Improvements for Heavy-Duty Engine and Vehicle Test Procedures

Improvements for Heavy-Duty Engine and Vehicle Test Procedures

Improvements for Heavy-Duty Engine and Vehicle Test Procedures

Jane Nishida
Environmental Protection Agency
29 June 2021

[Federal Register Volume 86, Number 122 (Tuesday, June 29, 2021)]
[Proposed Rules]
[Pages 34189-34194]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2021-05305]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Parts 1036 and 1037

[EPA-HQ-OAR-2019-0307; FRL-10018-51-OAR]

Improvements for Heavy-Duty Engine and Vehicle Test Procedures

AGENCY: Environmental Protection Agency (EPA).

ACTION: Notice of proposed rulemaking.

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SUMMARY: This notice of proposed rulemaking includes corrections,
clarifications, additional flexibilities, and adjustment factors to
improve the Greenhouse gas Emissions Model (GEM) compliance tool for
heavy-duty vehicles while more closely matching the outputs produced by
the original GEM version 3.0 that was used to establish the
CO2 standards for Model Years 2021 and later in the 2016
Heavy-duty Phase 2 final rule. This document supplements the proposed
rule published on May 12, 2020, which included a larger set of proposed
revisions to modify and improve GEM. Most of the proposed revisions
from that notice of proposed rulemaking are addressed in a final
rulemaking published elsewhere in the Final Rules section of this issue
of the Federal Register. Given the nature of this proposal, there will
be neither

[[Page 34190]]

significant environmental impacts nor significant economic impacts for
any sector.

DATES:
Comments: Comments must be received on or before August 30, 2021.
Public Hearing: If anyone contacts us requesting a public hearing
on or before July 6, 2021, we will hold an online hearing at 10 a.m.
Eastern Standard Time on July 14, 2021.

ADDRESSES:
Comments: Submit your comments, identified by Docket ID No. EPA-HQ-
OAR-2019-0307, at http://www.regulations.gov. For detailed instructions
on sending comments and additional information on the rulemaking
process, see the ``Public Participation'' section of this document.
Docket: EPA has established a docket for this action under Docket
ID No. EPA-HQ-OAR-2019-0307. Publicly available docket materials are
available either electronically at http://www.regulations.gov or in
hard copy at Air and Radiation Docket and Information Center, EPA
Docket Center, EPA/DC, EPA WJC West Building, 1301 Constitution Ave.
NW, Room 3334, Washington, DC. Out of an abundance of caution for
members of the public and our staff, the EPA Docket Center and Reading
Room was closed to public visitors on March 31, 2020, to reduce the
risk of transmitting COVID-19. Our Docket Center staff will continue to
provide remote customer service via email, phone, and webform. We
encourage the public to submit comments via https://www.regulations.gov
or email, as there is a temporary suspension of mail delivery to EPA,
and no hand deliveries are currently accepted. For further information
on EPA Docket Center services and the current status, please visit us
online at https://www.epa.gov/dockets.
Public Hearing: Individuals are invited to notify EPA of interest
in a public hearing; see FOR FURTHER INFORMATION CONTACT.
Public Participation: Comments: All submissions received must
include the Docket ID No. EPA-HQ-OAR-2019-0307 for this rulemaking.
Follow the online instructions for submitting comments. Once submitted,
comments received may be posted without change to https://www.regulations.gov/, including any personal information provided, and
cannot be edited or removed from Regulations.gov. The EPA may publish
any comment received to its public docket. Do not submit electronically
any information you consider to be Confidential Business Information
(CBI) or other information whose disclosure is restricted by statute.
Multimedia submissions (audio, video, etc.) must be accompanied by a
written comment. The written comment is considered the official comment
and should include discussion of all points you wish to make. The EPA
will generally not consider comments or comment contents located
outside of the primary submission (i.e., on the web, cloud, or other
file sharing system). For additional submission methods, the full EPA
public comment policy, information about CBI or multimedia submissions,
and general guidance on making effective comments, please visit http://www2.epa.gov/dockets/commenting-epa-dockets.
Out of an abundance of caution for members of the public and our
staff, the EPA Docket Center and Reading Room was closed to public
visitors on March 31, 2020, to reduce the risk of transmitting COVID-
19. Our Docket Center staff will continue to provide remote customer
service via email, phone, and webform. We encourage the public to
submit comments via https://www.regulations.gov or email, as there is a
temporary suspension of mail delivery to EPA, and no hand deliveries
are currently accepted. For further information on EPA Docket Center
services and the current status, please visit us online at https://www.epa.gov/.
EPA continues to carefully and continuously monitor information
from the Centers for Disease Control and Prevention, local area health
departments, and our Federal partners so we can respond rapidly as
conditions change regarding COVID-19.
Docket: All documents in the docket are listed on the
www.regulations.gov website. Although listed in the index, some
information is not publicly available, e.g., CBI or other information
whose disclosure is restricted by statute. Certain other material, such
as copyrighted material, is not placed on the internet and will be
publicly available only in hard copy form through the EPA Docket Center
at the location listed in the ADDRESSES section of this document.
Public Hearing: If we hold a public hearing, we will announce
detailed information about the hearing on our website https://www.epa.gov/regulations-emissions-vehicles-and-engines/supplemental-rule-improvements-heavy-duty-engine-and. Send requests for a hearing
and questions about the status of a hearing to the contact identified
in FOR FURTHER INFORMATION CONTACT.

FOR FURTHER INFORMATION CONTACT: Amy Kopin, Office of Transportation
and Air Quality, Assessment and Standards Division, Environmental
Protection Agency, 2000 Traverwood Drive, Ann Arbor, MI 48105;
telephone number: (734) 214-4173; email address: kopin.amy@epa.gov.

SUPPLEMENTARY INFORMATION:

Table of Contents

I. General Information
II. Greenhouse Gas Emissions Model (GEM) Background
III. Proposed Updates to GEM
IV. Statutory Authority and Executive Order Reviews

I. General Information

Does this action apply to me?

This action relates to companies that manufacture or sell new
heavy-duty engines and vehicles as defined under EPA's CAA
regulations.\1\ Regulated categories and entities include the
following:
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\1\ ``Heavy-duty engine'' and ``heavy-duty vehicle'' are defined
in 40 CFR 1037.801.

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Examples of
NAICS codes \A\ NAICS titles potentially
regulated entities
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333618, 336111, 336112, 336120, Other Engine Motor vehicle
336211, 336999. Equipment manufacturers and
Manufacturing, engine
Automobile manufacturers.
Manufacturing,
Light Truck and
Utility Vehicle
Manufacturing,
Heavy Duty Truck
Manufacturing,
Motor Vehicle
Body
Manufacturing,
All Other
Transportation
Equipment
Manufacturing.
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\A\ North American Industry Classification System (NAICS).

[[Page 34191]]

This list is not intended to be exhaustive, but rather provides a
guide for readers regarding entities likely to be regulated by this
action. If you have questions regarding the applicability of this
action to a particular entity, consult the person listed in the FOR
FURTHER INFORMATION CONTACT section.

What action is the Agency taking?

This action proposes to amend the regulations that implement our
air pollutant emission standards for heavy-duty engines and vehicles.
The proposed amendments in this notice of proposed rulemaking include
corrections, clarifications, additional flexibilities, and adjustment
factors to the Greenhouse gas Emissions Model (GEM) compliance tool for
heavy-duty vehicles. These amendments would modify the existing test
procedure for heavy-duty highway engines and vehicles and apply to the
measurement of CO2 emissions. EPA published a proposed rule
on May 12, 2020 (85 FR 28153) (``Technical Amendments proposed rule'').
EPA is issuing a final rulemaking (``Technical Amendments final rule'')
relating to most revisions proposed in the Technical Amendments
proposed rule, published in the Final Rules section of this issue of
the Federal Register, titled ``Improvements for Heavy-Duty Engine and
Vehicle Test Procedures, and other technical amendments,'' docket
number EPA-HQ-OAR-2019-0307; FRL-10018-52-OAR.
This action supplements the Technical Amendments proposed rule for
only certain specific aspects of revising GEM by proposing several
amendments to the model, after consideration of comments solicited and
received on the Technical Amendments proposed rule, including a
proposed revision to address concerns raised regarding potential
stringency impacts that may result from changes to GEM.

What are the incremental costs and benefits of this action?

This action is limited in scope and does not have significant
economic or environmental impacts. EPA has therefore not estimated the
potential costs or benefits of this notice of proposed rulemaking.

II. Greenhouse Gas Emissions Model (GEM) Background

GEM is a computer application that estimates the greenhouse gas
(GHG) emissions and fuel efficiency performance of specific aspects of
heavy-duty vehicles. GEM uses several vehicle-specific inputs, such as
engine fuel maps, aerodynamic drag coefficients, and vehicle weight
ratings, to simulate vehicle and engine operation and model the amount
of CO2 emitted over multiple duty cycles for tractors and
vocational vehicles. The resulting CO2 values over these
cycles are weighted by GEM to provide a composite GEM score. GEM
version 3.0 was used to set standards in the Greenhouse Gas Emissions
and Fuel Efficiency Standards for Medium- and Heavy-Duty Engines and
Vehicles-Phase 2 (``Phase 2'') rulemaking (81 FR 73478). For purposes
of determining compliance, composite GEM scores are compared to the
applicable Phase 2 vehicle standard.
In the Technical Amendments proposed rule, we proposed several
amendments to GEM 3.0, including corrections, clarifications, and
additional flexibilities in a revised version of the model, GEM 3.5 (85
FR 28145). EPA also requested comment on whether any differences in GEM
output values resulting from changes to the model would impact the
effective stringency of the program and, if so, whether EPA should
revise the GEM model itself or address such impacts via regulations
(see 85 FR 28145).
Comments received in response to the NRPM supported most of the
proposed updates to GEM and requested additional revisions to further
improve the model.\2\ The California Air Resources Board (CARB)
provided comment on this topic, stating the importance of GEM results
being consistent with the current program standards to avoid affecting
program stringency. CARB recommended that EPA revise GEM in order to
ensure stringency is maintained.\3\
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\2\ See ``Improvements for Heavy-Duty Engine and Vehicle Test
Procedures, and other Technical Amendments Response to Comments'',
Publication Number: EPA-420-R-20-026, December 2020. Chapter 2 of
the Response to Comments provides additional details on the
amendments, clarifications requested by commenters, and our
responses to most of the comments to the NPRM.
\3\ California Air Resources Board, Docket number EPA-HQ-OAR-
2019-0207-0030.
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After considering the comments received, EPA applied further
potential changes to GEM 3.5 and released a new development version of
GEM, GEM 3.7, to the public for download and review by stakeholders to
evaluate and assess the performance of this revised model. GEM 3.7
incorporated some corrections and improvements relative to the proposed
version GEM 3.5, as noted in the corresponding memorandum in the
rulemaking docket.\4\
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\4\ Nelson, Brian. Memorandum to Docket EPA-HQ-OAR-2019-0307.
``Development version of GEM and adjustment factors''. October 23,
2020. Docket number EPA-HQ-OAR-2019-0307-0083. Also available
online: https://www3.epa.gov/otaq/gem-p2v3.7-release-memo-2020-10-23.pdf.
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While evaluating GEM 3.7, we found differences in the output values
for some tractor and vocational vehicles compared to the output values
from GEM 3.0 used to set the Phase 2 CO2 standards. To
understand the differences between GEM 3.0 and GEM 3.7, we recreated
the process used in 2016 to determine the numerical level of the Phase
2 standards. Without an adjustment to the resulting GEM output value,
these differences in GEM output values when compared to the Phase 2
final rule could be considered an effective change in stringency. In
light of GEM 3.7 output differences and considering CARB's comment, we
identified adjustment factors in that same docketed memo that could be
applied to the unrounded GEM 3.7 output to better ensure effective
stringency of the standards is maintained.\5\
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\5\ Id.
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The Truck and Engine Manufacturers Association (EMA) requested
additional time for its members to review the potential updates to the
model in GEM 3.7 and evaluate the impact of the adjustment factors made
available.\6\
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\6\ Charmley, Bill. Memorandum to Docket EPA-HQ-OAR-2019-0307.
``EPA discussions with the Truck and Engine Manufacturers
Association, and with the California Air Resources Board, regarding
Highway Heavy-Duty Technical Amendments.'' December 14, 2020. Docket
Number EPA-HQ-OAR-2019-0307-0092.
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As described in the Technical Amendments final rule, EPA released a
revised version of GEM (i.e., GEM 3.5.1) that corrected three errors in
GEM 3.5 and finalized provisions to specify GEM 3.5.1 without
adjustment factors as the compliance tool for meeting Phase 2
standards.\7\ GEM 3.5.1 includes the following updates to GEM 3.5:
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\7\ See the notice of final rulemaking for ``Improvements for
Heavy-Duty Engine and Vehicle Test Procedures, and other Technical
Amendments'' published in the Final Rule's section of today's
Federal Register, titled ``Improvements for Heavy-Duty Engine and
Vehicle Test Procedures,'' docket number EPA-HQ-OAR-2019-0307; FRL-
10018-52-OAR.
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Corrected duty cycle weighting factors for vocational
vehicles in the Heavy Heavy-Duty Multipurpose subcategory.
Corrected an idle map error when the cycle average engine
fuel mapping procedure is used for all three drive cycles.
Corrected a functional error that unnecessarily required
manufacturers to include transmission power loss data when using the
option to enter a unique (instead of default) k-factor for the torque
converter.

[[Page 34192]]

III. Proposed Updates to GEM

In this notice of proposed rulemaking, as detailed further in this
section, we are proposing to revise GEM and to revise GEM's test
procedures to include adjustment factors after consideration of
comments solicited and received on the Technical Amendments proposed
rule. We request comment only on these specific revisions and are not
proposing changes to or seeking comment on any other amendments
included in the Technical Amendments proposed or final rule.
We are releasing GEM version 3.8 for notice and comment.\8\ The
proposed GEM 3.8 allows additional compliance flexibilities and
improves the vehicle simulation by incorporating the following
improvements relative to GEM 3.5.1:
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\8\ Greenhouse gas Emissions Model (GEM) Phase 2, Version 3.8,
December 2020. A working version of this software is also available
for download at https://www.epa.gov/regulations-emissions-vehicles-and-engines/greenhouse-gas-emissions-model-gem-medium-and-heavy-duty.
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Changed limits on engine input to allow small negative
torque inputs.
Corrected how GEM adjusts the idle fueling of the
transient cycle by using the same idle duration time both for
subtracting the idle fuel rate from the transient cycle average engine
fuel map and for adding back in the simulated idle fuel rate.
Added an option for vocational vehicles to input a value
for neutral coasting in GEM and amend the related test procedure in 40
CFR 1037.520(j)(1).
Corrected manual and automated manual transmissions to
perform clutched upshifts for Heavy HDV.
We request comment on the revisions listed above.
As noted in a memorandum to the docket, the resulting standards
generated using GEM 3.8 in place of GEM 3.0 were, on average, 0.58
percent lower for tractors and 0.20 percent higher for vocational
vehicles, with the greatest difference (an increase of 1.3 percent)
occuring in a few of the custom chassis standards.\9\ To ensure that
these changes to GEM do not change the effective stringency of the
Phase 2 CO2 standards, we propose a revision to the test
procedures in 40 CFR 1037.520(o) to include a table of adjustment
factors to be applied to the unrounded GEM 3.8 output to correct the
differences. We request comment on this proposed revision to 40 CFR
1037.520(o). EPA also requests comment on whether EPA should
incorporate the adjustment factors directly into the GEM model, if EPA
is able to develop a version of the GEM model which properly
incorporates the adjustment factors.
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\9\ Sanchez, James, Memorandum to Docket EPA-HQ-OAR-2019-0307.
Process of Using GEM to Set Vehicle Standards. December 4, 2020.
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We are proposing to incorporate by reference into the regulations
the revised version, GEM 3.8, for manufacturers to demonstrate
compliance with the Phase 2 standards, including obtaining a
certificate of conformity and submitting end-of-year reports. For MY
2021, we are proposing to allow use of GEM 3.5.1 under Sec.
1037.150(bb) as an interim provision, but to limit this optional use of
GEM 3.5.1 for demonstrating compliance with the Phase 2 standards,
including obtaining a certificate of conformity and submitting end-of-
year reports, to MY 2021 vehicles only. A manufacturer who opts to use
GEM 3.5.1 for MY 2021 is required to apply GEM 3.5.1 across its entire
MY 2021 U.S.-directed production volume. We also propose to allow MY
2021 data based on the use of GEM 3.5.1 to be used for carryover
requests for certificates of conformity for MY 2022 and future years
for qualifying vehicles under Sec. 1037.235(d); however, manufacturers
would still need to use GEM 3.8 for end-of-year reporting for MY 2022
and later. Under this proposal, GEM 3.8 would need to be used for all
other certificates of conformity for MY 2022 and later. Due to the
model improvements and flexibilities available in GEM 3.8 relative to
GEM 3.5.1, we request comment on the appropriateness of requiring that
GEM 3.8 be used for MY 2021 end-of-year reports even if MY 2021
certificates of conformity were obtained using GEM 3.5.1. Finally, we
are proposing that if an engine fuel map was run on an engine using a
cycle generated from GEM 3.5.1 for MY 2021 and the manufacturer of that
engine applies for carryover certification for MY 2022 or later, the
manufacturer would not need to rerun the engine fuel map. We request
comment on these requirements, allowable uses, and limitations proposed
for each of these revised GEM model versions, including the use of GEM
3.5.1 for MY 2021 and carryover applications.

IV. Statutory Authority and Executive Order Reviews

Additional information about these statutes and Executive Orders
can be found at http://www2.epa.gov/laws-regulations/laws-and-executive-orders.

A. Executive Order 12866: Regulatory Planning and Review and Executive
Order 13563: Improving Regulation and Regulatory Review

This action is not a significant regulatory action and was
therefore not submitted to the Office of Management and Budget (OMB)
for review.

B. Regulatory Flexibility Act (RFA)

I certify that this action will not have a significant economic
impact on a substantial number of small entities under the RFA. In
making this determination, the impact of concern is any significant
adverse economic impact on small entities. An agency may certify that a
rule will not have a significant economic impact on a substantial
number of small entities if the rule relieves regulatory burden, has no
net burden or otherwise has a positive economic effect on the small
entities subject to the rule. This action is designed to reduce testing
burdens, increase compliance flexibility, and make various corrections
and adjustments to compliance provisions; as a result, we anticipate no
costs associated with this rule. We have therefore concluded that this
action will have no net regulatory burden for directly regulated small
entities.

C. Unfunded Mandates Reform Act (UMRA)

This action does not contain any unfunded mandate as described in
UMRA, 2 U.S.C. 1531-1538, and does not significantly or uniquely affect
small governments. This action imposes no enforceable duty on any
state, local or tribal governments. Requirements for the private sector
do not exceed $100 million in any one year.

D. Executive Order 13132: Federalism

This action does not have federalism implications. It will not have
substantial direct effects on the states, on the relationship between
the national government and the states, or on the distribution of power
and responsibilities among the various levels of government.

E. Executive Order 13175: Consultation and Coordination With Indian
Tribal Governments

This action does not have tribal implications as specified in
Executive Order 13175. This rule will be implemented at the Federal
level and affects engine and vehicle manufacturers. Thus, Executive
Order 13175 does not apply to this action.

F. Executive Order 13045: Protection of Children From Environmental
Health Risks and Safety Risks

This action is not subject to Executive Order 13045 because it is
not economically significant as defined in Executive Order 12866, and
because the EPA does not believe the environmental

[[Page 34193]]

health or safety risks addressed by this action present a
disproportionate risk to children. There are no environmental health or
safety risks created by this action that could present a
disproportionate risk to children.

G. Executive Order 13211: Actions Concerning Regulations That
Significantly Affect Energy Supply, Distribution or Use

This action is not subject to Executive Order 13211, because it is
not a significant regulatory action under Executive Order 12866.

H. National Technology Transfer and Advancement Act (NTTAA) and 1 CFR
Part 51

Section 12(d) of the National Technology Transfer and Advancement
Act of 1995 (``NTTAA''), Public Law 104-113, 12(d) (15 U.S.C. 272 note)
directs EPA to use voluntary consensus standards in its regulatory
activities unless to do so would be inconsistent with applicable law or
otherwise impractical. Voluntary consensus standards are technical
standards (e.g., materials specifications, test methods, sampling
procedures, and business practices) that are developed or adopted by
voluntary consensus standards bodies. NTTAA directs agencies to provide
Congress, through OMB, explanations when the Agency decides not to use
available and applicable voluntary consensus standards. This action
involves technical standards.
Except for the reference discussed below, the standards included in
the regulatory text as incorporated by reference in 40 CFR part 1037
were all previously approved for IBR and no change is proposed in this
action.
In accordance with the requirements of 1 CFR 51.5, we are proposing
to incorporate by reference a new version of the Greenhouse gas
Emissions Model (GEM), which we use for certifying heavy-duty highway
vehicles to the greenhouse gas emission standards in 40 CFR part 1037.
The model calculates emission rates for heavy-duty highway vehicles
based on input values defined by the manufacturer. The model is
available as noted in the amended regulations at 40 CFR 1037.810.

I. Executive Order 12898: Federal Actions To Address Environmental
Justice in Minority Populations and Low-Income Populations

The EPA believes this action does not have disproportionately high
and adverse human health or environmental effects on minority
populations, low-income populations or indigenous peoples, as specified
in Executive Order 12898 (59 FR 7629, February 16, 1994). Due to the
small environmental impact, this regulatory action will not have a
disproportionate adverse effect on minority populations, low-income
populations, or indigenous peoples.

List of Subjects

40 CFR Part 1036

Administrative practice and procedure, Air pollution control,
Confidential business information, Environmental protection, Greenhouse
gases, Labeling, Motor vehicle pollution, Reporting and recordkeeping
requirements, Warranties.

40 CFR Part 1037

Administrative practice and procedure, Air pollution control,
Confidential business information, Environmental protection,
Incorporation by reference, Labeling, Motor vehicle pollution,
Reporting and recordkeeping requirements, Warranties.

Jane Nishida,
Acting Administrator.

For the reasons set out in the preamble, we propose to amend title
40, chapter I of the Code of Federal Regulations as set forth below.

PART 1036--CONTROL OF EMISSIONS FROM NEW AND IN-USE HEAVY-DUTY
HIGHWAY ENGINES

0
1. The authority citation for part 1036 continues to read as follows:

Authority: 42 U.S.C. 7401-7671q.

0
2. Amend Sec. 1036.150 by adding paragraph (r) to read as follows:

Sec. 1036.150 Interim provisions.

* * * * *
(r) Carryover fuel maps. You may use fuel maps from model year 2021
engines for certifying model year 2022 and later vehicles using
carryover provisions in Sec. 1036.235(d), even if the specified
version of the GEM simulation tool to generate duty cycles for fuel
mapping changes for those later model years.

PART 1037--CONTROL OF EMISSIONS FROM NEW HEAVY-DUTY MOTOR VEHICLES

0
3. The authority citation for part 1037 continues to read as follows:

Authority: 42 U.S.C. 7401-7671q.

0
4. Amend Sec. 1037.150 by adding paragraph (bb) to read as follows:

Sec. 1037.150 Interim provisions.

* * * * *
(bb) Transition to updated GEM. Vehicle manufacturers may
demonstrate compliance with Phase 2 GHG standards in model year 2021
vehicles using GEM Phase 2, Version 3.5.1 (incorporated by reference in
Sec. 1037.810). Each vehicle manufacturer must use a single version of
GEM for all its model year 2021 families. Vehicle manufacturers may use
GEM Phase 2, Version 3.5.1 for later model years only to certify
vehicle families from model year 2021 that qualify for using carryover
provisions in Sec. 1037.235(d).
0
5. Amend Sec. 1037.520 by revising the introductory text and paragraph
(j)(1) and adding paragraph (o) to read as follows:

Sec. 1037.520 Modeling CO2 emissions to show compliance for
vocational vehicles and tractors.

This section describes how to use the Greenhouse gas Emissions
Model (GEM) (incorporated by reference in Sec. 1037.810) to show
compliance with the CO2 standards of Sec. Sec. 1037.105 and
1037.106 for vocational vehicles and tractors. Use GEM version 2.0.1 to
demonstrate compliance with Phase 1 standards; use GEM Phase 2, Version
3.8 to demonstrate compliance with Phase 2 standards. Use good
engineering judgment when demonstrating compliance using GEM. See Sec.
1037.515 for calculation procedures for demonstrating compliance with
trailer standards.
* * * * *
(j) * * *
(1) Intelligent controls. Enter 2 for tractors with predictive
cruise control. This includes any cruise control system that
incorporates satellite-based global-positioning data for controlling
operator demand. For tractors without predictive cruise control and for
all vocational vehicles, enter 1.5 if they have neutral coasting,
unless good engineering judgment indicates that a lower percentage
should apply.
* * * * *
(o) Adjusting results for updated GEM. Adjust composite results
from GEM Phase 2, Version 3.8 using the following equation to account
for modeling changes relative to GEM Phase 2, Version 3.0:
[GRAPHIC] [TIFF OMITTED] TP29JN21.000

Where:

eCO2 = FEL CO2 Emissions from GEM.
AF = the adjustment factor from the following table:

[[Page 34194]]

Table 10 of Sec. 1037.520--Adjustment Factors for Composite Results From GEM Phase 2, Version 3.8
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Adjustment factor
Regulatory subcategory -----------------------------------------------------------
MY 2022-2023 MY 2024-2026 MY 2027-and-later
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Class 7 Day Cab Low Roof............................ -0.0104 -0.0090 -0.0094
Class 7 Day Cab Mid Roof............................ -0.0106 -0.0084 -0.0097
Class 7 Day Cab High Roof........................... -0.0088 -0.0084 -0.0090
Class 8 Day Cab Low Roof............................ -0.0062 -0.0079 -0.0068
Class 8 Sleeper Cab Low Roof........................ -0.0014 -0.0015 -0.0016
Class 8 Day Cab Mid Roof............................ -0.0059 -0.0062 -0.0064
Class 8 Sleeper Cab Mid Roof........................ -0.0013 0.0000 0.0000
Class 8 Day Cab High Roof........................... -0.0058 -0.0062 -0.0066
Class 8 Sleeper Cab High Roof....................... -0.0013 -0.0014 -0.0016
Class 8 Heavy Haul.................................. -0.0076 -0.0080 -0.0062
Multi-Purpose Light HDV Compression-ignition........ 0.0000 -0.0029 0.0000
Regional Light HDV Compression-ignition............. 0.0000 0.0000 0.0000
Urban Light HDV Compression-ignition................ 0.0000 0.0000 0.0000
Multi-Purpose Medium HDV Compression-ignition....... -0.0038 0.0000 0.0000
Regional Medium HDV Compression-ignition............ 0.0000 0.0000 0.0000
Urban Medium HDV Compression-ignition............... -0.0034 -0.0037 0.0000
Multi-Purpose Heavy HDV Compression-ignition........ 0.0038 0.0041 0.0043
Regional Heavy HDV Compression-ignition............. 0.0000 0.0000 0.0000
Urban Heavy HDV Compression-ignition................ 0.0065 0.0071 0.0037
Multi-Purpose Light HDV Spark-ignition.............. 0.0000 0.0000 -0.0027
Regional Light HDV Spark-ignition................... 0.0000 0.0000 0.0000
Urban Light HDV Spark-ignition...................... 0.0000 0.0000 0.0000
Multi-Purpose Medium HDV Spark-ignition............. 0.0000 0.0000 0.0000
Regional Medium HDV Spark-ignition.................. 0.0000 0.0000 0.0040
Urban Medium HDV Spark-ignition..................... 0.0030 0.0032 0.0034
School bus.......................................... -0.0034 -0.0034 0.0000
Motor home.......................................... 0.0000 0.0000 0.0000
Coach bus........................................... 0.0000 0.0000 0.0049
Other bus........................................... 0.0067 0.0067 0.0000
Refuse hauler....................................... 0.0096 0.0096 0.0034
Concrete mixer...................................... 0.0125 0.0125 0.0127
Mixed-use vehicle................................... 0.0125 0.0125 0.0127
Emergency vehicle................................... 0.0123 0.0123 0.0125
----------------------------------------------------------------------------------------------------------------

0
6. Amend Sec. 1037.810 by revising paragraph (c) to read as follows:

Sec. 1037.810 Incorporation by reference.

* * * * *
(c) U.S. EPA, Office of Air and Radiation, 2565 Plymouth Road, Ann
Arbor, MI 48105, www.epa.gov.
(1)(i) Greenhouse gas Emissions Model (GEM), Version 2.0.1,
September 2012 (``GEM version 2.0.1''), IBR approved for Sec.
1037.520.
(ii) Greenhouse gas Emissions Model (GEM) Phase 2, Version 3.5.1,
November 2020 (``GEM Phase 2, Version 3.5.1''); IBR approved for Sec.
1037.150(bb).
(iii) Greenhouse gas Emissions Model (GEM) Phase 2, Version 3.8,
November 2020 (``GEM Phase 2, Version 3.8''); IBR approved for Sec.
1037.520.
(iv) GEM's MATLAB/Simulink Hardware-in-Loop model, Version 3.8,
December 2020 (``GEM HIL model''); IBR approved for Sec. 1037.550(a).
(2) The computer code for these models is available as noted in
paragraph (a) of this section. A working version of the software is
also available for download at https://www.epa.gov/regulations-emissions-vehicles-and-engines/greenhouse-gas-emissions-model-gem-medium-and-heavy-duty.
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[FR Doc. 2021-05305 Filed 6-28-21; 8:45 am]
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