to the prior rulemaking and based on 
additional work conducted over the last year. Further improvements may 
be made based on comments received to this proposal, the 2021 NAS 
Report,\19\ and other additional work generally previewed in these 
rulemaking documents. The analysis for this proposal aided NHTSA in 
implementing its statutory obligations, including the weighing of 
various considerations, by reasonably informing decision-makers about 
the estimated effects of choosing different regulatory alternatives.
---------------------------------------------------------------------------

    \19\ National Academies of Sciences, Engineering, and Medicine 
(NASEM), 2021. Assessment of Technologies for Improving Fuel Economy 
of Light-Duty Vehicles--2025-2035, Washington, DC: The National 
Academies Press (hereafter, ``2021 NAS Report''). Available at 
<a href="https://www.nationalacademies.org/our-work/assessment-of-technologies-for-improving-fuel-economy-of-light-duty-vehicles-phase-3">https://www.nationalacademies.org/our-work/assessment-of-technologies-for-improving-fuel-economy-of-light-duty-vehicles-phase-3</a> and for hard-copy review at DOT headquarters.
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    NHTSA's analysis makes use of a range of data (i.e., observations 
of things that have occurred), estimates (i.e., things that may occur 
in the future), and models (i.e., methods for making estimates). Two 
examples of data include (1) records of actual odometer readings used 
to estimate annual mileage accumulation at different vehicle ages and 
(2) CAFE compliance data used as the foundation for the ``analysis 
fleet'' containing, among other things, production volumes and fuel 
economy levels of specific configurations of specific vehicle models 
produced for sale in the U.S. Two examples of estimates include (1) 
forecasts of future GDP growth used, with other estimates, to forecast 
future vehicle sales volumes and (2) the ``retail price equivalent'' 
(RPE) factor used to estimate the ultimate cost to consumers of a given 
fuel-saving technology, given accompanying estimates of the 
technology's ``direct cost,'' as adjusted to account for estimated 
``cost learning effects'' (i.e., the tendency that it will cost a 
manufacturer less to apply a technology as the manufacturer gains more 
experience doing so).
    NHTSA uses the CAFE Compliance and Effects Modeling System (usually 
shortened to the ``CAFE Model'') to estimate manufacturers' potential 
responses to new CAFE and CO<INF>2</INF> standards and to estimate 
various impacts of those responses. DOT's Volpe National Transportation 
Systems Center (often simply referred to as the ``Volpe Center'') 
develops, maintains, and applies the model for NHTSA. NHTSA has used 
the CAFE Model to perform analyses supporting every CAFE rulemaking 
since 2001. The 2016 rulemaking regarding heavy-duty pickup and van 
fuel consumption and CO<INF>2</INF> emissions also used the CAFE Model 
for analysis (81 FR 73478, October 25, 2016).
    The basic design of the CAFE Model is as follows: the system first 
estimates how vehicle manufacturers might respond to a given regulatory 
scenario, and from that potential compliance solution, the system 
estimates what impact that response will have on fuel consumption, 
emissions, and economic externalities. In a highly-summarized form, 
Figure III-1 shows the basic categories of CAFE Model procedures and 
the sequential flow between different stages of the modeling. The 
diagram does not present specific model inputs or outputs, as well as 
many specific procedures and model interactions. The model 
documentation accompanying this preamble presents these details, and 
Chapter 1 of the TSD contains a more detailed version of this flow 
diagram for readers who are interested.
BILLING CODE 4910-59-P

[[Page 49624]]

[GRAPHIC] [TIFF OMITTED] TP03SE21.029

BILLING CODE 4910-59-C
    More specifically, the model may be characterized as an integrated 
system of models. For example, one model estimates manufacturers' 
responses, another estimates resultant changes in total vehicle sales, 
and still another estimates resultant changes in fleet turnover (i.e., 
scrappage). Additionally, and importantly, the model does not determine 
the form or stringency of the standards. Instead, the model applies 
inputs specifying the form and stringency of standards to be analyzed 
and produces outputs showing the impacts of manufacturers working to 
meet those standards, which become the basis for comparing between 
different potential stringencies. A regulatory scenario, meanwhile, 
involves specification of the form, or shape, of the standards (e.g., 
flat standards, or linear or logistic attribute-based standards), scope 
of passenger car and truck regulatory classes, and stringency of the 
CAFE standards for each model year to be analyzed. For example, a 
regulatory scenario may define CAFE standards that increase in 
stringency by 8 percent per year for 3 consecutive years.
    Manufacturer compliance simulation and the ensuing effects 
estimation, collectively referred to as compliance modeling, encompass 
numerous subsidiary elements. Compliance simulation begins with a 
detailed user-provided \20\ initial forecast of the vehicle models 
offered for sale during the simulation period. The compliance 
simulation then attempts to bring each manufacturer into compliance 
with the standards \21\ defined by the regulatory scenario contained 
within an input file developed by the user.
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    \20\ Because the CAFE Model is publicly available, anyone can 
develop their own initial forecast (or other inputs) for the model 
to use. The DOT-developed market data file that contains the 
forecast used for this proposal is available on NHTSA's website.
    \21\ With appropriate inputs, the model can also be used to 
estimate impacts of manufacturers' potential responses to new 
CO<INF>2</INF> standards and to California's ZEV program.
---------------------------------------------------------------------------

    Estimating impacts involves calculating resultant changes in new 
vehicle costs, estimating a variety of costs (e.g., for fuel) and 
effects (e.g., CO<INF>2</INF> emissions from fuel combustion) occurring 
as vehicles are driven over their lifetimes before eventually being

[[Page 49625]]

scrapped, and estimating the monetary value of these effects. 
Estimating impacts also involves consideration of consumer responses--
e.g., the impact of vehicle fuel economy, operating costs, and vehicle 
price on consumer demand for passenger cars and light trucks. Both 
basic analytical elements involve the application of many analytical 
inputs. Many of these inputs are developed outside of the model and not 
by the model. For example, the model applies fuel prices; it does not 
estimate fuel prices.
    NHTSA also uses EPA's MOVES model to estimate ``tailpipe'' (a.k.a. 
``vehicle'' or ``downstream'') emission factors for criteria 
pollutants,\22\ and uses four Department of Energy (DOE) and DOE-
sponsored models to develop inputs to the CAFE Model, including three 
developed and maintained by DOE's Argonne National Laboratory. The 
agency uses the DOE Energy Information Administration's (EIA's) 
National Energy Modeling System (NEMS) to estimate fuel prices,\23\ and 
uses Argonne's Greenhouse gases, Regulated Emissions, and Energy use in 
Transportation (GREET) model to estimate emissions rates from fuel 
production and distribution processes.\24\ DOT also sponsored DOE/
Argonne to use Argonne's Autonomie full-vehicle modeling and simulation 
system to estimate the fuel economy impacts for roughly a million 
combinations of technologies and vehicle types.<SUP>25 26</SUP> The TSD 
and PRIA describe details of the agency's use of these models. In 
addition, as discussed in the SEIS accompanying this NPRM, DOT relied 
on a range of climate models to estimate impacts on climate, air 
quality, and public health. The SEIS discusses and describes the use of 
these models.
---------------------------------------------------------------------------

    \22\ See <a href="https://www.epa.gov/moves">https://www.epa.gov/moves</a>. This proposal uses version 
MOVES3, available at <a href="https://www.epa.gov/moves/latest-version-motor-vehicle-emission-simulator-moves">https://www.epa.gov/moves/latest-version-motor-vehicle-emission-simulator-moves</a>.
    \23\ See <a href="https://www.eia.gov/outlooks/aeo/info_nems_archive.php">https://www.eia.gov/outlooks/aeo/info_nems_archive.php</a>. 
This proposal uses fuel prices estimated using the Annual Energy 
Outlook (AEO) 2021 version of NEMS (see <a href="https://www.eia.gov/outlooks/aeo/pdf/02%20AEO2021%20Petroleum.pdf">https://www.eia.gov/outlooks/aeo/pdf/02%20AEO2021%20Petroleum.pdf</a>).
    \24\ Information regarding GREET is available at <a href="https://greet.es.anl.gov/index.php">https://greet.es.anl.gov/index.php</a>. This NPRM uses the 2020 version of 
GREET.
    \25\ As part of the Argonne simulation effort, individual 
technology combinations simulated in Autonomie were paired with 
Argonne's BatPaC model to estimate the battery cost associated with 
each technology combination based on characteristics of the 
simulated vehicle and its level of electrification. Information 
regarding Argonne's BatPaC model is available at <a href="https://www.anl.gov/cse/batpac-model-software">https://www.anl.gov/cse/batpac-model-software</a>.
    \26\ In addition, the impact of engine technologies on fuel 
consumption, torque, and other metrics was characterized using GT-
POWER simulation modeling in combination with other engine modeling 
that was conducted by IAV Automotive Engineering, Inc. (IAV). The 
engine characterization ``maps'' resulting from this analysis were 
used as inputs for the Autonomie full-vehicle simulation modeling. 
Information regarding GT-POWER is available at <a href="https://www.gtisoft.com/gt-suite-applications/propulsion-systems/gt-power-engine-simulation-software">https://www.gtisoft.com/gt-suite-applications/propulsion-systems/gt-power-engine-simulation-software</a>.
---------------------------------------------------------------------------

    To prepare for analysis supporting this proposal, DOT has refined 
and expanded the CAFE Model through ongoing development. Examples of 
such changes, some informed by past external comments, made since early 
2020 include:
    <bullet> Inclusion of 400- and 500-mile BEVs;
    <bullet> Inclusion of high compression ratio (HCR) engines with 
cylinder deactivation;
    <bullet> Accounting for manufacturers' responses to both CAFE and 
CO<INF>2</INF> standards jointly (rather than only separately)
    <bullet> Accounting for the ZEV mandates applicable in California 
and the ``Section 177'' states;
    <bullet> Accounting for some vehicle manufacturers' (BMW, Ford, 
Honda, VW, and Volvo) voluntary agreement with the State of California 
to continued annual national-level reductions of vehicle greenhouse gas 
emissions through MY 2026, with greater rates of electrification than 
would have been required under the 2020 Federal final rule; \27\
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    \27\ For more information on the Framework Agreements for Clean 
Cars, including the specific agreements signed by individual 
manufacturers, see <a href="https://ww2.arb.ca.gov/news/framework-agreements-clean-cars">https://ww2.arb.ca.gov/news/framework-agreements-clean-cars</a>.
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    [cir] Inclusion of CAFE civil penalties in the ``effective cost'' 
metric used when simulating manufacturers' potential application of 
fuel-saving technologies;
    [cir] Refined procedures to estimate health effects and 
corresponding monetized damages attributable to criteria pollutant 
emissions;
    [cir] New procedures to estimate the impacts and corresponding 
monetized damages of highway vehicle crashes that do not result in 
fatalities;
    [cir] Procedures to ensure that modeled technology application and 
production volumes are the same across all regulatory alternatives in 
the earliest model years; and
    [cir] Procedures to more precisely focus application of EPCA's 
``standard setting constraints'' (i.e., regarding the consideration of 
compliance credits and additional dedicated alternative fueled 
vehicles) to only those model years for which NHTSA is proposing or 
finalizing new standards.
    These changes reflect DOT's long-standing commitment to ongoing 
refinement of its approach to estimating the potential impacts of new 
CAFE standards.
    NHTSA underscores that this analysis exercises the CAFE Model in a 
manner that explicitly accounts for the fact that in producing a single 
fleet of vehicles for sale in the United States, manufacturers face the 
combination of CAFE standards, EPA CO<INF>2</INF> standards, and ZEV 
mandates, and for five manufacturers, the voluntary agreement with 
California to more stringent CO<INF>2</INF> reduction requirements 
(also applicable to these manufacturers' total production for the U.S. 
market) through model year 2026. These regulations and contracts have 
important structural and other differences that affect the strategy a 
manufacturer could use to comply with each of the above.
    As explained, the analysis is designed to reflect a number of 
statutory and regulatory requirements applicable to CAFE and tailpipe 
CO<INF>2</INF> standard-setting. EPCA contains a number of requirements 
governing the scope and nature of CAFE standard setting. Among these, 
some have been in place since EPCA was first signed into law in 1975, 
and some were added in 2007, when Congress passed EISA and amended 
EPCA. EPCA/EISA requirements regarding the technical characteristics of 
CAFE standards and the analysis thereof include, but are not limited 
to, the following, and the analysis reflects these requirements as 
summarized:
    Corporate Average Standards: The provision at 49 U.S.C. 32902 
requires standards that apply to the average fuel economy levels 
achieved by each corporation's fleets of vehicles produced for sale in 
the U.S.\28\ The CAFE Model calculates the CAFE and CO<INF>2</INF> 
levels of each manufacturer's fleets based on estimated production 
volumes and characteristics, including fuel economy levels, of distinct 
vehicle models that could be produced for sale in the U.S.
---------------------------------------------------------------------------

    \28\ This differs from safety standards and traditional 
emissions standards, which apply separately to each vehicle. For 
example, every vehicle produced for sale in the U.S. must, on its 
own, meet all applicable Federal motor vehicle safety standards 
(FMVSS), but no vehicle produced for sale must, on its own, meet 
Federal fuel economy standards. Rather, each manufacturer is 
required to produce a mix of vehicles that, taken together, achieve 
an average fuel economy level no less than the applicable minimum 
level.
---------------------------------------------------------------------------

    Separate Standards for Passenger Cars and Light Trucks: The 
provision at 49 U.S.C. 32902 requires the Secretary of Transportation 
to set CAFE standards separately for passenger cars and light trucks. 
The CAFE Model accounts separately for passenger cars and light trucks 
when it analyzes CAFE or CO<INF>2</INF> standards, including 
differentiated standards and compliance.

[[Page 49626]]

    Attribute-Based Standards: The provision at 49 U.S.C. 32902 
requires the Secretary of Transportation to define CAFE standards as 
mathematical functions expressed in terms of one or more vehicle 
attributes related to fuel economy. This means that for a given 
manufacturer's fleet of vehicles produced for sale in the U.S. in a 
given regulatory class and model year, the applicable minimum CAFE 
requirement (i.e., the numerical value of the requirement) is computed 
based on the applicable mathematical function, and the mix and 
attributes of vehicles in the manufacturer's fleet. The CAFE Model 
accounts for such functions and vehicle attributes explicitly.
    Separately Defined Standards for Each Model Year: The provision at 
49 U.S.C. 32902 requires the Secretary to set CAFE standards 
(separately for passenger cars and light trucks \29\) at the maximum 
feasible levels in each model year. The CAFE Model represents each 
model year explicitly, and accounts for the production relationships 
between model years.\30\
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    \29\ 49 U.S.C. chapter 329 uses the term ``non-passenger 
automobiles,'' while NHTSA uses the term ``light trucks'' in its 
CAFE regulations. The terms' meanings are identical.
    \30\ For example, a new engine first applied to given vehicle 
model/configuration in model year 2020 will most likely be ``carried 
forward'' to model year 2021 of that same vehicle model/
configuration, in order to reflect the fact that manufacturers do 
not apply brand-new engines to a given vehicle model every single 
year. The CAFE Model is designed to account for these real-world 
factors.
---------------------------------------------------------------------------

    Separate Compliance for Domestic and Imported Passenger Car Fleets: 
The provision at 49 U.S.C. 32904 requires the EPA Administrator to 
determine CAFE compliance separately for each manufacturers' fleets of 
domestic passenger cars and imported passenger cars, which 
manufacturers must consider as they decide how to improve the fuel 
economy of their passenger car fleets. The CAFE Model accounts 
explicitly for this requirement when simulating manufacturers' 
potential responses to CAFE standards, and combines any given 
manufacturer's domestic and imported cars into a single fleet when 
simulating that manufacturer's potential response to CO<INF>2</INF> 
standards (because EPA does not have separate standards for domestic 
and imported passenger cars).
    Minimum CAFE Standards for Domestic Passenger Car Fleets: The 
provision at 49 U.S.C. 32902 requires that domestic passenger car 
fleets meet a minimum standard, which is calculated as 92 percent of 
the industry-wide average level required under the applicable 
attribute-based CAFE standard, as projected by the Secretary at the 
time the standard is promulgated. The CAFE Model accounts explicitly 
for this requirement for CAFE standards and sets this requirement aside 
for CO<INF>2</INF> standards.
    Civil Penalties for Noncompliance: The provision at 49 U.S.C. 32912 
(and implementing regulations) prescribes a rate (in dollars per tenth 
of a mpg) at which the Secretary is to levy civil penalties if a 
manufacturer fails to comply with a CAFE standard for a given fleet in 
a given model year, after considering available credits. Some 
manufacturers have historically demonstrated a willingness to pay civil 
penalties rather than achieving full numerical compliance across all 
fleets. The CAFE Model calculates civil penalties for CAFE shortfalls 
and provides means to estimate that a manufacturer might stop adding 
fuel-saving technologies once continuing to do so would be effectively 
more ``expensive'' (after accounting for fuel prices and buyers' 
willingness to pay for fuel economy) than paying civil penalties. The 
CAFE Model does not allow civil penalty payment as an option for 
CO<INF>2</INF> standards.
    Dual-Fueled and Dedicated Alternative Fuel Vehicles: For purposes 
of calculating CAFE levels used to determine compliance, 49 U.S.C. 
32905 and 32906 specify methods for calculating the fuel economy levels 
of vehicles operating on alternative fuels to gasoline or diesel 
through MY 2020. After MY 2020, methods for calculating alternative 
fuel vehicle (AFV) fuel economy are governed by regulation. The CAFE 
Model is able to account for these requirements explicitly for each 
vehicle model. However, 49 U.S.C. 32902 prohibits consideration of the 
fuel economy of dedicated alternative fuel vehicle (AFV) models when 
NHTSA determines what levels of CAFE standards are maximum feasible. 
The CAFE Model therefore has an option to be run in a manner that 
excludes the additional application of dedicated AFV technologies in 
model years for which maximum feasible standards are under 
consideration. As allowed under NEPA for analysis appearing in EISs 
informing decisions regarding CAFE standards, the CAFE Model can also 
be run without this analytical constraint. The CAFE Model does account 
for dual- and alternative fuel vehicles when simulating manufacturers' 
potential responses to CO<INF>2</INF> standards. For natural gas 
vehicles, both dedicated and dual-fueled, EPA has a multiplier of 2.0 
for model years 2022-2026.\31\
---------------------------------------------------------------------------

    \31\ While EPA is proposing changes to this and other 
flexibility provisions in its separate NPRM, for purposes of this 
NPRM, the CAFE Model only reflects the current EPA regulatory 
flexibilities.
---------------------------------------------------------------------------

    ZEV Mandates: The CAFE Model can simulate manufacturers' compliance 
with ZEV mandates applicable in California and ``Section 177'' \32\ 
states. The approach involves identifying specific vehicle model/
configurations that could be replaced with PHEVs or BEVs, and 
immediately making these changes in each model year, before beginning 
to consider the potential that other technologies could be applied 
toward compliance with CAFE or CO<INF>2</INF> standards.
---------------------------------------------------------------------------

    \32\ The term ``Section 177'' states refers to states which have 
elected to adopt California's standards in lieu of Federal 
requirements, as allowed under Section 177 of the CAA.
---------------------------------------------------------------------------

    Creation and Use of Compliance Credits: The provision at 49 U.S.C. 
32903 provides that manufacturers may earn CAFE ``credits'' by 
achieving a CAFE level beyond that required of a given fleet in a given 
model year, and specifies how these credits may be used to offset the 
amount by which a different fleet falls short of its corresponding 
requirement. These provisions allow credits to be ``carried forward'' 
and ``carried back'' between model years, transferred between regulated 
classes (domestic passenger cars, imported passenger cars, and light 
trucks), and traded between manufacturers. However, credit use is also 
subject to specific statutory limits. For example, CAFE compliance 
credits can be carried forward a maximum of five model years and 
carried back a maximum of three model years. Also, EPCA/EISA caps the 
amount of credit that can be transferred between passenger car and 
light truck fleets and prohibits manufacturers from applying traded or 
transferred credits to offset a failure to achieve the applicable 
minimum standard for domestic passenger cars. The CAFE Model explicitly 
simulates manufacturers' potential use of credits carried forward from 
prior model years or transferred from other fleets.\33\ The provision 
at 49

[[Page 49627]]

U.S.C. 32902 prohibits consideration of manufacturers' potential 
application of CAFE compliance credits when setting maximum feasible 
CAFE standards. The CAFE Model can be operated in a manner that 
excludes the application of CAFE credits for a given model year under 
consideration for standard setting. For modeling CO<INF>2</INF> 
standards, the CAFE Model does not limit transfers. Insofar as the CAFE 
Model can be exercised in a manner that simulates trading of 
CO<INF>2</INF> compliance credits, such simulations treat trading as 
unlimited.\34\
---------------------------------------------------------------------------

    \33\ The CAFE Model does not explicitly simulate the potential 
that manufacturers would carry CAFE or CO<INF>2</INF> credits back 
(i.e., borrow) from future model years, or acquire and use CAFE 
compliance credits from other manufacturers. At the same time, 
because EPA has currently elected not to limit credit trading, the 
CAFE Model can be exercised in a manner that simulates unlimited 
(a.k.a. ``perfect'') CO<INF>2</INF> compliance credit trading 
throughout the industry (or, potentially, within discrete trading 
``blocs''). NHTSA believes there is significant uncertainty in how 
manufacturers may choose to employ these particular flexibilities in 
the future: For example, while it is reasonably foreseeable that a 
manufacturer who over-complies in one year may ``coast'' through 
several subsequent years relying on those credits rather than 
continuing to make technology improvements, it is harder to assume 
with confidence that manufacturers will rely on future technology 
investments to offset prior-year shortfalls, or whether/how 
manufacturers will trade credits with market competitors rather than 
making their own technology investments. Historically, carry-back 
and trading have been much less utilized than carry-forward, for a 
variety of reasons including higher risk and preference not to `pay 
competitors to make fuel economy improvements we should be making' 
(to paraphrase one manufacturer), although NHTSA recognizes that 
carry-back and trading are used more frequently when standards 
increase in stringency more rapidly. Given the uncertainty just 
discussed, and given also the fact that the agency has yet to 
resolve some of the analytical challenges associated with simulating 
use of these flexibilities, the agency considers borrowing and 
trading to involve sufficient risk that it is prudent to support 
this proposal with analysis that sets aside the potential that 
manufacturers could come to depend widely on borrowing and trading. 
While compliance costs in real life may be somewhat different from 
what is modeled today as a result of this analytical decision, that 
is broadly true no matter what, and the agency does not believe that 
the difference would be so great that it would change the policy 
outcome. Furthermore, a manufacturer employing a trading strategy 
would presumably do so because it represents a lower-cost compliance 
option. Thus, the estimates derived from this modeling approach are 
likely to be conservative in this respect, with real-world 
compliance costs possibly being lower.
    \34\ To avoid making judgments about possible future trading 
activity, the model simulates trading by combining all manufacturers 
into a single entity, so that the most cost-effective choices are 
made for the fleet as a whole.
---------------------------------------------------------------------------

    Statutory Basis for Stringency: The provision at 49 U.S.C. 32902 
requires the Secretary to set CAFE standards at the maximum feasible 
levels, considering technological feasibility, economic practicability, 
the need of the United States to conserve energy, and the impact of 
other motor vehicle standards of the Government. EPCA/EISA authorizes 
the Secretary to interpret these factors, and as the Department's 
interpretation has evolved, NHTSA has continued to expand and refine 
its qualitative and quantitative analysis to account for these 
statutory factors. For example, one of the ways that economic 
practicability considerations are incorporated into the analysis is 
through the technology effectiveness determinations: The Autonomie 
simulations reflect the agency's judgment that it would not be 
economically practicable for a manufacturer to ``split'' an engine 
shared among many vehicle model/configurations into myriad versions 
each optimized to a single vehicle model/configuration.
    National Environmental Policy Act: In addition, NEPA requires the 
Secretary to issue an EIS that documents the estimated impacts of 
regulatory alternatives under consideration. The SEIS accompanying this 
NPRM documents changes in emission inventories as estimated using the 
CAFE Model, but also documents corresponding estimates--based on the 
application of other models documented in the SEIS, of impacts on the 
global climate, on tropospheric air quality, and on human health.
    Other Aspects of Compliance: Beyond these statutory requirements 
applicable to DOT and/or EPA are a number of specific technical 
characteristics of CAFE and/or CO<INF>2</INF> regulations that are also 
relevant to the construction of this analysis. For example, EPA has 
defined procedures for calculating average CO<INF>2</INF> levels, and 
has revised procedures for calculating CAFE levels, to reflect 
manufacturers' application of ``off-cycle'' technologies that increase 
fuel economy (and reduce CO<INF>2</INF> emissions). Although too little 
information is available to account for these provisions explicitly in 
the same way that the agency has accounted for other technologies, the 
CAFE Model does include and makes use of inputs reflecting the agency's 
expectations regarding the extent to which manufacturers may earn such 
credits, along with estimates of corresponding costs. Similarly, the 
CAFE Model includes and makes use of inputs regarding credits EPA has 
elected to allow manufacturers to earn toward CO<INF>2</INF> levels 
(not CAFE) based on the use of air conditioner refrigerants with lower 
global warming potential (GWP), or on the application of technologies 
to reduce refrigerant leakage. In addition, the CAFE Model accounts for 
EPA ``multipliers'' for certain alternative fueled vehicles, based on 
current regulatory provisions or on alternative approaches. Although 
these are examples of regulatory provisions that arise from the 
exercise of discretion rather than specific statutory mandate, they can 
materially impact outcomes.
    Besides the updates to the model described above, any analysis of 
regulatory actions that will be implemented several years in the 
future, and whose benefits and costs accrue over decades, requires a 
large number of assumptions. Over such time horizons, many, if not 
most, of the relevant assumptions in such an analysis are inevitably 
uncertain. Each successive CAFE analysis seeks to update assumptions to 
reflect better the current state of the world and the best current 
estimates of future conditions.
    A number of assumptions have been updated since the 2020 final rule 
for this proposal. While NHTSA would have made these updates as a 
matter of course, we note that that the COVID-19 pandemic has been 
profoundly disruptive, including in ways directly material to major 
analytical inputs such as fuel prices, gross domestic product (GDP), 
vehicle production and sales, and highway travel. As discussed below, 
NHTSA has updated its ``analysis fleet'' from a model year 2017 
reference to a model year 2020 reference, updated estimates of 
manufacturers' compliance credit ``holdings,'' updated fuel price 
projections to reflect the U.S. Energy Information Administration's 
(EIA's) 2021 Annual Energy Outlook (AEO), updated projections of GDP 
and related macroeconomic measures, and updated projections of future 
highway travel. In addition, through Executive Order 13990, President 
Biden has required the formation of an Interagency Working Group (IWG) 
on the Social Cost of Greenhouse Gases and charged this body with 
updating estimates of the social costs of carbon, nitrous oxide, and 
methane. As discussed in the TSD, NHTSA has applied the IWG's interim 
guidance, which contains cost estimates (per ton of emissions) 
considerably greater than those applied in the analysis supporting the 
2020 SAFE rule. These and other updated analytical inputs are discussed 
in detail in the TSD. NHTSA seeks comment on the above discussion.

B. What is NHTSA analyzing?

    As in the CAFE and CO<INF>2</INF> rulemakings in 2010, 2012, and 
2020, NHTSA is proposing to set attribute-based CAFE standards defined 
by a mathematical function of vehicle footprint, which has observable 
correlation with fuel economy. EPCA, as amended by EISA, expressly 
requires that CAFE standards for passenger cars and light trucks be 
based on one or more vehicle attributes related to fuel economy and be 
expressed in the form of a mathematical function.\35\ Thus, the 
proposed standards (and regulatory alternatives) take the form of fuel 
economy targets expressed as functions of vehicle footprint (the 
product of vehicle wheelbase and average track width) that are separate 
for passenger cars and light trucks. Chapter 1.2.3 of the TSD discusses 
in detail NHTSA's continued

[[Page 49628]]

reliance on footprint as the relevant attribute in this proposal.
---------------------------------------------------------------------------

    \35\ 49 U.S.C. 32902(a)(3)(A).
---------------------------------------------------------------------------

    Under the footprint-based standards, the function defines a fuel 
economy performance target for each unique footprint combination within 
a car or truck model type. Using the functions, each manufacturer thus 
will have a CAFE average standard for each year that is almost 
certainly unique to each of its fleets,\36\ based upon the footprints 
and production volumes of the vehicle models produced by that 
manufacturer. A manufacturer will have separate footprint-based 
standards for cars and for trucks, consistent with 49 U.S.C. 32902(b)'s 
direction that NHTSA must set separate standards for cars and for 
trucks. The functions are mostly sloped, so that generally, larger 
vehicles (i.e., vehicles with larger footprints) will be subject to 
lower mpg targets than smaller vehicles. This is because, generally 
speaking, smaller vehicles are more capable of achieving higher levels 
of fuel economy, mostly because they tend not to have to work as hard 
(and therefore require as much energy) to perform their driving task. 
Although a manufacturer's fleet average standards could be estimated 
throughout the model year based on the projected production volume of 
its vehicle fleet (and are estimated as part of EPA's certification 
process), the standards with which the manufacturer must comply are 
determined by its final model year production figures. A manufacturer's 
calculation of its fleet average standards, as well as its fleets' 
average performance at the end of the model year, will thus be based on 
the production-weighted average target and performance of each model in 
its fleet.\37\
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    \36\ EPCA/EISA requires NHTSA and EPA to separate passenger cars 
into domestic and import passenger car fleets for CAFE compliance 
purposes (49 U.S.C. 32904(b)), whereas EPA combines all passenger 
cars into one fleet.
    \37\ As discussed in prior rulemakings, a manufacturer may have 
some vehicle models that exceed their target and some that are below 
their target. Compliance with a fleet average standard is determined 
by comparing the fleet average standard (based on the production-
weighted average of the target levels for each model) with fleet 
average performance (based on the production-weighted average of the 
performance of each model).
---------------------------------------------------------------------------

    For passenger cars, consistent with prior rulemakings, NHTSA is 
proposing to define fuel economy targets as shown in Equation III-1.
[GRAPHIC] [TIFF OMITTED] TP03SE21.030

Where:

TARGETFE is the fuel economy target (in mpg) applicable to a 
specific vehicle model type with a unique footprint combination,
a is a minimum fuel economy target (in mpg),
b is a maximum fuel economy target (in mpg),
c is the slope (in gallons per mile per square foot, or gpm, per 
square foot) of a line relating fuel consumption (the inverse of 
fuel economy) to footprint, and
d is an intercept (in gpm) of the same line.
Here, MIN and MAX are functions that take the minimum and maximum 
values, respectively, of the set of included values. For example, 
MIN[40, 35] = 35 and MAX(40, 25) = 40, such that MIN[MAX(40, 25), 
35] = 35.

    For the preferred alternative, this equation is represented 
graphically as the curves in Figure III-2.
BILLING CODE 4910-59-P

[[Page 49629]]

[GRAPHIC] [TIFF OMITTED] TP03SE21.031

    For light trucks, also consistent with prior rulemakings, NHTSA is 
proposing to define fuel economy targets as shown in Equation III-2.
[GRAPHIC] [TIFF OMITTED] TP03SE21.032

Where:

TARGETFE is the fuel economy target (in mpg) applicable to a 
specific vehicle model type with a unique footprint combination,
a, b, c, and d are as for passenger cars, but taking values specific 
to light trucks,
e is a second minimum fuel economy target (in mpg),
f is a second maximum fuel economy target (in mpg),
g is the slope (in gpm per square foot) of a second line relating 
fuel consumption (the inverse of fuel economy) to footprint, and
h is an intercept (in gpm) of the same second line.

    For the preferred alternative, this equation is represented 
graphically as the curves in Figure III-3.

[[Page 49630]]

[GRAPHIC] [TIFF OMITTED] TP03SE21.033

BILLING CODE 4910-59-C
    Although the general model of the target function equation is the 
same for each vehicle category (passenger cars and light trucks) and 
each model year, the parameters of the function equation differ for 
cars and trucks. The actual parameters for both the preferred 
alternative and the other regulatory alternatives are presented in 
Section IV.B of this preamble.
    As has been the case since NHTSA began establishing attribute-based 
standards, no vehicle need meet the specific applicable fuel economy 
target, because compliance with CAFE standards is determined based on 
corporate average fuel economy. In this respect, CAFE standards are 
unlike, for example, Federal Motor Vehicle Safety Standards (FMVSS) and 
certain vehicle criteria pollutant emissions standards where each car 
must meet the requirements. CAFE standards apply to the average fuel 
economy levels achieved by manufacturers' entire fleets of vehicles 
produced for sale in the U.S. Safety standards apply on a vehicle-by-
vehicle basis, such that every single vehicle produced for sale in the 
U.S. must, on its own, comply with minimum FMVSS. When first mandating 
CAFE standards in the 1970s, Congress specified a more flexible 
averaging-based approach that allows some vehicles to ``under comply'' 
(i.e., fall short of the overall flat standard, or fall short of their 
target under attribute-based standards) as long as a manufacturer's 
overall fleet is in compliance.
    The required CAFE level applicable to a given fleet in a given 
model year is determined by calculating the production-weighted 
harmonic average of fuel economy targets applicable to specific vehicle 
model configurations in the fleet, as shown in Equation III-3.

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[GRAPHIC] [TIFF OMITTED] TP03SE21.034

Where:

CAFErequired is the CAFE level the fleet is required to achieve,
i refers to specific vehicle model/configurations in the fleet,
PRODUCTIONi is the number of model configuration i produced for sale 
in the U.S., and
TARGETFE,I is the fuel economy target (as defined above) for model 
configuration i.

    Chapter 1 of the TSD describes the use of attribute-based 
standards, generally, and explains the specific decision, in past rules 
and for the current rule, to continue to use vehicle footprint as the 
attribute over which to vary stringency. That chapter also discusses 
the policy in selecting the specific mathematical function; the 
methodologies used to develop the current attribute-based standards; 
and methodologies previously used to reconsider the mathematical 
function for CAFE standards. NHTSA refers readers to the TSD for a full 
discussion of these topics.
    While Chapter 1 of the TSD explains why the proposed standards for 
MYs 2024-2026 continue to be footprint-based, the question has arisen 
periodically of whether NHTSA should instead consider multi-attribute 
standards, such as those that also depend on weight, torque, power, 
towing capability, and/or off-road capability. To date, every time 
NHTSA has considered options for which attribute(s) to select, the 
agency has concluded that a properly-designed footprint-based approach 
provides the best means of achieving the basic policy goals (i.e., by 
increasing the likelihood of improved fuel economy across the entire 
fleet of vehicles; by reducing disparities between manufacturers' 
compliance burdens; and by reducing incentives for manufacturers to 
respond to standards in ways that could compromise overall highway 
safety) involved in applying an attribute-based standard. At the same 
time, footprint-based standards need also to be structured in a way 
that furthers the energy and environmental policy goals of EPCA without 
creating inappropriate incentives to increase vehicle size in ways that 
could increase fuel consumption or compromise safety. That said, as 
NHTSA moves forward with the CAFE program, and continues to refine our 
understanding of the light-duty vehicle market and trends in vehicle 
and highway safety, NHTSA will also continue to revisit whether other 
approaches (or other ways of applying the same basic approaches) could 
foreseeably provide better means of achieving policy goals.
    For example, in the 2021 NAS Report, the committee recommended that 
if Congress does not act to remove the prohibition at 49 U.S.C. 
32902(h) on considering the fuel economy of dedicated alternative fuel 
vehicles (like BEVs) in determining maximum feasible CAFE standards, 
then NHTSA should account for the fuel economy benefits of ZEVs by 
``setting the standard as a function of a second attribute in addition 
to footprint--for example, the expected market share of ZEVs in the 
total U.S. fleet of new light-duty vehicles--such that the standards 
increase as the share of ZEVs in the total U.S. fleet increases.'' \38\ 
DOE seconded this suggestion in its comments during interagency review 
of this proposal. Chapter 1 of the TSD contains an examination of this 
suggestion, and NHTSA seeks comment on whether and how NHTSA might 
consider adding electrification as an attribute on which to base CAFE 
standards.
---------------------------------------------------------------------------

    \38\ National Academies of Sciences, Engineering, and Medicine, 
2021. Assessment of Technologies for Improving Fuel Economy of 
Light-Duty Vehicles--2025-2035, Washington, DC: The National 
Academies Press (hereafter, ``2021 NAS Report''), at Summary 
Recommendation 5. Available at <a href="https://www.nationalacademies.org/our-work/assessment-of-technologies-for-improving-fuel-economy-of-light-duty-vehicles-phase-3">https://www.nationalacademies.org/our-work/assessment-of-technologies-for-improving-fuel-economy-of-light-duty-vehicles-phase-3</a> and for hard-copy review at DOT 
headquarters.
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    Changes in the market that have occurred since NHTSA last examined 
the appropriateness of the footprint curves have been, for the most 
part, consistent with the trends that the agency identified in 2018. 
For the most part, the fleet has continued to grow somewhat in vehicle 
size, as vehicle manufacturers have continued over the past several 
years to reduce their offerings of smaller footprint vehicles and 
increase their sales of larger footprint vehicles and continue to sell 
many small to mid-size crossovers and SUVs, some of which are 
classified as passenger cars and some of which are light trucks. 
Although this trend has had the effect of reducing the achieved fuel 
economy of the fleet (and thus increasing its carbon dioxide emissions) 
as compared to if vehicles had instead remained the same size or gotten 
smaller, NHTSA does not believe that there have been sufficiently major 
changes in the relationship between footprint and fuel economy over the 
last three years to warrant a detailed re-examination of that 
relationship as part of this proposal. Moreover, changes to the 
footprint curves can significantly affect manufacturers' ability to 
comply. Given the available lead time between now and the beginning of 
MY 2024, NHTSA believes it is unlikely any potential benefit of 
changing the shape of the footprint curves (when we are already 
proposing to change standard stringency) would outweigh the costs of 
doing so.
    NHTSA seeks comment on the choice of footprint as the attribute on 
which the proposed standards are based, and particularly seeks comment 
on the 2021 NAS report recommendation described above. If commenters 
wish to provide comments on possible changes to the attribute(s) on 
which fuel economy standards should be based, including approaches for 
considering vehicle electrification in ways that would further a zero 
emissions fleet as discussed in Chapter 1 of the TSD, NHTSA would 
appreciate commenters including a discussion of the timeframe in which 
those changes should be made--for example, whether and how much lead 
time would be preferable for making such changes, particularly 
recognizing the available lead time for MY 2024. NHTSA also seeks 
comment on whether, to the extent that vehicle upsizing trends and fuel 
economy curves are causally related instead of correlated, it is the 
curve shape versus the choice of footprint that creates this 
relationship (or, alternatively, whether the relationship if any 
derives from vehicle classification). Again, if commenters wish to 
provide comments on possible changes to the curve shapes, NHTSA would 
appreciate commenters including a discussion of the timeframe in which 
those changes should be made.
    NHTSA seeks comment on the discussion above and in the TSD.

[[Page 49632]]

C. What inputs does the compliance analysis require?

    The CAFE Model applies various technologies to different vehicle 
models in each manufacturer's product line to simulate how each 
manufacturer might make progress toward compliance with the specified 
standard. Subject to a variety of user-controlled constraints, the 
model applies technologies based on their relative cost-effectiveness, 
as determined by several input assumptions regarding the cost and 
effectiveness of each technology, the cost of compliance (determined by 
the change in CAFE or CO<INF>2</INF> credits, CAFE-related civil 
penalties, or value of CO<INF>2</INF> credits, depending on the 
compliance program being evaluated), and the value of avoided fuel 
expenses. For a given manufacturer, the compliance simulation algorithm 
applies technologies either until the manufacturer runs out of cost-
effective technologies,\39\ until the manufacturer exhausts all 
available technologies, or, if the manufacturer is assumed to be 
willing to pay civil penalties or acquire credits from another 
manufacturer, until paying civil penalties or purchasing credits 
becomes more cost-effective than increasing vehicle fuel economy. At 
this stage, the system assigns an incurred technology cost and updated 
fuel economy to each vehicle model, as well as any civil penalties 
incurred/credits purchased by each manufacturer. This compliance 
simulation process is repeated for each model year included in the 
study period (through model year 2050 in this analysis).
---------------------------------------------------------------------------

    \39\ Generally, the model considers a technology cost-effective 
if it pays for itself in fuel savings within 30 months. Depending on 
the settings applied, the model can continue to apply technologies 
that are not cost-effective rather than choosing other compliance 
options; if it does so, it will apply those additional technologies 
in order of cost-effectiveness (i.e., most cost-effective first).
---------------------------------------------------------------------------

    At the conclusion of the compliance simulation for a given 
regulatory scenario the system transitions between compliance 
simulation and effects calculations. This is the point where the system 
produces a full representation of the registered light-duty vehicle 
population in the United States. The CAFE Model then uses this fleet to 
generate estimates of the following (for each model year and calendar 
year included in the analysis): Lifetime travel, fuel consumption, 
carbon dioxide and criteria pollutant emissions, the magnitude of 
various economic externalities related to vehicular travel (e.g., 
congestion and noise), and energy consumption (e.g., the economic costs 
of short-term increases in petroleum prices, or social damages 
associated with GHG emissions). The system then uses these estimates to 
measure the benefits and costs associated with each regulatory 
alternative (relative to the no-action alternative).
    To perform this analysis, the CAFE Model uses millions of data 
points contained in several input files that have been populated by 
engineers, economists, and safety and environmental program analysts at 
both NHTSA and the DOT's Volpe National Transportations Systems Center 
(Volpe). In addition, some of the input data comes from modeling and 
simulation analysis performed by experts at Argonne National Laboratory 
using their Autonomie full vehicle simulation model and BatPaC battery 
cost model. Other inputs are derived from other models, such as the 
U.S. Energy Information Administration's (EIA's) National Energy 
Modeling System (NEMS), Argonne's ``GREET'' fuel-cycle emissions 
analysis model, and U.S. EPA's ``MOVES'' vehicle emissions analysis 
model. As NHTSA and Volpe are both organizations within DOT, we use DOT 
throughout these sections to refer to the collaborative work performed 
for this analysis.
    This section and Section III.D describe the inputs that the 
compliance simulation requires, including an in-depth discussion of the 
technologies used in the analysis, how they are defined in the CAFE 
Model, how they are characterized on vehicles that already exist in the 
market, how they can be applied to realistically simulate 
manufacturer's decisions, their effectiveness, and their cost. The 
inputs and analyses for the effects calculations, including economic, 
safety, and environmental effects, are discussed later in Sections 
III.C through III.H. NHTSA seeks comment on the following discussion.
1. Overview of Inputs to the Analysis
    As discussed above, the current analysis involves estimating four 
major swaths of effects. First, the analysis estimates how the 
application of various combinations of technologies could impact 
vehicles' costs and fuel economy levels (and CO<INF>2</INF> emission 
rates). Second, the analysis estimates how vehicle manufacturers might 
respond to standards by adding fuel-saving technologies to new 
vehicles. Third, the analysis estimates how changes in new vehicles 
might impact vehicle sales and operation. Finally, the analysis 
estimates how the combination of these changes might impact national-
scale energy consumption, emissions, highway safety, and public health.
    There are several CAFE Model input files important to the 
discussion these first two steps, and these input files are discussed 
in detail later in this section and in Section III.D. The Market Data 
file contains the detailed description of the vehicle models and model 
configurations each manufacturer produces for sale in the U.S. The file 
also contains a range of other inputs that, though not specific to 
individual vehicle models, may be specific to individual manufacturers. 
The Technologies file identifies about six dozen technologies to be 
included in the analysis, indicates when and how widely each technology 
can be applied to specific types of vehicles, provides most of the 
inputs involved in estimating what costs will be incurred, and provides 
some of the inputs involved in estimating impacts on vehicle fuel 
consumption and weight.
    The CAFE Model also makes use of databases of estimates of fuel 
consumption impacts and, as applicable, battery costs for different 
combinations of fuel saving technologies.\40\ These databases are 
termed the FE1 and FE2 Adjustments databases (the main database and the 
database specific to plug-in hybrid electric vehicles, applicable to 
those vehicles' operation on electricity) and the Battery Costs 
database. DOT developed these databases using a large set of full 
vehicle and accompanying battery cost model simulations developed by 
Argonne National Laboratory. The Argonne simulation outputs, battery 
costs, and other reference materials are also discussed in the 
following sections.\41\
---------------------------------------------------------------------------

    \40\ To be used as files provided separately from the model and 
loaded every time the model is executed, these databases are 
prohibitively large, spanning more than a million records and more 
than half a gigabyte. To conserve memory and speed model operation, 
DOT has integrated the databases into the CAFE Model executable 
file. When the model is run, however, the databases are extracted 
and placed in an accessible location on the user's disk drive.
    \41\ The Argonne workbooks included in the docket for this 
proposal include ten databases that contain the outputs of the 
Autonomie full vehicle simulations, two summary workbooks of 
assumptions used for the full vehicle simulations, a data 
dictionary, and the lookup tables for battery costs generated using 
the BatPaC battery cost model.
---------------------------------------------------------------------------

    The following discussion in this section and in Section III.D 
expands on the inputs used in the compliance analysis. Further detail 
is included in Chapters 2 and 3 of the TSD accompanying this proposal, 
and all input values relevant to the compliance analysis can be seen in 
the Market Data, Technologies, fuel consumption and battery cost 
database files, and Argonne

[[Page 49633]]

summary files included in the docket for this proposal. As previously 
mentioned, other model input files underlie the effects analysis, and 
these are discussed in detail in Sections III.C through III.H. NHTSA 
seeks comment on the above discussion.
2. The Market Data File
    The Market Data file contains the detailed description of the 
vehicle models and model configurations each manufacturer produces for 
sale in the U.S. This snapshot of the recent light duty vehicle market, 
termed the analysis fleet, or baseline fleet, is the starting point for 
the evaluation of different stringency levels for future fuel economy 
standards. The analysis fleet provides a reference from which to 
project how manufacturers could apply additional technologies to 
vehicles to cost-effectively improve vehicle fuel economy, in response 
to regulatory action and market conditions.\42\ For this analysis, the 
MY 2020 light duty fleet was selected as the baseline for further 
evaluation of the effects of different fuel economy standards. The 
Market Data file also contains a range of other inputs that, though not 
specific to individual vehicle models, may be specific to individual 
manufacturers.
---------------------------------------------------------------------------

    \42\ The CAFE Model does not generate compliance paths a 
manufacturer should, must, or will deploy. It is intended as a tool 
to demonstrate a compliance pathway a manufacturer could choose. It 
is almost certain all manufacturers will make compliance choices 
differing from those projected by the CAFE Model.
---------------------------------------------------------------------------

    The Market Data file is an Excel spreadsheet that contains five 
worksheets. Three worksheets, the Vehicles worksheet, Engines 
worksheet, and Transmissions worksheet, characterize the baseline fleet 
for this analysis. The three worksheets contain a characterization of 
every vehicle sold in MY 2020 and their relevant technology content, 
including the engines and transmissions that a manufacturer uses in its 
vehicle platforms and how those technologies are shared across 
platforms. In addition, the Vehicles worksheet includes baseline 
economic and safety inputs linked to each vehicle that allow the CAFE 
Model to estimate economic and safety impacts resulting from any 
simulated compliance pathway. The remaining two worksheets, the 
Manufacturers worksheet and Credits and Adjustments worksheet, include 
baseline compliance positions for each manufacturer, including each 
manufacturer's starting CAFE credit banks and whether the manufacturer 
is willing to pay civil penalties for noncompliance with CAFE 
standards, among other inputs.
    New inputs have been added for this analysis in the Vehicles 
worksheet and Manufacturers worksheet. The new inputs indicate which 
vehicles a manufacturer may reasonably be expected to convert to a zero 
emissions vehicle (ZEV) at first redesign opportunity, to comply with 
several States' ZEV program provisions. The new inputs also indicate if 
a manufacturer has entered into an agreement with California to achieve 
more stringent CO<INF>2</INF> emissions reductions targets than those 
promulgated in the 2020 final rule.
    The following sections discuss how we built the Market Data file, 
including characterizing vehicles sold in MY 2020 and their technology 
content, and baseline safety, economic, and manufacturer compliance 
positions. A detailed discussion of the Market Data file development 
process is in TSD Chapter 2.2. NHTSA seeks comment on the below 
discussion and the agency's approach to developing the Market Data file 
for this proposal.
(a) Characterizing Vehicles and Their Technology Content
    The Market Data file integrates information from many sources, 
including manufacturer compliance submissions, publicly available 
information, and confidential business information. At times, DOT must 
populate inputs using analyst judgment, either because information is 
still incomplete or confidential, or because the information does not 
yet exist.\43\ For this analysis DOT uses mid-model year 2020 
compliance data as the basis of the analysis fleet. The compliance data 
is supplemented for each vehicle nameplate with manufacturer 
specification sheets, usually from the manufacturer media website, or 
from online marketing brochures.\44\ For additional information about 
how specification sheets inform MY 2020 vehicle technology assignments, 
see the technology specific assignments sections in Section III.D.
---------------------------------------------------------------------------

    \43\ Forward looking refresh/redesign cycles are one example of 
when analyst judgement is necessary.
    \44\ The catalogue of reference specification sheets (broken 
down by manufacturer, by nameplate) used to populate information in 
the market data file is available in the docket.
---------------------------------------------------------------------------

    DOT uses the mid-model year 2020 compliance data to create a row on 
the Vehicles worksheet in the Market Data file for each vehicle (or 
vehicle variant \45\) that lists a certification fuel economy, sales 
volume, regulatory class, and footprint. DOT identifies which 
combination of modeled technologies reasonably represents the fuel 
saving technologies already on each vehicle, and assigns those 
technologies to each vehicle, either on the Vehicles worksheet, the 
Engines worksheet, or the Transmissions worksheet. The fuel saving 
technologies considered in this analysis are listed in Table III-1.
---------------------------------------------------------------------------

    \45\ The market data file often includes a few rows for vehicles 
that may have identical certification fuel economies, regulatory 
classes, and footprints (with compliance sales volumes divided out 
among rows), because other pieces of information used in the CAFE 
Model may be dissimilar. For instance, in the reference materials 
used to create the Market Data file, for a nameplate curb weight may 
vary by trim level (with premium trim levels often weighing more on 
account of additional equipment on the vehicle), or a manufacturer 
may provide consumers the option to purchase a larger fuel tank size 
for their vehicle. These pieces of information may not impact the 
observed compliance position directly, but curb weight (in relation 
to other vehicle attributes) is important to assess mass reduction 
technology already used on the vehicle, and fuel tank size is 
directly relevant to saving time at the gas pump, which the CAFE 
Model uses when calculating the value of avoided time spent 
refueling.
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BILLING CODE 4910-59-P

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[[Page 49635]]


[GRAPHIC] [TIFF OMITTED] TP03SE21.036


[[Page 49636]]


[GRAPHIC] [TIFF OMITTED] TP03SE21.037

BILLING CODE 4910-59-C
    For additional information on the characterization of these 
technologies (including the cost, prevalence in the 2020 fleet, 
effectiveness estimates, and considerations for their adoption) see the 
appropriate technology section in Section III.D or TSD Chapter 3.
    DOT also assigns each vehicle a technology class. The CAFE Model 
uses the technology class (and engine class, discussed below) in the 
Market Data file to reference the most relevant technology costs for 
each vehicle, and fuel saving technology combinations. We assign each 
vehicle in the fleet a technology class using a two-step algorithm that 
takes into account key characteristics of vehicles in the fleet 
compared to the baseline characteristics of each technology class.\46\ 
As discussed further in Section III.C.4.b), there are ten technology 
classes used in the CAFE analysis that span five vehicle types and two 
performance variants. The

[[Page 49637]]

technology class algorithm and assignment process is discussed in more 
detail in TSD Chapter 2.4.2.
---------------------------------------------------------------------------

    \46\ Baseline 0 to 60 mph accelerations times are assumed for 
each technology class as part of the Autonomie full vehicle 
simulations. DOT calculates class baseline curb weights and 
footprints by averaging the curb weights and footprints of vehicles 
within each technology class as assigned in previous analyses.
---------------------------------------------------------------------------

    We also assign each vehicle an engine technology class so that the 
CAFE Model can reference the powertrain costs in the Technologies file 
that most reasonably align with the observed vehicle. DOT assigns 
engine technology classes for all vehicles, including electric 
vehicles. If an electric powertrain replaces and internal combustion 
engine, the electric motor specifications may be different (and hence 
costs may be different) depending on the capabilities of the internal 
combustion engine it is replacing, and the costs in the technologies 
file (on the engine tab) account for the power output and capability of 
the gasoline or electric drivetrain.
    Parts sharing helps manufacturers achieve economies of scale, 
deploy capital efficiently, and make the most of shared research and 
development expenses, while still presenting a wide array of consumer 
choices to the market. The CAFE Model simulates part sharing by 
implementing shared engines, shared transmissions, and shared mass 
reduction platforms. Vehicles sharing a part (as recognized in the CAFE 
Model), will adopt fuel saving technologies affecting that part 
together. To account for parts sharing across products, vehicle model/
configurations that share engines are assigned the same engine 
code,\47\ vehicle model/configurations that share transmissions have 
the same transmission code, and vehicles that adopt mass reduction 
technologies together share the same platform. For more information 
about engine codes, transmission codes, and mass reduction platforms 
see TSD Chapter 3.
---------------------------------------------------------------------------

    \47\ Engines (or transmissions) may not be exactly identical, as 
specifications or vehicle integration features may be different. 
However, the architectures are similar enough that it is likely the 
powertrain systems share research and development (R&D), tooling, 
and production resources in a meaningful way.
---------------------------------------------------------------------------

    Manufacturers often introduce fuel saving technologies at a major 
redesign of their product or adopt technologies at minor refreshes in 
between major product redesigns. To support the CAFE Model accounting 
for new fuel saving technology introduction as it relates to product 
lifecycle, the Market Data file includes a projection of redesign and 
refresh years for each vehicle. DOT projects future redesign years and 
refresh years based on the historical cadence of that vehicle's product 
lifecycle. For new nameplates, DOT considers the manufacturer's 
treatment of product lifecycles for past products in similar market 
segments. When considering year-by-year analysis of standards, the 
sizing of redesign and refresh intervals will affect projected 
compliance pathways and how quickly manufacturers can respond to 
standards. TSD Chapter 2.2.1.7 includes additional information about 
the product design cycles assumed for this proposal based on historical 
manufacturer product design cycles.
    The Market Data file also includes information about air 
conditioning (A/C) and off-cycle technologies, but the information is 
not currently broken out at a row level, vehicle by vehicle.\48\ 
Instead, historical data (and forecast projections, which are used for 
analysis regardless of regulatory scenario) are listed by manufacturer, 
by fleet on the Credits and Adjustments worksheet of the Market Data 
file. Section III.D.8 shows model inputs specifying estimated 
adjustments (all in grams/mile) for improvements to air conditioner 
efficiency and other off-cycle energy consumption, and for reduced 
leakage of air conditioner refrigerants with high global warming 
potential (GWP). DOT estimated future values based on an expectation 
that manufacturers already relying heavily on these adjustments would 
continue do so, and that other manufacturers would, over time, also 
approach the limits on adjustments allowed for such improvements.
---------------------------------------------------------------------------

    \48\ Regulatory provisions regarding off-cycle technologies are 
new, and manufacturers have only recently begun including related 
detailed information in compliance reporting data. For this 
analysis, though, such information was not sufficiently complete to 
support a detailed representation of the application of off-cycle 
technology to specific vehicle model/configurations in the MY 2020 
fleet.
---------------------------------------------------------------------------

(b) Characterizing Baseline Safety, Economic, and Compliance Positions
    In addition to characterizing vehicles and their technology 
content, the Market Data file contains a range of other inputs that, 
though not specific to individual vehicle models, may be specific to 
individual manufacturers, or that characterize baseline safety or 
economic information.
    First, the CAFE Model considers the potential safety effect of mass 
reduction technologies and crash compatibility of different vehicle 
types. Mass reduction technologies lower the vehicle's curb weight, 
which may improve crash compatibility and safety, or not, depending on 
the type of vehicle. DOT assigns each vehicle in the Market Data file a 
safety class that best aligns with the mass-size-safety analysis. This 
analysis is discussed in more detail in Section III.H of this proposal 
and TSD Chapter 7.
    The CAFE Model also includes procedures to consider the direct 
labor impacts of manufacturer's response to CAFE regulations, 
considering the assembly location of vehicles, engines, and 
transmissions, the percent U.S. content (that reflects percent U.S. and 
Canada content),\49\ and the dealership employment associated with new 
vehicle sales. The Market Data file therefore includes baseline labor 
information, by vehicle. Sales volumes also influence total estimated 
direct labor projections in the analysis.
---------------------------------------------------------------------------

    \49\ Percent U.S. content was informed by the 2020 Part 583 
American Automobile Labeling Act Reports, appearing on NHTSA's 
website.
---------------------------------------------------------------------------

    We hold the percent U.S. content constant for each vehicle row for 
the duration of the analysis. In practice, this may not be the case. 
Changes to trade policy and tariff policy may affect percent U.S. 
content in the future. Also, some technologies may be more or less 
likely to be produced in the U.S., and if that is the case, their 
adoption could affect future U.S. content. NHTSA does not have data at 
this time to support varying the percent U.S. content.
    We also hold the labor hours projected in the Market Data file per 
unit transacted at dealerships, per unit produced for final assembly, 
per unit produced for engine assembly, and per unit produced for 
transmission assembly constant for the duration of the analysis, and 
project that the origin of these activities to remain unchanged. In 
practice, it is reasonable to expect that plants could move locations, 
or engine and transmission technologies are replaced by another fuel 
saving technology (like electric motors and fixed gear boxes) that 
could require a meaningfully different amount of assembly labor hours. 
NHTSA does not have data at this time to support varying labor hours 
projected in the Market Data file, but we will continue to explore 
methods to estimate the direct labor impacts of manufacturer's 
responses to CAFE standards in future analyses.
    As observed from Table III-2, manufacturers employ U.S. labor with 
varying intensity. In many cases, vehicles certifying in the light 
truck (LT) regulatory class have a larger percent U.S. content than 
vehicles certifying in the passenger car (PC) regulatory class.

[[Page 49638]]

[GRAPHIC] [TIFF OMITTED] TP03SE21.038

    Next, manufacturers may over-comply with CAFE standards and bank 
so-called over compliance credits. As discussed further in Section 
III.C.7, manufacturers may use these credits later, sell them to other 
manufacturers, or let them expire. The CAFE Model does not explicitly 
trade credits between and among manufacturers, but staff have adjusted 
starting credit banks in the Market Data file to reflect trades that 
are likely to happen when the simulation begins (in MY 2020). 
Considering information manufacturers have reported regarding 
compliance credits, and considering recent manufacturers' compliance 
positions, DOT estimates manufacturers' potential use of compliance 
credits in earlier MYs. This aligns to an extent that represents how 
manufacturers could deplete their credit banks rather than producing 
high volume vehicles with fuel saving technologies in earlier MYs. This 
also avoids the unrealistic application of technologies for 
manufacturers in early analysis years that typically rely on credits. 
For a complete discussion about how this data is collected and assigned 
in the Market Data file, see TSD Chapter 2.2.2.3.
---------------------------------------------------------------------------

    \50\ Tesla does not have internal combustion engines, or multi-
speed transmissions, even though they are identified as producing 
engine and transmission systems in the United States in the Market 
Data file.
---------------------------------------------------------------------------

    The Market Data file also includes assumptions about a vehicle 
manufacturer's preferences towards civil penalty payments. EPCA 
requires that if a manufacturer does not achieve compliance with a CAFE 
standard in a given model year and cannot apply credits sufficient to 
cover the compliance shortfall, the manufacturer must pay civil 
penalties (i.e., fines) to the Federal Government. If inputs indicate 
that a manufacturer treats civil penalty payment as an economic choice 
(i.e., one to be taken if doing so would be economically preferable to 
applying further technology toward compliance), the CAFE Model, when 
evaluating the manufacturer's response to CAFE standards in a given 
model year, will apply fuel-saving technology only up to the point 
beyond which doing so would be more expensive (after subtracting the 
value of avoided fuel outlays) than paying civil penalties.
    For this analysis, DOT exercises the CAFE Model with inputs 
treating all manufacturers as treating civil penalty

[[Page 49639]]

payment as an economic choice through model year 2023. While DOT 
expects that only manufacturers with some history of paying civil 
penalties would actually treat civil penalty payment as an acceptable 
option, the CAFE Model does not currently simulate compliance credit 
trading between manufacturers, and DOT expects that this treatment of 
civil penalty payment will serve as a reasonable proxy for compliance 
credit purchases some manufacturers might actually make through model 
year 2023. These input assumptions for model years through 2023 reduce 
the potential that the model will overestimate technology application 
in the model years leading up to those for which the agency is 
proposing new standards. As in past CAFE rulemaking analyses (except 
that supporting the 2020 final rule), DOT has treated manufacturers 
with some history of civil penalty payment (i.e., BMW, Daimler, FCA, 
Jaguar-Land Rover, Volvo, and Volkswagen) as continuing to treat civil 
penalty payment as an acceptable option beyond model year 2023, but has 
treated all other manufacturers as unwilling to do so beyond model year 
2023.
    Next, the CAFE Model uses an ``effective cost'' metric to evaluate 
options to apply specific technologies to specific engines, 
transmissions, and vehicle model configurations. Expressed on a $/
gallon basis, the analysis computes this metric by subtracting the 
estimated values of avoided fuel outlays and civil penalties from the 
corresponding technology costs, and then dividing the result by the 
quantity of avoided fuel consumption. The analysis computes the value 
of fuel outlays over a ``payback period'' representing the 
manufacturer's expectation that the market will be willing to pay for 
some portion of fuel savings achieved through higher fuel economy. Once 
the model has applied enough technology to a manufacturer's fleet to 
achieve compliance with CAFE standards (and CO<INF>2</INF> standards 
and ZEV mandates) in a given model year, the model will apply any 
further fuel economy improvements estimated to produce a negative 
effective cost (i.e., any technology applications for which avoided 
fuel outlays during the payback period are larger than the 
corresponding technology costs). As discussed above in Section III.A 
and below in Section III.C, DOT anticipates that manufacturers are 
likely to act as if the market is willing to pay for avoided fuel 
outlays expected during the first 30 months of vehicle operation.
    We seek comment on whether this expectation is appropriate, or 
whether some other amount of time should be used. If commenters believe 
a different amount of time should be used for the payback assumption, 
it would be most helpful if commenters could define the amount of time, 
provide an explanation of why that amount of time is preferable, 
provide any data or information on which the amount of time is based, 
and provide any discussion of how changing this assumption would 
interact with other elements in the analysis.
    In addition, the Market Data file includes two new sets of inputs 
for this analysis. In 2020, five vehicle manufacturers reached a 
voluntary commitment with the state of California to improve the fuel 
economy of their future nationwide fleets above levels required by the 
2020 final rule. For this analysis, compliance with this agreement is 
in the baseline case for designated manufacturers. The Market Data file 
contains inputs indicating whether each manufacturer has committed to 
exceed Federal requirements per this agreement.
    Finally, when considering other standards that may affect fuel 
economy compliance pathways, DOT includes projected zero emissions 
vehicles (ZEV) that would be required for manufacturers to meet 
standards in California and Section 177 States, per the waiver granted 
under the Clean Air Act. To support the inclusion of the ZEV program in 
the analysis, DOT identifies specific vehicle model/configurations that 
could adopt BEV technology in response to the ZEV program, independent 
of CAFE standards, at the first redesign opportunity. These ZEVs are 
identified in the Market Data file as future BEV200s, BEV300s, or 
BEV400s. Not all announced BEV nameplates appear in the MY 2020 Market 
Data file; in these cases, in consultation with CARB, DOT used the 
volume from a comparable vehicle in the manufacturer's Market Data file 
portfolio as a proxy. The Market Data file also includes information 
about the portion of each manufacturer's sales that occur in California 
and Section 177 states, which is helpful for determining how many ZEV 
credits each manufacturer will need to generate in the future to comply 
with the ZEV program with their own portfolio in the rulemaking 
timeframe. These new procedures are described in detail below and in 
TSD Chapter 2.3.
3. Simulating the Zero Emissions Vehicle Program
    California's Zero Emissions Vehicle (ZEV) program is one part of a 
program of coordinated standards that the California Air Resources 
Board (CARB) has enacted to control emissions of criteria pollutants 
and greenhouse gas emissions from vehicles. The program began in 1990, 
within the low-emission vehicle (LEV) regulation,\51\ and has since 
expanded to include eleven other states.\52\ These states may be 
referred to as Section 177 states, in reference to Section 177 of the 
Clean Air Act's grant of authority to allow these states to adopt 
California's air quality standards,\53\ but it is important to note 
that not all Section 177 states have adopted the ZEV program 
component.\54\ In the following discussion of the incorporation of the 
ZEV program into the CAFE Model, any reference to the Section 177 
states refers to those states that have adopted California's ZEV 
program requirements.
---------------------------------------------------------------------------

    \51\ California Air Resource Board (CARB), Zero-Emission Vehicle 
Program. California Air Resources Board. Accessed April 12, 2021. 
<a href="https://ww2.arb.ca.gov/our-work/programs/zero-emission-vehicle-program/about">https://ww2.arb.ca.gov/our-work/programs/zero-emission-vehicle-program/about</a>.
    \52\ At the time of writing, the Section 177 states that have 
adopted the ZEV program are Colorado, Connecticut, Maine, Maryland, 
Massachusetts, New Jersey, New York, Oregon, Rhode Island, Vermont, 
and Washington. See Vermont Department of Environmental 
Conservation, Zero Emission Vehicles. Accessed April 12, 2021. 
https://dec.vermont.gov/air-quality/mobile-sources/
zev#:~:text=To%20date%2C%2012%20states%20have,ZEVs%20over%20the%20nex
t%20decade.
    \53\ Section 177 of the Clean Air Act allows other states to 
adopt California's air quality standards.
    \54\ At the time of writing, Delaware and Pennsylvania are the 
two states that have adopted the LEV standards, but not the ZEV 
portion.
---------------------------------------------------------------------------

    To account for the ZEV program, and particularly as other states 
have recently adopted California's ZEV standards, DOT includes the main 
provisions of the ZEV program in the CAFE Model's analysis of 
compliance pathways. As explained below, incorporating the ZEV program 
into the model includes converting vehicles that have been identified 
as potential ZEV candidates into battery-electric vehicles (BEVs) at 
the first redesign opportunity, so that a manufacturer's fleet meets 
calculated ZEV credit requirements. Since ZEV program compliance 
pathways happen independently from the adoption of fuel saving 
technology in response to increasing CAFE standards, the ZEV program is 
considered in the baseline of the analysis, and in all other regulatory 
alternatives.
    Through its ZEV program, California requires that all manufacturers 
that sell cars within the state meet ZEV credit standards. The current 
credit requirements are calculated based on manufacturers' California 
sales volumes. Manufacturers primarily earn ZEV credits through the 
production of BEVs, fuel cell vehicles (FCVs), and

[[Page 49640]]

transitional zero-emissions vehicles (TZEVs), which are vehicles with 
partial electrification, namely plug-in hybrids (PHEVs). Total credits 
are calculated by multiplying the credit value each ZEV receives by the 
vehicle's volume.
    The ZEV and PHEV/TZEV credit value per vehicle is calculated based 
on the vehicle's range; ZEVs may earn up to 4 credits each and PHEVs 
with a US06 all-electric range capability of 10 mi or higher receive an 
additional 0.2 credits on top of the credits received based on all-
electric range.\55\ The maximum PHEV credit amount available per 
vehicle is 1.10.\56\ Note however that CARB only allows intermediate-
volume manufacturers to meet their ZEV credit requirements through PHEV 
production.\57\
---------------------------------------------------------------------------

    \55\ US06 is one of the drive cycles used to test fuel economy 
and all-electric range, specifically for the simulation of 
aggressive driving. See Dynamometer Drive Schedules [verbar] Vehicle 
and Fuel Emissions Testing [verbar] U.S. EPA for more information, 
as well as Section III.C.4 and Section III.D.3.d).
    \56\ 13 CCR 1962.2(c)(3).
    \57\ 13 CCR 1962.2(c)(3).
---------------------------------------------------------------------------

    DOT's method for simulating the ZEV program involves several steps; 
first, DOT calculates an approximate ZEV credit target for each 
manufacturer based on the manufacturer's national sales volumes, share 
of sales in Section 177 states, and the CARB credit requirements. Next, 
DOT identifies a general pathway to compliance that involves accounting 
for manufacturers' potential use of ZEV overcompliance credits or other 
credit mechanisms, and the likelihood that manufacturers would choose 
to comply with the requirements with BEVs rather than PHEVs or other 
types of compliant vehicles, in addition to other factors. For this 
analysis, as discussed further below, DOT consulted with CARB to 
determine reasonable assumptions for this compliance pathway. Finally, 
DOT identifies vehicles in the MY 2020 analysis fleet that 
manufacturers could reasonably adapt to comply with the ZEV standards 
at the first opportunity for vehicle redesign, based on publicly 
announced product plans and other information. Each of these steps is 
discussed in turn, below, and a more detailed description of DOT's 
simulation of the ZEV program is included in TSD Chapter 2.3.
    The CAFE Model is designed to present outcomes at a national scale, 
so the ZEV analysis considers the Section 177 states as a group as 
opposed to estimating each state's ZEV credit requirements 
individually. To capture the appropriate volumes subject to the ZEV 
requirement, DOT calculates each manufacturer's total market share in 
Section 177 states. DOT also calculates the overall market share of 
ZEVs in Section 177 states, in order to estimate as closely as possible 
the number of predicted ZEVs we expect all manufacturers to sell in 
those states. These shares are then used to scale down national-level 
information in the CAFE Model to ensure that we represent only Section 
177 states in the final calculation of ZEV credits that we project each 
manufacturer to earn in future years.
    DOT uses model year 2019 National Vehicle Population Profile (NVPP) 
from IHS Markit--Polk to calculate these percentages.\58\ These data 
include vehicle characteristics such as powertrain, fuel type, 
manufacturer, nameplate, and trim level, as well as the state in which 
each vehicle is sold, which allows staff to identify the different 
types of ZEVs manufacturers sell in the Section 177 state group. DOT 
may make use of future Polk data in updating the analysis for the final 
rule and may include other states that join the ZEV program after the 
publication of this proposal, if necessary.
---------------------------------------------------------------------------

    \58\ National Vehicle Population Profile (NVPP) 2020, IHS 
Markit--Polk. At the time of the analysis, model year 2019 data from 
the NVPP contained the most current estimate of market shares by 
manufacturer, and best represented the registered vehicle population 
on January 1, 2020.
---------------------------------------------------------------------------

    We calculate sales volumes for the ZEV credit requirement based on 
each manufacturer's future assumed market share in Section 177 states. 
DOT decided to carry each manufacturer's ZEV market shares forward to 
future years, after examination of past market share data from model 
year 2016, from the 2017 version of the NVPP.\59\ Comparison of these 
data to the 2020 version showed that manufacturers' market shares 
remain fairly constant in terms of geographic distribution. Therefore, 
we determined that it was reasonable to carry forward the recently 
calculated market shares to future years.
---------------------------------------------------------------------------

    \59\ National Vehicle Population Profile (NVPP) 2017, IHS 
Markit--Polk.
---------------------------------------------------------------------------

    We calculate total credits required for ZEV compliance by 
multiplying the percentages from CARB's ZEV requirement schedule by the 
Section 177 state volumes. CARB's credit percentage requirement 
schedule for the years covered in this analysis begins at 9.5% in 2020 
and ramps up in increments to 22% by 2025.\60\ Note that the 
requirements do not currently change after 2025.\61\
---------------------------------------------------------------------------

    \60\ See 13 CCR 1962.2(b). The percentage credit requirements 
are as follows: 9.5% in 2020, 12% in 2021, 14.5% in 2022, 17% in 
2023, 19.5% in 2024, and 22% in 2025 and onward.
    \61\ 13 CCR 1962.2(b).
---------------------------------------------------------------------------

    We generate national sales volume predictions for future years 
using the Compliance Report, a CAFE Model output file that includes 
simulated sales by manufacturer, fleet, and model year. We use a 
Compliance Report that corresponds to the baseline scenario of 1.5% per 
year increases in standards for both passenger car and light truck 
fleets. The resulting national sales volume predictions by manufacturer 
are then multiplied by each manufacturer's total market share in the 
Section 177 states to capture the appropriate volumes in the ZEV 
credits calculation. Required credits by manufacturer, per year, are 
determined by multiplying the Section 177 state volumes by CARB's ZEV 
credit percentage requirement. These required credits are subsequently 
added to the CAFE Model inputs as targets for manufacturer compliance 
with ZEV standards in the CAFE baseline.
    The estimated ZEV credit requirements serve as a target for 
simulating ZEV compliance in the baseline. To achieve this, DOT 
determines a modeling philosophy for ZEV pathways, reviews various 
sources for information regarding upcoming ZEV programs, and inserts 
those programs into the analysis fleet inputs. As manufacturers can 
meet ZEV standards in a variety of different ways, using various 
technology combinations, the analysis must include certain simplifying 
assumptions in choosing ZEV pathways. We made these assumptions in 
conjunction with guidance from CARB staff. The following sections 
discuss the approach used to simulate a pathway to ZEV program 
compliance in this analysis.
    First, DOT targeted 2025 compliance, as opposed to assuming 
manufacturers would perfectly comply with their credit requirements in 
each year prior to 2025. This simplifying assumption was made upon 
review of past history of ZEV credit transfers, existing ZEV credit 
banks, and redesign schedules. DOT focused on integrating ZEV 
technology throughout that timeline with the target of meeting 2025 
obligations; thus, some manufacturers are estimated to over-comply or 
under-comply, depending on their individual situations, in the years 
2021-2024.
    Second, DOT determined that the most reasonable way to model ZEV 
compliance would be to allow under-compliance in certain cases and 
assume that some manufacturers would not meet their ZEV obligation on 
their own in 2025. Instead, these manufacturers were assumed to prefer 
to purchase credits from another manufacturer with a credit surplus. 
Reviews of past ZEV credit transfers between manufacturers informed the 
decision to make this

[[Page 49641]]

simplifying assumption.\62\ CARB advised that for these manufacturers, 
the CAFE Model should still project that each manufacturer meet 
approximately 80% of their ZEV requirements with technology included in 
their own portfolio. Manufacturers that were observed to have generated 
many ZEV credits in the past or had announced major upcoming BEV 
initiatives were projected to meet 100% of their ZEV requirements on 
their own, without purchasing ZEV credits from other manufacturers.\63\
---------------------------------------------------------------------------

    \62\ See <a href="https://ww2.arb.ca.gov/our/work/programs/advanced-clean-cars-program/zev-program-zero-emission-vehicle-credit-balances">https://ww2.arb.ca.gov/our/work/programs/advanced-clean-cars-program/zev-program-zero-emission-vehicle-credit-balances</a> 
for past credit balances and transfer information.
    \63\ The following manufacturers were assumed to meet 100% ZEV 
compliance: Ford, General Motors, Hyundai, Kia, Jaguar Land Rover, 
and Volkswagen Automotive. Tesla was also assumed to meet 100% of 
its required standards, but the analyst team did not need to add 
additional ZEV substitutes to the baseline for this manufacturer.
---------------------------------------------------------------------------

    Third, DOT agreed that manufacturers would meet their ZEV credit 
requirements in 2025 though the production of BEVs. As discussed above, 
manufacturers may choose to build PHEVs or FCVs to earn some portion of 
their required ZEV credits. However, DOT projected that manufacturers 
would rely on BEVs to meet their credit requirements, based on reviews 
of press releases and industry news, as well as discussion with CARB. 
Since nearly all manufacturers have announced some plans to produce 
BEVs at a scale meaningful to future ZEV requirements, DOT agreed that 
this was a reasonable assumption.\64\ Furthermore, as CARB only allows 
intermediate-volume manufacturers to meet their ZEV credit requirements 
through the production of PHEVs, and the volume status of these few 
manufacturers could change over the years, assuming BEV production for 
ZEV compliance is the most straightforward path.
---------------------------------------------------------------------------

    \64\ See TSD Chapter 2.3 for a list of potential BEV programs 
recently announced by manufacturers.
---------------------------------------------------------------------------

    Fourth, to account for the new BEV programs announced by some 
manufacturers, DOT identified vehicles in the 2020 fleet that closely 
matched the upcoming BEVs, by regulatory class, market segment, and 
redesign schedule. DOT made an effort to distribute ZEV candidate 
vehicles by CAFE regulatory class (light truck, passenger car), by 
manufacturer, in a manner consistent with the 2020 manufacturer fleet 
mix. Since passenger car and light truck mixes by manufacturer could 
change in response to the CAFE policy alternative under consideration, 
this effort was deemed necessary in order to avoid redistributing the 
fleet mix in an unrealistic manner. However, there were some exceptions 
to this assumption, as some manufacturers are already closer to meeting 
their ZEV obligation through 2025 with BEVs currently produced, and 
some manufacturers underperform their compliance targets more so in one 
fleet than another. In these cases, DOT deviated from keeping the LT/PC 
mix of BEVs evenly distributed across the manufacturer's portfolio.\65\
---------------------------------------------------------------------------

    \65\ The GM light truck and passenger car distribution is one 
such example.
---------------------------------------------------------------------------

    DOT then identified future ZEV programs that could plausibly 
contribute towards the ZEV requirements for each manufacturer by 2025. 
To obtain this information, DOT examined various sources, including 
trade press releases, industry announcements, and investor reports. In 
many cases, these BEV programs are in addition to programs already in 
production.\66\ Some manufacturers have not yet released details of 
future electric vehicle programs at the time of writing, but have 
indicated goals of reaching certain percentages of electric vehicles in 
their portfolios by a specified year. In these cases, DOT reviewed the 
manufacturer's current fleet characteristics as well as the 
aspirational information in press releases and other news in order to 
make reasonable assumptions about the vehicle segment and range of 
those future BEVs. DOT may reassign some manufacturer's ZEV programs in 
the analysis fleet for the final rule based on stakeholder comments or 
other public information releases that occur in time for the final rule 
analysis.
---------------------------------------------------------------------------

    \66\ Examples of BEV programs already in production include the 
Nissan Leaf and the Chevrolet Bolt.
---------------------------------------------------------------------------

    Overall, analysts assumed that manufacturers would lean towards 
producing BEV300s rather than BEV200s, based on the information 
reviewed and an initial conversation with CARB.\67\ Phase-in caps were 
also considered, especially for BEV200, with the understanding that the 
CAFE Model will always pick BEV200 before BEV300 or BEV400, until the 
quantity of BEV200s is exhausted. See Section III.D.3.c) for details 
regarding BEV phase-in caps.
---------------------------------------------------------------------------

    \67\ BEV300s are 300-mile range battery-electric vehicles. See 
Section III.D.3.b) for further information regarding electrification 
fleet assignments.
---------------------------------------------------------------------------

    BEVs, especially BEVs with smaller battery packs and less range, 
are less likely to meet all the performance needs of traditional pickup 
truck owners today. However, new markets for BEVs may emerge, 
potentially in the form of electric delivery trucks and some light-duty 
electric truck applications in state and local government. The extent 
to which BEVs will be used in these and other new markets is difficult 
to project. DOT did identify certain trucks as upcoming BEVs for ZEV 
compliance, and these BEVs were expected to have higher ranges, due to 
the specific performance needs associated with these vehicles. Outside 
of the ZEV inputs described here, the CAFE Model does not handle the 
application of BEV technology with any special considerations as to 
whether the vehicle is a pickup truck or not. Comments from 
manufacturers are solicited on this issue.
    Finally, in order to simulate manufacturers' compliance with their 
particular ZEV credits target, 142 rows in the analysis fleet were 
identified as substitutes for future ZEV programs. As discussed above, 
the analysis fleet summarizes the roughly 13.6 million light-duty 
vehicles produced and sold in the United States in the 2020 model year 
with more than 3,500 rows, each reflecting information for one vehicle 
type observed. Each row includes the vehicle's nameplate and trim 
level, the sales volume, engine, transmission, drive configuration, 
regulatory class, projected redesign schedule, and fuel saving 
technologies, among other attributes.
    As the goal of the ZEV analysis is to simulate compliance with the 
ZEV program in the baseline, and the analysis fleet only contains 
vehicles produced during model year 2020, DOT identified existing 
models in the analysis fleet that shared certain characteristics with 
upcoming BEVs. DOT also focused on identifying substitute vehicles with 
redesign years similar to the future BEV's introduction year. The sales 
volumes of those existing models, as predicted for 2025, were then used 
to simulate production of the upcoming BEVs. DOT identified a 
combination of rows that would meet the ZEV target, could contribute 
productively towards CAFE program obligations (by manufacturer and by 
fleet), and would introduce BEVs in each manufacturer's portfolio in a 
way that reasonably aligned with projections and announcements. DOT 
tagged each of these rows with information in the Market Data file, 
instructing the CAFE Model to apply the specified BEV technology to the 
row at the first redesign year, regardless of the scenario or type of 
CAFE or GHG simulation.
    The CAFE Model does not optimize compliance with the ZEV mandate; 
it relies upon the inputs described in this section in order to 
estimate each

[[Page 49642]]

manufacturer's resulting ZEV credits. The resulting amount of ZEV 
credits earned by manufacturer for each model year can be found in the 
CAFE Model's Compliance file.
    Not all ZEV-qualifying vehicles in the U.S. earn ZEV credits, as 
they are not all sold in states that have adopted ZEV regulations. In 
order to reflect this in the CAFE Model, which only estimates sales 
volumes at the national level, the percentages calculated for each 
manufacturer are used to scale down the national-level volumes. 
Multiplying national-level ZEV sales volumes by these percentages 
ensures that only the ZEVs sold in Section 177 states count towards the 
ZEV credit targets of each manufacturer.\68\ See Section 5.8 of the 
CAFE Model Documentation for a detailed description of how the model 
applied these ZEV technologies and any changes made to the model's 
programming for the incorporation of the ZEV program into the baseline.
---------------------------------------------------------------------------

    \68\ The single exception to this assumption is Mazda, as Mazda 
has not yet produced any ZEV-qualifying vehicles at the time of 
writing. Thus, the percentage of ZEVs sold in Section 177 states 
cannot be calculated from existing data. However, Mazda has 
indicated its intention to produce ZEV-qualifying vehicles in the 
future, so DOT assumed that 100% of future ZEVs would be sold in 
Section 177 states for the purposes of estimating ZEV credits in the 
CAFE Model.
---------------------------------------------------------------------------

    As discussed above, DOT made an effort to distribute the newly 
identified ZEV candidates between CAFE regulatory classes (light truck 
and passenger car) in a manner consistent with the proportions seen in 
the 2020 analysis fleet, by manufacturer. As mentioned previously, 
there were a few exceptions to this assumption in cases where 
manufacturers' regulatory class distribution of current or planned ZEV 
programs clearly differed from their regulatory class distribution as a 
whole.
    In some instances, the regulatory distribution of flagged ZEV 
candidates leaned towards a higher portion of PCs. The reasoning behind 
this differs in each case, but there is an observed pattern in the 2020 
analysis fleet of fewer BEVs being light trucks, especially pickups. 
The 2020 analysis fleet contains no BEV pickups in the light truck 
segment. The slow emergence of electric pickups could be linked to the 
specific performance needs associated with pickup trucks. However, the 
market for BEVs may emerge in unexpected ways that are difficult to 
project. Examples of this include anticipated electric delivery trucks 
and light-duty electric trucks used by state and local governments. Due 
to these considerations, DOT tagged some trucks as BEVs for ZEV, and 
expected that these would generally be of higher ranges.
    TSD Chapter 2.3 includes more information about the process we use 
to simulate ZEV program compliance in this analysis.
4. Technology Effectiveness Values
    The next input we use to simulate manufacturers' decision-making 
processes for the year-by-year application of technologies to specific 
vehicles are estimates of how effective each technology would be at 
reducing fuel consumption. For this analysis, we use full-vehicle 
modeling and simulation to estimate the fuel economy improvements 
manufacturers could make to a fleet of vehicles, considering the 
vehicles' technical specifications and how combinations of technologies 
interact. Full-vehicle modeling and simulation uses physics-based 
models to predict how combinations of technologies perform as a full 
system under defined conditions. We use full vehicle simulations 
performed in Autonomie, a physics-based full-vehicle modeling and 
simulation software developed and maintained by the U.S. Department of 
Energy's Argonne National Laboratory.\69\
---------------------------------------------------------------------------

    \69\ Islam, E. S., A. Moawad, N. Kim, R. Vijayagopal, and A. 
Rousseau. A Detailed Vehicle Simulation Process to Support CAFE 
Standards for the MY 2024-2026 Analysis. ANL/ESD-21/9 [hereinafter 
Autonomie model documentation].
---------------------------------------------------------------------------

    A model is a mathematical representation of a system, and 
simulation is the behavior of that mathematical representation over 
time. In this analysis, the model is a mathematical representation of 
an entire vehicle,\70\ including its individual components such as the 
engine and transmission, overall vehicle characteristics such as mass 
and aerodynamic drag, and the environmental conditions, such as ambient 
temperature and barometric pressure. We simulate the model's behavior 
over test cycles, including the 2-cycle laboratory compliance tests (or 
2-cycle tests),\71\ to determine how the individual components 
interact.
---------------------------------------------------------------------------

    \70\ Each full vehicle model in this analysis is composed of 
sub-models, which is why the full vehicle model could also be 
referred to as a full system model, composed of sub-system models.
    \71\ EPA's compliance test cycles are used to measure the fuel 
economy of a vehicle. For readers unfamiliar with this process, it 
is like running a car on a treadmill following a program--or more 
specifically, two programs. The ``programs'' are the ``urban 
cycle,'' or Federal Test Procedure (abbreviated as ``FTP''), and the 
``highway cycle,'' or Highway Fuel Economy Test (abbreviated as 
``HFET'' or ``HWFET''), and they have not changed substantively 
since 1975. Each cycle is a designated speed trace (of vehicle speed 
versus time) that all certified vehicles must follow during testing. 
The FTP is meant roughly to simulate stop and go city driving, and 
the HFET is meant roughly to simulate steady flowing highway driving 
at about 50 mph.
---------------------------------------------------------------------------

    Using full-vehicle modeling and simulation to estimate technology 
efficiency improvements has two primary advantages over using single or 
limited point estimates. An analysis using single or limited point 
estimates may assume that, for example, one fuel economy-improving 
technology with an effectiveness value of 5 percent by itself and 
another technology with an effectiveness value of 10 percent by itself, 
when applied together achieve an additive improvement of 15 percent. 
Single point estimates generally do not provide accurate effectiveness 
values because they do not capture complex relationships among 
technologies. Technology effectiveness often differs significantly 
depending on the vehicle type (e.g., sedan versus pickup truck) and the 
way in which the technology interacts with other technologies on the 
vehicle, as different technologies may provide different incremental 
levels of fuel economy improvement if implemented alone or in 
combination with other technologies. Any oversimplification of these 
complex interactions leads to less accurate and often overestimated 
effectiveness estimates.
    In addition, because manufacturers often implement several fuel-
saving technologies simultaneously when redesigning a vehicle, it is 
difficult to isolate the effect of individual technologies using 
laboratory measurement of production vehicles alone. Modeling and 
simulation offer the opportunity to isolate the effects of individual 
technologies by using a single or small number of baseline vehicle 
configurations and incrementally adding technologies to those baseline 
configurations. This provides a consistent reference point for the 
incremental effectiveness estimates for each technology and for 
combinations of technologies for each vehicle type. Vehicle modeling 
also reduces the potential for overcounting or undercounting technology 
effectiveness.
    An important feature of this analysis is that the incremental 
effectiveness of each technology and combinations of technologies 
should be accurate and relative to a consistent baseline vehicle. For 
this analysis, the baseline absolute fuel economy value for each 
vehicle in the analysis fleet is based on CAFE compliance data for each 
make and model.\72\ The absolute fuel economy values of the full 
vehicle simulations are

[[Page 49643]]

used only to determine incremental effectiveness and are never used 
directly to assign an absolute fuel economy value to any vehicle model 
or configuration. For subsequent technology changes, we apply the 
incremental effectiveness values of one or more technologies to the 
baseline fuel economy value to determine the absolute fuel economy 
achieved for applying the technology change.
---------------------------------------------------------------------------

    \72\ See Section III.C.2 for further discussion of CAFE 
compliance data in the Market Data file.
---------------------------------------------------------------------------

    As an example, if a Ford F-150 2-wheel drive crew cab and short bed 
in the analysis fleet has a fuel economy value of 30 mpg for CAFE 
compliance, 30 mpg will be considered the reference absolute fuel 
economy value. A similar full vehicle model node in the Autonomie 
simulation may begin with an average fuel economy value of 32 mpg, and 
with incremental addition of a specific technology X its fuel economy 
improves to 35 mpg, a 9.3 percent improvement. In this example, the 
incremental fuel economy improvement (9.3 percent) from technology X 
would be applied to the F-150's 30 mpg absolute value.
    We determine the incremental effectiveness of technologies as 
applied to the thousands of unique vehicle and technology combinations 
in the analysis fleet. Although, as mentioned above, full-vehicle 
modeling and simulation reduces the work and time required to assess 
the impact of moving a vehicle from one technology state to another, it 
would be impractical--if not impossible--to build a unique vehicle 
model for every individual vehicle in the analysis fleet. Therefore, as 
discussed in the following sections, the Autonomie analysis relies on 
ten vehicle technology class models that are representative of large 
portions of the analysis fleet vehicles. The vehicle technology classes 
ensure that key vehicle characteristics are reasonably represented in 
the full vehicle models. The next sections discuss the details of the 
technology effectiveness analysis input specifications and assumptions. 
NHTSA seeks comment on the following discussion.
(a) Full Vehicle Modeling and Simulation
    As discussed above, for this analysis we use Argonne's full vehicle 
modeling tool, Autonomie, to build vehicle models with different 
technology combinations and simulate the performance of those models 
over regulatory test cycles. The difference in the simulated 
performance between full vehicle models, with differing technology 
combination, is used to determine effectiveness values. We consider 
over 50 individual technologies as inputs to the Autonomie 
modeling.\73\ These inputs consist of engine technologies, transmission 
technologies, powertrain electrification, lightweighting, aerodynamic 
improvements, and tire rolling resistance improvements. Section III.D 
broadly discusses each of the technology groupings definitions, inputs, 
and assumptions. A deeper discussion of the Autonomie modeled 
subsystems, and how inputs feed the sub models resulting in outputs, is 
contained in the Autonomie model documentation that accompanies this 
analysis. The 50 individual technologies, when considered with the ten 
vehicle technology classes, result in over 1.1 million individual 
vehicle technology combination models. For additional discussion on the 
full vehicle modeling used in this analysis see TSD Chapter 2.
---------------------------------------------------------------------------

    \73\ See Autonomie model documentation; ANL--All 
Assumptions_Summary_NPRM_022021.xlsx; ANL--Data Dictionary_January 
2021.xlsx.
---------------------------------------------------------------------------

    While Argonne built full-vehicle models and ran simulations for 
many combinations of technologies, it did not simulate literally every 
single vehicle model/configuration in the analysis fleet. Not only 
would it be impractical to assemble the requisite detailed information 
specific to each vehicle/model configuration, much of which would 
likely only be provided on a confidential basis, doing so would 
increase the scale of the simulation effort by orders of magnitude. 
Instead, Argonne simulated ten different vehicle types, corresponding 
to the five ``technology classes'' generally used in CAFE analysis over 
the past several rulemakings, each with two performance levels and 
corresponding vehicle technical specifications (e.g., small car, small 
performance car, pickup truck, performance pickup truck, etc.).
    Technology classes are a means of specifying common technology 
input assumptions for vehicles that share similar characteristics. 
Because each vehicle technology class has unique characteristics, the 
effectiveness of technologies and combinations of technologies is 
different for each technology class. Conducting Autonomie simulations 
uniquely for each technology class provides a specific set of 
simulations and effectiveness data for each technology class. In this 
analysis the technology classes are compact cars, midsize cars, small 
SUVs, large SUVs, and pickup trucks. In addition, for each vehicle 
class there are two levels of performance attributes (for a total of 10 
technology classes). The high performance and low performance vehicles 
classifications allow for better diversity in estimating technology 
effectiveness across the fleet.
    For additional discussion on the development of the vehicle 
technology classes used in this analysis and the attributes used to 
characterize each vehicle technology class, see TSD Chapter 2.4 and the 
Autonomie model documentation.
    Before any simulation is initiated in Autonomie, Argonne must 
``build'' a vehicle by assigning reference technologies and initial 
attributes to the components of the vehicle model representing each 
technology class. The reference technologies are baseline technologies 
that represent the first step on each technology pathway used in the 
analysis. For example, a compact car is built by assigning it a 
baseline engine (DOHC, VVT, port fuel injection (PFI)), a baseline 
transmission (AT5), a baseline level of aerodynamic improvement 
(AERO0), a baseline level of rolling resistance improvement (ROLL0), a 
baseline level of mass reduction technology (MR0), and corresponding 
attributes from the Argonne vehicle assumptions database like 
individual component weights. A baseline vehicle will have a unique 
starting point for the simulation and a unique set of assigned inputs 
and attributes, based on its technology class. Argonne collected over a 
hundred baseline vehicle attributes to build the baseline vehicle for 
each technology class. In addition, to account for the weight of 
different engine sizes, like 4-cylinder versus 8-cylinder or 
turbocharged versus naturally aspirated engines, Argonne developed a 
relationship curve between peak power and engine weight based on the 
A2Mac1 benchmarking data. Argonne uses the developed relationship to 
estimate mass for all engines. For additional discussion on the 
development and optimization of the baseline vehicle models and the 
baseline attributes used in this analysis see TSD Chapter 2.4 and the 
Autonomie model documentation.
    The next step in the process is to run a powertrain sizing 
algorithm that ensures the built vehicle meets or exceeds defined 
performance metrics, including low-speed acceleration (time required to 
accelerate from 0-60 mph), high-speed passing acceleration (time 
required to accelerate from 50-80 mph), gradeability (the ability of 
the vehicle to maintain constant 65 miles per hour speed on a six 
percent upgrade), and towing capacity. Together, these performance 
criteria are widely used by the automotive industry as metrics to 
quantify vehicle performance attributes

[[Page 49644]]

that consumers observe and that are important for vehicle utility and 
customer satisfaction.
    As with conventional vehicle models, electrified vehicle models 
were also built from the ground up. For MY 2020, the U.S. market has an 
expanded number of available hybrid and electric vehicle models. To 
capture improvements for electrified vehicles for this analysis, DOT 
applied a mass regression analysis process that considers electric 
motor weight versus electric motor power (similar to the regression 
analysis for internal combustion engine weights) for vehicle models 
that have adopted electric motors. Benchmarking data for hybrid and 
electric vehicles from the A2Mac1 database were analyzed to develop a 
regression curve of electric motor peak power versus electric motor 
weight.\74\
---------------------------------------------------------------------------

    \74\ See Autonomie model documentation, Chapter 5.2.10 Electric 
Machines System Weight.
---------------------------------------------------------------------------

    We maintain performance neutrality in the full vehicle simulations 
by resizing engines, electric machines, and hybrid electric vehicle 
battery packs at specific incremental technology steps. To address 
product complexity and economies of scale, engine resizing is limited 
to specific incremental technology changes that would typically be 
associated with a major vehicle or engine redesign. This is intended to 
reflect manufacturers' comments to DOT on how they consider engine 
resizing and product complexity, and DOT's observations on industry 
product complexity. A detailed discussion on powertrain sizing can be 
found in TSD Chapter 2.4 and in the Autonomie model documentation.
    After all vehicle class and technology combination models have been 
built, Autonomie simulates the vehicles' performance on test cycles to 
calculate the effectiveness improvement of adding fuel-economy-
improving technologies to the vehicle. Simulating vehicles' performance 
using tests and procedures specified by Federal law and regulations 
minimizes the potential variation in determining technology 
effectiveness.
    For vehicles with conventional powertrains and micro hybrids, 
Autonomie simulates the vehicles per EPA 2-cycle test procedures and 
guidelines.\75\ For mild and full hybrid electric vehicles and FCVs, 
Autonomie simulates the vehicles using the same EPA 2-cycle test 
procedure and guidelines, and the drive cycles are repeated until the 
initial and final state of charge are within a SAE J1711 tolerance. For 
PHEVs, Autonomie simulates vehicles per similar procedures and 
guidelines as prescribed in SAE J1711.\76\ For BEVs Autonomie simulates 
vehicles per similar procedures and guidelines as prescribed in SAE 
J1634.\77\
---------------------------------------------------------------------------

    \75\ 40 CFR part 600.
    \76\ PHEV testing is broken into several phases based on SAE 
J1711: Charge-sustaining on the city cycle and HWFET cycle, and 
charge-depleting on the city and HWFET cycles.
    \77\ SAE J1634. ``Battery Electric Vehicle Energy Consumption 
and Range Test Procedure.'' July 12, 2017.
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(b) Performance Neutrality
    The purpose of the CAFE analysis is to examine the impact of 
technology application that can improve fuel economy. When the fuel 
economy-improving technology is applied, often the manufacturer must 
choose how the technology will affect the vehicle. The advantages of 
the new technology can either be completely applied to improving fuel 
economy or be used to increase vehicle performance while maintaining 
the existing fuel economy, or some mix of the two effects. 
Historically, vehicle performance has improved over the years as more 
technology is applied to the fleet. The average horsepower is the 
highest that it has ever been; all vehicle types have improved 
horsepower by at least 42 percent compared to the 1978 model year, and 
pickup trucks have improved by 48 percent.\78\ Fuel economy has also 
improved, but the horsepower and acceleration trends show that not 100 
percent of technological improvements have been applied to fuel 
savings. While future trends are uncertain, the past trends suggest 
vehicle performance is unlikely to decrease, as it seems reasonable to 
assume that customers will, at a minimum, demand vehicles that offer 
the same utility as today's fleet.
---------------------------------------------------------------------------

    \78\ ``The 2020 EPA Automotive Trends Report, Greenhouse Gas 
Emissions, Fuel Economy, and Technology since 1975,'' EPA-420-R-21-
003, January 2021 [hereinafter 2020 EPA Automotive Trends Report].
---------------------------------------------------------------------------

    For this rulemaking analysis, DOT analyzed technology pathways 
manufacturers could use for compliance that attempt to maintain vehicle 
attributes, utility, and performance. Using this approach allows DOT to 
assess the costs and benefits of potential standards under a scenario 
where consumers continue to get the similar vehicle attributes and 
features, other than changes in fuel economy. The purpose of 
constraining vehicle attributes is to simplify the analysis and reduce 
variance in other attributes that consumers may value across the 
analyzed regulatory alternatives. This allows for a streamlined 
accounting of costs and benefits by not requiring the values of other 
vehicle attributes that trade off with fuel economy.
    To confirm minimal differences in performance metrics across 
regulatory alternatives, DOT analyzed the sales-weighted average 0-60 
mph acceleration performance of the entire simulated vehicle fleet for 
MYs 2020 and 2029. The analysis compared performance under the baseline 
standards and preferred alternative. This analysis identified that the 
analysis fleet under no action standards in MY 2029 had a 0.77 percent 
worse 0-60 mph acceleration time than under the preferred alternative, 
indicating there is minimal difference in performance between the 
alternatives. This assessment shows that for this analysis, the 
performance difference is minimal across regulatory alternatives and 
across the simulated model years, which allows for fair, direct 
comparison among the alternatives. Further details about this 
assessment can be found in TSD Chapter 2.4.5.
(c) Implementation in the CAFE Model
    The CAFE Model uses two elements of information from the large 
amount of data generated by the Autonomie simulation runs: Battery 
costs, and fuel consumption on the city and highway cycles. DOT 
combines the fuel economy information from the two cycles to produce a 
composite fuel economy for each vehicle, and for each fuel used in dual 
fuel vehicles. The fuel economy information for each simulation run is 
converted into a single value for use in the CAFE Model.
    In addition to the technologies in the Autonomie simulation, the 
CAFE Model also incorporated a handful of technologies not explicitly 
simulated in Autonomie. These technologies' performance either could 
not be captured on the 2-cycle test, or there was no robust data usable 
as an input for full-vehicle modeling and simulation. The specific 
technologies are discussed in the individual technology sections below 
and in TSD Chapter 3. To calculate fuel economy improvements 
attributable to these additional technologies, estimates of fuel 
consumption improvement factors were developed and scale 
multiplicatively when applied together. See TSD Chapter 3 for a 
complete discussion on how these factors were developed. The Autonomie-
simulated results and additional technologies are combined, forming a 
single dataset used by the CAFE Model.
    Each line in the CAFE Model dataset represents a unique combination 
of technologies. DOT organizes the records using a unique technology 
state vector,

[[Page 49645]]

or technology key (tech key), that describes the technology content 
associated with each unique record. The modeled 2-cycle fuel economy 
(miles per gallon) of each combination is converted into fuel 
consumption (gallons per mile) and then normalized relative to a 
baseline tech key. The improvement factors used by the model are a 
given combination's fuel consumption improvement relative to the 
baseline tech key in its technology class.
    The tech key format was developed by recognizing that most of the 
technology pathways are unrelated and are only logically linked to 
designate the direction in which technologies are allowed to progress. 
As a result, it is possible to condense the paths into groups based on 
the specific technology. These groups are used to define the technology 
vector, or tech key. The following technology groups defined the tech 
key: Engine cam configuration (CONFIG), VVT engine technology (VVT), 
VVL engine technology (VVL), SGDI engine technology (SGDI), DEAC engine 
technology (DEAC), non-basic engine technologies (ADVENG), transmission 
technologies (TRANS), electrification and hybridization (ELEC), low 
rolling resistance tires (ROLL), aerodynamic improvements (AERO), mass 
reduction levels (MR), EFR engine technology (EFR), electric accessory 
improvement technologies (ELECACC), LDB technology (LDB), and SAX 
technology (SAX). This summarizes to a tech key with the following 
fields: CONFIG; VVT; VVL; SGDI; DEAC; ADVENG; TRANS; ELEC; ROLL; AERO; 
MR; EFR; ELECACC; LDB; SAX. It should be noted that some of the fields 
may be blank for some tech key combinations. These fields will be left 
visible for the examples below, but blank fields may be omitted from 
tech keys shown elsewhere in the documentation.
    As an example, a technology state vector describing a vehicle with 
a SOHC engine, variable valve timing (only), a 6-speed automatic 
transmission, a belt-integrated starter generator, rolling resistance 
(level 1), aerodynamic improvements (level 2), mass reduction (level 
1), electric power steering, and low drag brakes, would be specified as 
``SOHC; VVT; ; ; ; ; AT6; BISG; ROLL10; AERO20; MR1; ; EPS; LDB ; .'' 
\79\
---------------------------------------------------------------------------

    \79\ In the example tech key, the series of semicolons between 
VVT and AT6 correspond to the engine technologies which are not 
included as part of the combination, while the gap between MR1 and 
EPS corresponds to EFR and the omitted technology after LDB is SAX. 
The extra semicolons for omitted technologies are preserved in this 
example for clarity and emphasis and will not be included in future 
examples.
---------------------------------------------------------------------------

    Once a vehicle is assigned (or mapped) to an appropriate tech key, 
adding a new technology to the vehicle simply represents progress from 
a previous tech key to a new tech key. The previous tech key refers to 
the technologies that are currently in use on a vehicle. The new tech 
key is determined, in the simulation, by adding a new technology to the 
combination represented by the previous state vector while 
simultaneously removing any technologies that are superseded by the 
newly added one.
    For example, start with a vehicle with the tech key: SOHC; VVT; 
AT6; BISG; ROLL10; AERO20; MR1; EPS; LDB. Assume the simulation is 
evaluating PHEV20 as a candidate technology for application on this 
vehicle. The new tech key for this vehicle is computed by removing 
SOHC, VVT, AT6, and BISG technologies from the previous state 
vector,\80\ and adding PHEV20, resulting a tech key that looks like 
this: PHEV20; ROLL10; AERO20; MR1; EPS; LDB.
---------------------------------------------------------------------------

    \80\ For more discussion of how the CAFE Model handles 
technology supersession, see S4.5 of the CAFE Model Documentation.
---------------------------------------------------------------------------

    From here, the simulation obtains a fuel economy improvement factor 
for the new combination of technologies and applies that factor to the 
fuel economy of a vehicle in the analysis fleet. The resulting 
improvement is applied to the original compliance fuel economy value 
for a discrete vehicle in the MY 2020 analysis fleet.
5. Defining Technology Adoption in the Rulemaking Timeframe
    As discussed in Section III.C.2, starting with a fixed analysis 
fleet (for this analysis, the model year 2020 fleet indicated in 
manufacturers' early CAFE compliance data), the CAFE Model estimates 
ways each manufacturer could potentially apply specific fuel-saving 
technologies to specific vehicle model/configurations in response to, 
among other things (such as fuel prices), CAFE standards, 
CO<INF>2</INF> standards, commitments some manufacturers have made to 
CARB's ``Framework Agreement'', and ZEV mandates imposed by California 
and several other States. The CAFE Model follows a year-by-year 
approach to simulating manufacturers' potential decisions to apply 
technology, accounting for multiyear planning within the context of 
estimated schedules for future vehicle redesigns and refreshes during 
which significant technology changes may most practicably be 
implemented.
    The modeled technology adoption for each manufacturer under each 
regulatory alternative depends on this representation of multiyear 
planning, and on a range of other factors represented by other model 
characteristics and inputs, such as the logical progression of 
technologies defined by the model's technology pathways; the 
technologies already present in the analysis fleet; inputs directing 
the model to ``skip'' specific technologies for specific vehicle model/
configurations in the analysis fleet (e.g., because secondary axle 
disconnect cannot be applied to 2-wheel-drive vehicles, and because 
manufacturers already heavily invested in engine turbocharging and 
downsizing are unlikely to abandon this approach in favor of using high 
compression ratios); inputs defining the sharing of engines, 
transmissions, and vehicle platforms in the analysis fleet; the model's 
logical approach to preserving this sharing; inputs defining each 
regulatory alternative's specific requirements; inputs defining 
expected future fuel prices, annual mileage accumulation, and valuation 
of avoided fuel consumption; and inputs defining the estimated efficacy 
and future cost (accounting for projected future ``learning'' effects) 
of included technologies; inputs controlling the maximum pace the 
simulation is to ``phase in'' each technology; and inputs further 
defining the availability of each technology to specific technology 
classes.
    Two of these inputs--the ``phase-in cap'' and the ``phase-in start 
year''--apply to the manufacturer's entire estimated production and, 
for each technology, define a share of production in each model year 
that, once exceeded, will stop the model from further applying that 
technology to that manufacturer's fleet in that model year. The 
influence of these inputs varies with regulatory stringency and other 
model inputs. For example, setting the inputs to allow immediate 100% 
penetration of a technology will not guarantee any application of the 
technology if stringency increases are low and the technology is not at 
all cost effective. Also, even if these are set to allow only very slow 
adoption of a technology, other model aspects and inputs may 
nevertheless force more rapid application than these inputs, alone, 
would suggest (e.g., because an engine technology propagates quickly 
due to sharing across multiple vehicles, or because BEV application 
must increase quickly in response to ZEV requirements). For this 
analysis, nearly

[[Page 49646]]

all of these inputs are set at levels that do not limit the simulation 
at all.
    As discussed below, for the most advanced engines (advanced 
cylinder deactivation, variable compression ratio, variable 
turbocharger geometry, and turbocharging with cylinder deactivation), 
DOT has specified phase-in caps and phase-in start years that limit the 
pace at which the analysis shows the technology being adopted in the 
rulemaking timeframe. For example, this analysis applies a 34% phase-in 
cap and MY 2019 phase-in start year for advanced cylinder deactivation 
(ADEAC), meaning that in MY 2021 (using a MY 2020 fleet, the analysis 
begins simulating further technology application in MY 2021), the model 
will stop adding ADEAC to a manufacturer's MY 2021 fleet once ADEAC 
reaches more than 68% penetration, because 34% x (2021-2019) = 34% x 2 
= 68%.
    This analysis also applies phase-in caps and corresponding start 
years to prevent the simulation from showing inconceivable rates of 
applying battery-electric vehicles (BEVs), such as showing that a 
manufacturer producing very few BEVs in MY 2020 could plausibly replace 
every product with a 300- or 400-mile BEV by MY 2025. Also, as 
discussed in Section III.D.4, this analysis applies phase-in caps and 
corresponding start years intended to ensure that the simulation's 
plausible application of the highest included levels of mass reduction 
(20% and 28.2% reductions of vehicle ``glider'' weight) do not, for 
example, outpace plausible supply of raw materials and development of 
entirely new manufacturing facilities.
    These model logical structures and inputs act together to produce 
estimates of ways each manufacturer could potentially shift to new 
fuel-saving technologies over time, reflecting some measure of 
protection against rates of change not reflected in, for example, 
technology cost inputs. This does not mean that every modeled solution 
would necessarily be economically practicable. Using technology 
adoption features like phase-in caps and phase-in start years is one 
mechanism that can be used so that the analysis better represents the 
potential costs and benefits of technology application in the 
rulemaking timeframe.
6. Technology Costs
    DOT estimates present and future costs for fuel-saving technologies 
taking into consideration the type of vehicle, or type of engine if 
technology costs vary by application. These cost estimates are based on 
three main inputs. First, direct manufacturing costs (DMCs), or the 
component and labor costs of producing and assembling the physical 
parts and systems, are estimated assuming high volume production. DMCs 
generally do not include the indirect costs of tools, capital 
equipment, financing costs, engineering, sales, administrative support 
or return on investment. DOT accounts for these indirect costs via a 
scalar markup of direct manufacturing costs (the retail price 
equivalent, or RPE). Finally, costs for technologies may change over 
time as industry streamlines design and manufacturing processes. To 
reflect this, DOT estimates potential cost improvements with learning 
effects (LE). The retail cost of equipment in any future year is 
estimated to be equal to the product of the DMC, RPE, and LE. 
Considering the retail cost of equipment, instead of merely direct 
manufacturing costs, is important to account for the real-world price 
effects of a technology, as well as market realities. Absent a 
Government mandate, motor vehicle manufacturers will not undertake 
expensive development and production efforts to implement technologies 
without realistic prospects of consumers being willing to pay enough 
for such technology to allow for the manufacturers to recover their 
investment.
(a) Direct Manufacturing Costs
    Direct manufacturing costs (DMCs) are the component and assembly 
costs of the physical parts and systems that make up a complete 
vehicle. The analysis used agency-sponsored tear-down studies of 
vehicles and parts to estimate the DMCs of individual technologies, in 
addition to independent tear-down studies, other publications, and 
confidential business information. In the simplest cases, the agency-
sponsored studies produced results that confirmed third-party industry 
estimates and aligned with confidential information provided by 
manufacturers and suppliers. In cases with a large difference between 
the tear-down study results and credible independent sources, DOT 
scrutinized the study assumptions, and sometimes revised or updated the 
analysis accordingly.
    Due to the variety of technologies and their applications, and the 
cost and time required to conduct detailed tear-down analyses, the 
agency did not sponsor teardown studies for every technology. In 
addition, some fuel-saving technologies were considered that are pre-
production or are sold in very small pilot volumes. For those 
technologies, DOT could not conduct a tear-down study to assess costs 
because the product is not yet in the marketplace for evaluation. In 
these cases, DOT relied upon third-party estimates and confidential 
information from suppliers and manufacturers; however, there are some 
common pitfalls with relying on confidential business information to 
estimate costs. The agency and the source may have had incongruent or 
incompatible definitions of ``baseline.'' The source may have provided 
DMCs at a date many years in the future, and assumed very high 
production volumes, important caveats to consider for agency analysis. 
In addition, a source, under no contractual obligation to DOT, may 
provide incomplete and/or misleading information. In other cases, 
intellectual property considerations and strategic business 
partnerships may have contributed to a manufacturer's cost information 
and could be difficult to account for in the CAFE Model as not all 
manufacturers may have access to proprietary technologies at stated 
costs. The agency carefully evaluates new information in light of these 
common pitfalls, especially regarding emerging technologies.
    W

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