----------------------------------------------------------------------------------------------------------------
                  EPA Standard for Vehicle with SI Engine Effective MY 2021 (gram CO2/ton-mile)
----------------------------------------------------------------------------------------------------------------
Urban...........................................................             320             203             214

Multi-Purpose...................................................             329             205             216
Regional........................................................             343             201             204
----------------------------------------------------------------------------------------------------------------

         Table V-5--Proposed NHTSA Fuel Consumption Standards for MY 2021 Class 2b-8 Vocational Vehicles
----------------------------------------------------------------------------------------------------------------
                                                                   Light heavy-
                           Duty cycle                             duty class 2b-   Medium heavy-   Heavy heavy-
                                                                         5        duty class 6-7   duty class 8
----------------------------------------------------------------------------------------------------------------
    NHTSA Standard for Vehicle with CI Engine Effective MY 2021 (Fuel Consumption gallon per 1,000 ton-mile)
----------------------------------------------------------------------------------------------------------------
Urban...........................................................         29.0766         18.4676         19.4499
Multi-Purpose...................................................         29.9607         18.6640         19.6464
Regional........................................................         31.2377         18.2711         18.5658
----------------------------------------------------------------------------------------------------------------
    NHTSA Standard for Vehicle with SI Engine Effective MY 2021 (Fuel Consumption gallon per 1,000 ton-mile)
----------------------------------------------------------------------------------------------------------------
Urban...........................................................         36.0077         22.8424         24.0801
Multi-Purpose...................................................         37.0204         23.0674         24.3052
Regional........................................................         38.5957         22.6173         22.9549
----------------------------------------------------------------------------------------------------------------

                Table V-6--Proposed EPA CO2 Standards for MY 2024 Class 2b-8 Vocational Vehicles
----------------------------------------------------------------------------------------------------------------
                                                                   Light heavy-
                           Duty cycle                             duty class 2b-   Medium heavy-   Heavy heavy-
                                                                         5        duty class 6-7   duty class 8
----------------------------------------------------------------------------------------------------------------
                  EPA Standard for Vehicle with CI Engine Effective MY 2024 (gram CO2/ton-mile)
----------------------------------------------------------------------------------------------------------------
Urban...........................................................             284             179             190
Multi-Purpose...................................................             292             181             192
Regional........................................................             304             178             182
----------------------------------------------------------------------------------------------------------------
                  EPA Standard for Vehicle with SI Engine Effective MY 2024 (gram CO2/ton-mile)
----------------------------------------------------------------------------------------------------------------
Urban...........................................................             312             197             208
Multi-Purpose...................................................             321             199             210
Regional........................................................             334             196             199
----------------------------------------------------------------------------------------------------------------

         Table V-7--Proposed NHTSA Fuel Consumption Standards for MY 2024 Class 2b-8 Vocational Vehicles
----------------------------------------------------------------------------------------------------------------
                                                                   Light heavy-
                           Duty cycle                             duty class 2b-   Medium heavy-   Heavy heavy-
                                                                         5        duty class 6-7   duty class 8
----------------------------------------------------------------------------------------------------------------
    NHTSA Standard for Vehicle with CI Engine Effective MY 2024 (Fuel Consumption gallon per 1,000 ton-mile)
----------------------------------------------------------------------------------------------------------------
Urban...........................................................         27.8978         17.5835         18.6640
Multi-Purpose...................................................         28.6837         17.7800         18.8605
Regional........................................................         29.8625         17.4853         17.8782
----------------------------------------------------------------------------------------------------------------
    NHTSA Standard for Vehicle with SI Engine Effective MY 2024 (Fuel Consumption gallon per 1,000 ton-mile)
----------------------------------------------------------------------------------------------------------------
Urban...........................................................         35.1075         22.1672         23.4050
Multi-Purpose...................................................         36.1202         22.3923         23.6300
Regional........................................................         37.5830         22.0547         22.3923
----------------------------------------------------------------------------------------------------------------

                Table V-8--Proposed EPA CO2 Standards for MY 2027 Class 2b-8 Vocational Vehicles
----------------------------------------------------------------------------------------------------------------
                                                                   Light heavy-
                           Duty cycle                             duty class 2b-   Medium heavy-   Heavy heavy-
                                                                         5        duty class 6-7   duty class 8
----------------------------------------------------------------------------------------------------------------
                  EPA Standard for Vehicle with CI Engine Effective MY 2027 (gram CO2/ton-mile)
----------------------------------------------------------------------------------------------------------------
Urban...........................................................             272             172             182
Multi-Purpose...................................................             280             174             183

Regional........................................................             292             170             174
----------------------------------------------------------------------------------------------------------------
                  EPA Standard for Vehicle with SI Engine Effective MY 2027 (gram CO2/ton-mile)
----------------------------------------------------------------------------------------------------------------
Urban...........................................................             299             189             196
Multi-Purpose...................................................             308             191             198
Regional........................................................             321             187             188
----------------------------------------------------------------------------------------------------------------

         Table V-9--Proposed NHTSA Fuel Consumption Standards for MY 2027 Class 2b-8 Vocational Vehicles
----------------------------------------------------------------------------------------------------------------
                                                                   Light heavy-
                           Duty cycle                             duty class 2b-   Medium heavy-   Heavy heavy-
                                                                         5        duty class 6-7   duty class 8
----------------------------------------------------------------------------------------------------------------
    NHTSA Standard for Vehicle with CI Engine Effective MY 2027 (Fuel Consumption gallon per 1,000 ton-mile)
----------------------------------------------------------------------------------------------------------------
Urban...........................................................         26.7191         16.8959         17.8782
Multi-Purpose...................................................         27.5049         17.0923         17.9764
Regional........................................................         28.6837         16.6994         17.0923
----------------------------------------------------------------------------------------------------------------
    NHTSA Standard for Vehicle with SI Engine Effective MY 2027 (Fuel Consumption gallon per 1,000 ton-mile)
----------------------------------------------------------------------------------------------------------------
Urban...........................................................         33.6446         21.2670         22.0547
Multi-Purpose...................................................         34.6574         21.4921         22.2797
Regional........................................................         36.1202         21.0420         21.1545
----------------------------------------------------------------------------------------------------------------

    As with the other regulatory categories of heavy-duty vehicles,
NHTSA and EPA are are proposing standards that apply to Class 2b-8
vocational vehicles at the time of production, and EPA is proposing
standards for a specified period of time in use (e.g., throughout the
regulatory useful life of the vehicle). The derivation of the standards
for these vehicles, as well as details about the proposed provisions
for certification and implementation of these standards, are discussed
in more detail later in this notice and in the draft RIA.
(b) Proposed HFC Leakage Standards
    The Phase 1 GHG standards do not include standards to control
direct HFC emissions from air conditioning systems on vocational
vehicles. EPA deferred such standards due to ``the complexity in the
build process and the potential for different entities besides the
chassis manufacturer to be involved in the air conditioning system
production and installation''. See 76 FR 57194. During our stakeholder
outreach conducted for Phase 2, we learned that the majority of
vocational vehicles are sold as cab-completes with the dashboard-
mounted air conditioning systems installed by the chassis manufacturer.
For those vehicles that have A/C systems installed by a second stage
manufacturer, EPA is proposing revisions to our regulations that would
resolve the issues identified in Phase 1, in what we believe is a
practical and feasible manner, as described below in Section V.E.
    For the above reasons, in Phase 2, EPA now believes that it is
reasonable to propose A/C refrigerant leakage standards for Class 2b-8
vocational vehicles, beginning with the 2021 model year. Chassis sold
as cab-completes typically have air conditioning systems installed by
the chassis manufacturer. For these configurations, the process for
certifying that low leakage components are used would follow the system
in place currently for comparable systems in tractors. In the case
where a chassis manufacturer would rely on a second stage manufacturer
to install a compliant air conditioning system, the chassis
manufacturer must follow the proposed delegated assembly provisions
described below in Section V.E.
(4) Proposed Exemptions and Exclusions
(a) Proposed Standards for Emergency Vehicles
    Emergency vehicles are covered by the Phase 1 program at the same
level of stringency as any other vocational vehicle. In discussions
with representatives of the Fire Apparatus Manufacturers Association,
the agencies have learned that chassis manufacturers of fire apparatus
are currently able to obtain compliant engines and tires with the
coefficient of rolling resistance allowing compliance with the Phase 1
standards. The agencies are proposing in Phase 2 to allow emergency
vehicles to meet less stringent standards than other vocational
vehicles. There are two reasons for doing so. First, as the level of
complexity of Phase 2 would increase with the need for additional
technologies aimed to improve driveline efficiency, the compliance
burden would be disproportionately high for a company that manufactures
small volumes of specialized chassis. The ability of such a company to
benefit from averaging would be limited, as would be the ability to
spread compliance costs across many vehicles. The second and more
important reason is that emergency vehicles, which are necessarily
built for high levels of performance and reliability, would likely
sacrifice some levels of function to attain the proposed Phase 2
standards. For example, vehicles with large engines, high-torque
powertrains, and tires designed with deep tread would likely be
deficit-producing vehicles if manufacturers needed to certify an
emergency vehicle family to the primary proposed standards.
    In the MY 2017-2025 light-duty rule, the agencies adopted an
exclusion for emergency and police vehicles from GHG and fuel economy
standards.\265\ As described in that rule, the unique features of
purpose-built emergency vehicles, such as high rolling resistance

tires, reinforced suspensions, and special calibrations of engines and
transmissions, have the effect of raising their GHG emissions. The
agencies determined in that rule that an exemption was appropriate
because the technological feasibility issues for emergency vehicles
went beyond those of other high-performance vehicles, and vehicles with
these performance characteristics must continue to be made available in
the market. The agencies do not believe that non-emergency vocational
vehicles are designed for the severe duty cycles that are experienced
by emergency vehicles, and therefore do not face the same potential
constraints in terms of vehicle design and the application of
technology.
---------------------------------------------------------------------------

    \265\ See 77 FR 62653, October 12, 2012.
---------------------------------------------------------------------------

    In conducting an independent technological feasibility assessment
for heavy-duty emergency vehicles, the agencies believe that some GHG
and fuel saving technologies could reasonably be applied without
compromising vehicle utility. However, these vehicles are designed,
built, and operated so differently than other vocational vehicles that
we believe keeping them in the same averaging sets as other vocational
vehicles in Phase 2 would not be appropriate and thus a separate
standard (evaluated from a baseline specific to these vehicles) is
warranted.
    Our feasibility analysis and the available tire data indicate that
emergency vehicle manufacturers can reasonably continue to apply tires
with the Phase 1 level tire CRR performance, in the Phase 2 program. We
have also learned that a variety of vehicle-level technologies are
being developed specifically for emergency vehicles, to maintain on-
board electronics without excessive idling. Modern fire apparatus and
ambulances typically have multiple computers and other electronic
devices on-board, each of which requires power and continues to draw
electricity when the vehicle is parked and the crew is responding to an
emergency, which could take several hours. Most on-board batteries and
alternators are not capable of sustaining these power demands for any
length of time, so emergency vehicles must either operate in a high-
idle mode or adopt one of several possible technologies that can assist
with electrical load management. Some of these technologies can enable
an emergency vehicle to shut down the main engine and drastically
reduce idle emissions.\266\ NHTSA and EPA have not based the proposed
emergency vehicle standards on use of idle reduction technologies
because we do not believe the regular neutral idle and stop-start
technologies we project for other vocational vehicles could apply
equally to emergency vehicles, and we do not have enough information
about this subset of idle reduction technologies that is designed for
extended electrical load management to either estimate an effectiveness
value or determine an appropriate market adoption rate. The agencies
request comment on whether we should include any market adoption rate
of idle reduction technologies for emergency vehicles, as part of the
basis for the Phase 2 emergency vocational vehicle standard.
---------------------------------------------------------------------------

    \266\ See ``How to solar power a fire truck or ambulance,''
available at http://www.firerescue1.com/fire-products/apparatus-accessories/articles/1934440-How-to-solar-power-a-fire-truck-or-ambulance/, accessed November 2014.
---------------------------------------------------------------------------

    To address both the technical feasibility and the compliance
burden, the agencies are proposing less stringent standards that also
have a simplified compliance method. Because the potential trade-offs
between performance and fuel efficiency apply equally to any emergency
vehicle manufacturer, the agencies propose that these less stringent
standards would apply for commercial chassis manufacturers of emergency
vehicles, as well as for custom chassis manufacturers. The standard for
vehicles identified at the time of certification as being intended for
emergency service would be predicated solely on the continued use of
lower rolling resistance tires, at the Phase 2 baseline level (i.e.
compliant with Phase 1).\267\
---------------------------------------------------------------------------

    \267\ See 40 CFR 86.1803-01 for the applicable definition of
emergency vehicle.
---------------------------------------------------------------------------

    With respect to standards for engines used in these emergency
vehicles, based on what we have learned from discussions with engine
manufacturers, we understand that engines designed for heavy-duty
emergency vehicles are generally higher-emitting than other engines.
However, if we maintain a separate engine standard and regulatory
flexibility such as ABT, fire apparatus manufacturers would be able to
obtain engines that, on average, meet the proposed Phase 2 engine
standards. The agencies further recognize that the proposed engine map
inputs to GEM in the primary program would pose a difficulty for
emergency vehicle manufacturers. If we required engine-specific inputs
then these manufacturers would have to apply extra vehicle technologies
to compensate for the necessary but higher-emitting engine. The
agencies are therefore not proposing to recognize engine performance as
part of the vehicle standard for emergency vehicles. Manufacturers of
these vehicles would be expected to install an engine that is certified
to the applicable separate Phase 2 engine standard. However, under the
simplified compliance method we are proposing, emergency vehicle
manufacturers would not follow the otherwise applicable Phase 2
proposed approach of entering an engine map in GEM. Instead a Phase 1
style GEM interface would be made available, where an EPA default
engine specified by rule would be simulated in GEM. The agencies
request comments on the merits of using an equation-based compliance
approach for emergency vehicle manufacturers, similar to the approach
proposed for trailer manufacturers and described in Section IV.F.
    This approach is consistent with the approach recommended by the
Small Business Advocacy Review Panel, which believed it would be
feasible for small emergency vehicle manufacturers to install a Phase
2-compliant engine, but recommended a simplified certification approach
to reduce the number of required GEM inputs. Consistent with the
recommendations of this panel, the agencies are asking for comments on
whether there would be enough fuel consumption and CO2
emissions benefits achieved by use of LRR tires in emergency vehicles
to justify requiring small business emergency chassis manufacturers to
adopt them.
    We expect some commercial chassis manufacturers that serve the
emergency vehicle market may have the ability to meet the proposed
Phase 2 standards of our primary program when including emergency
vehicles in their averaging sets. Even so, we are proposing that they
have the option to comply with the less stringent standards, because
there are fewer opportunities to improve fuel efficiency on emergency
vehicles, which (as noted) are designed for high levels of performance
and severe duty. The agencies expect that this compliance path would be
most needed by custom chassis manufacturers who serve the emergency
vehicle market. Custom chassis manufacturers typically offer a narrow
range of products with low sales volumes. Therefore, fleet averaging
would provide a lower level of compliance flexibility, and there would
be less opportunity to spread the costs of developing advanced
technologies across a large number of vehicles. Further, many custom
chassis manufacturers do not qualify as small entities under the SBA
regulations. Thus, the agencies believe that existence of program-wide
ABT does not vitiate

the need to propose alternative, less stringent standards for emergency
vehicles.
    Table V-10 below presents the proposed numerical standards to which
an emergency vehicle chassis would be certified under this provision.
Emergency vehicles certified to these proposed emergency vehicle
standards would be ineligible to generate credits. The proposed
standards shown below were derived by building a model of three
baseline vehicles (LHD, MHD, HHD) using attributes similar to those
developed for the primary program as assigned to the Urban drive cycle
subcategories. By modeling a 2021-compliant engine and tires with CRR
of 7.7, the MY 2021 standards were derived using GEM. Details of these
configurations are provided in the draft RIA Chapter 2.

             Table V-10--Proposed Standards for Class 2b-8 Emergency Vehicles for MY 2021 and Later
----------------------------------------------------------------------------------------------------------------
                                                                   Light heavy-
                       Implementation year                        duty class 2b-   Medium heavy-   Heavy heavy-
                                                                         5        duty class 6-7   duty class 8
----------------------------------------------------------------------------------------------------------------
                           Proposed EPA Emergency Vehicle Standard (gram CO2/ton-mile)
----------------------------------------------------------------------------------------------------------------
MY2021..........................................................             312             195             215
----------------------------------------------------------------------------------------------------------------
             Proposed NHTSA Emergency Vehicle Standard (Fuel Consumption gallon per 1,000 ton-mile)
----------------------------------------------------------------------------------------------------------------
MY2021..........................................................         30.6483         19.1552         21.1198
----------------------------------------------------------------------------------------------------------------

    The agencies have estimated the costs of vocational vehicle
technology packages, as presented below in Table V-20 to Table V-22.
The technologies on which the proposed emergency vehicle standards are
based include engines, LRR tires, and leak-tight air conditioning
systems. Using the estimated costs of those technologies as presented,
the agencies estimate that the average cost for a heavy heavy-duty or
medium-heavy-duty emergency vehicle to meet the proposed emergency
vehicle standards would be approximately $463 in MY 2027, and the
average cost for a light heavy-duty emergency vehicle would be
approximately $497 in MY 2027. To derive these estimates, the agencies
have combined the $7 cost of LRR tires that is presented in Table V-20
with the engine and air conditioning costs presented in Table V-22. The
agencies are not aware of any emergency vehicle manufacturer that
produces engines, thus most of these costs would be borne by engine
manufacturers. While some of the added engine costs may be passed on to
emergency vehicle manufacturers and vehicle owners/operators, the
overall costs of these technologies are on the order of the Phase 1
vocational vehicle program costs, which are highly cost-effective.
    To ensure that only emergency vehicle chassis would be able to
certify to these less stringent standards, the agencies propose that
manufacturers identify vehicles using the definition at 40 CFR 86.1803-
01, which for Phase 2 purposes would be an ambulance or a fire truck.
Manufacturers have informed us that it is feasible to identify such
vehicles using sales codes or the presence of specialty attributes. The
agencies request comment on the merits and drawbacks of aligning the
definition of emergency vehicle for purposes of the Phase 2 program
with the definition of emergency vehicle for purposes of the light-duty
GHG provisions under 40 CFR 86.1818, which includes additional vehicles
such as those used by law enforcement.
    According to the International Council on Clean Transportation
(ICCT), less than one percent of all new heavy-duty truck registrations
from 2003 to 2007 were emergency vehicles.\268\ On average, the ICCT's
data suggest that approximately 5,700 new emergency vehicles are sold
in the U.S. each year; about 0.8 percent of the 3.4 million new heavy-
duty trucks registered between 2003 and 2007. According to the Fire
Apparatus Manufacturers Association, the annual VMT of the newest
emergency vehicles ranges from approximately 2,000 to 8,000 miles, as
documented in their 2004 Fire Apparatus Duty Cycle White Paper.\269\
Because there are relatively few of these vehicles and they travel a
relatively small number of miles, the agencies believe that setting
less stringent GHG and fuel consumptions standards for these vehicles
would not detract from the greater benefits of this rulemaking, and
such separate standards are warranted in any case.
---------------------------------------------------------------------------

    \268\ ICCT, May 2009, ``Heavy-Duty Vehicle Market Analysis:
Vehicle Characteristics & Fuel Use, Manufacturer Market Shares.''
    \269\ Fire Apparatus Manufacturer's Association, Fire Apparatus
Duty Cycle White Paper, August 2004, available at http://www.deepriverct.us/firehousestudy/reports/Apparatus-Duty-Cycle.pdf.
---------------------------------------------------------------------------

(b) Possible Standards for Other Custom Chassis Manufacturers
    The agencies request comment on extending the above simplified
compliance procedure and less stringent Phase 2 standards to other
custom chassis manufacturers--those who offer such a narrow range of
products that averaging is not of practical value as a compliance
flexibility, and for whom there are not large sales volumes over which
to distribute technology development costs. Custom chassis
manufacturers that are not small businesses must comply with the Phase
1 standards and are generally doing so, by installing tires with the
required coefficient of rolling resistance. We are aware of a handful
of U.S. chassis manufacturers serving the recreational vehicle and bus
markets who we believe would have a disproportionate compliance burden,
should we require compliance with the primary proposed Phase 2
standards.
    According to the MOVES model forecast, there will be approximately
1,000 commercial intercity coach buses, 5,000 transit buses, 40,000
school buses, and 90,000 recreational vehicles manufactured new for MY
2018.\270\ In each of these markets, specialty chassis manufacturers
compete with large vertically integrated manufacturers. We request
comment on the merits of offering less stringent standards to small
volume chassis manufacturers, and seek comment as well as to other
factors the agencies should consider to ensure this

approach would not have unintended consequences for businesses
competing in the vocational vehicle market.
---------------------------------------------------------------------------

    \270\ Vehicle populations are estimated using MOVES2014. More
information on projecting populations in MOVES is available in the
following report: USEPA (2015). ``Population and Activity of On-road
Vehicles in MOVES2014--Draft Report'' Docket No. EPA-HQ-OAR-2014-
0827.
---------------------------------------------------------------------------

    If the agencies were to adopt less stringent standards for custom
non-emergency chassis manufacturers, we would expect to limit this by
setting a maximum number of eligible vocational chassis annually for
each such manufacturer. The agencies request comment on an appropriate
sales volume to qualify for these possible standards, and also request
comment as to whether the sales volume thresholds should be different
for different markets. We further request comment on whether it would
adversely affect business competitiveness if custom chassis
manufacturers were held to a different standard than commercial chassis
manufacturers, and whether the agencies should consider allowing
commercial chassis manufacturers competing in these markets to sell a
limited number of chassis certified to a less stringent standard.
    As an alternative approach, the agencies request comment on
providing custom chassis manufacturers with additional lead time to
comply. For example, we could allow such manufacturers an additional
one or two years to meet each level of the primary proposed vocational
vehicle standards.
    If the agencies pursued the approach of less stringent standards,
we would likely adopt a simplified compliance procedure similar to the
one proposed for emergency vehicles. Custom chassis manufacturers would
not follow the otherwise applicable Phase 2 proposed approach of
entering an engine map in GEM. Instead, a Phase 1 style GEM interface
would be made available, where an EPA default engine specified by rule
would be simulated in GEM. The vehicle-level standard would be
predicated on a simpler set of technologies than the primary proposed
Phase 2 standard, most likely lower rolling resistance tires and idle
reduction. Because these would not be emergency vehicles, we believe
the performance of these vehicles would not be compromised by requiring
improvement in tire CRR beyond that of the Phase 1 level. The agencies
request comment on whether we should develop separate standards for
different vehicle types such as recreational vehicles and buses.
    The Small Business Advocacy Review Panel recommended that EPA seek
comment on how to design a small business vocational vehicle exemption
by means of a custom chassis volume exemption and what sales volume
would be an appropriate threshold. The agencies seek comments on all
aspects of an approach for custom vocational vehicle chassis
manufacturers that would enable us to adopt a final Phase 2 program
that would be consistent with the recommendations of the panel.
(c) Off-Road and Low-Speed Vocational Vehicle Exemptions
    The agencies are proposing to continue the exemptions in Phase 1
for off-road and low-speed vocational vehicles, with revision. See
generally 76 FR 57175. These provisions currently apply for vehicles
that are defined as ``motor vehicles'' per 40 CFR 85.1703, but may
conduct most of their operations off-road, such as drill rigs, mobile
cranes and yard hostlers. Vehicles qualifying under these provisions
must be built with engines certified to meet the applicable engine
standard, but need not comply with a vehicle-level GHG or fuel
consumption standard. In Phase 1, this typically means not needing to
install tires with a lower coefficient of rolling resistance. Because
manufacturers choosing to exempt vehicles (but not engines) based on
the criteria for heavy-duty off road vehicles at 40 CFR 1037.631 and 49
CFR 523.2 will for the first time provide a description to the agencies
of how they meet the qualifications for this exemption in their end-of-
the year reports in the spring of 2015, we do not have information
beyond what we knew at the time of the Phase 1 rules regarding how
broadly this provision is being used. Nonetheless, we are proposing to
discontinue the criterion for exemption based solely on use of tires
with maximum speed rating at or below 55 mph. The agencies are
concerned that tires are so easily replaced that this would be an
unreliable way to identify vehicles that truly need special
consideration. We are proposing to retain the qualifying criteria
related to design and use of the vehicle. We invite comments on the
proposed revisions to the qualifying criteria in the regulations,
including whether the rated speed of the tires should be retained, and
whether vehicles intended to be covered by this provision have
characteristics that are captured by the proposed criteria.

C. Feasibility of the Proposed Vocational Vehicle Standards

    This section describes the agencies' technological feasibility and
cost analysis in greater detail. Further detail on all of these
technologies can be found in the draft RIA Chapter 2.4 and Chapter 2.9.
The variation in the design and use of vocational vehicles has led the
agencies to project different technology solutions for each regulatory
subcategory. Manufacturers may also find additional means to reduce
emissions and lower fuel consumption than the technologies identified
by the agencies, and of course may adopt any compliance path they deem
most advantageous. The focus of this section is on the feasibility of
the proposed standards for non-emergency vocational vehicles. Further,
the agencies project that these technology packages would also be
feasible for vocational tractors. With typical driving patterns having
limited operation at highway speeds, vocational tractors would
appropriately be classified as vocational vehicles, with proposed
standards that would not be predicated on the performance of
aerodynamic devices. The agencies propose to allow vocational tractors
to follow the same subcategory assignment process as other vocational
vehicles. For example, a beverage tractor intended for local delivery
routes may have a driving pattern that is reasonably represented by the
proposed Urban test cycle. The agencies request comment on whether
vocational tractors would be deficit-generating vehicles if certified
as vocational vehicles, where performance would be measured against the
proposed vocational vehicle baseline configurations. For example, if a
tractor were designed with a higher power engine to carry a heavier
payload than presumed in the GEM baseline for that subcategory, would
GEM return a value that poorly represents the real world performance of
that vehicle, and if so, would that merit a different certification
approach for vocational tractors?
    NHTSA and EPA collected information on the cost and effectiveness
of fuel consumption and CO2 emission reducing technologies
from several sources. The primary sources of information were the
Southwest Research Institute evaluation of heavy-duty vehicle fuel
efficiency and costs for NHTSA,\271\ the 2010 National Academy of
Sciences report of Technologies and Approaches to Reducing the Fuel
Consumption of Medium- and Heavy-Duty Vehicles,\272\ TIAX's assessment
of technologies to support the NAS panel report,\273\ the technology
cost analysis conducted by

ICF for EPA,\274\ and the 2009 report from Argonne National Laboratory
on Evaluation of Fuel Consumption Potential of Medium and Heavy Duty
Vehicles through Modeling and Simulation.\275\
---------------------------------------------------------------------------

    \271\ Reinhart, T, 2015. Commercial Medium- and Heavy-Duty (MD/
HD) Truck Fuel Efficiency Technology Study--Reports #1 and #2.
Washington, DC: National Highway Traffic Safety Administration; and
Schubert, R., Chan, M., Law, K. 2015, Commercial Medium- and Heavy-
Duty (MD/HD) Truck Fuel Efficiency Cost Study. Washington, DC:
National Highway Traffic Safety Administration.
    \272\ See NAS Report, Note 136, above.
    \273\ See TIAX 2009, Note 137, above.
    \274\ See ICF 2010, Note 139, above.
    \275\ Argonne National Laboratory, ``Evaluation of Fuel
Consumption Potential of Medium and Heavy Duty Vehicles through
Modeling and Simulation.'' October 2009
---------------------------------------------------------------------------

(1) What technologies are the agencies considering to reduce the
CO2 emissions and fuel consumption of vocational vehicles?
    In assessing the feasibility of the proposed Phase 2 vocational
vehicle standards, the agencies evaluated a suite of technologies,
including workday idle reduction, improved tire rolling resistance,
improved transmissions, improved axles, and weight reduction, as well
as their impact on reducing fuel consumption and GHG emissions. The
agencies also evaluated aerodynamic technologies and full electric
vehicles.
    As discussed above, vocational vehicles may be powered by either SI
or CI engines. The technologies and feasibility of the proposed engine
standards are discussed in Section II. At the vehicle level, the
agencies have considered the same suite of technologies and have
applied the same reasoning for including or rejecting these vehicle-
level technologies as part of the basis for the proposed standards,
regardless of whether the vehicle is powered by a CI or SI engine. With
the exception of the MY 2027 proposed standards, the analysis below
does not distinguish between vehicles with different types of engines.
The resulting proposed vehicle standards do reflect the differences
arising from the performance of different types of engines over the GEM
cycles.
(a) Vehicle Technologies Considered in Standard-Setting
    The agencies note that the effectiveness values estimated for the
technologies may represent average values, and do not reflect the
potentially-limitless combination of possible values that could result
from adding the technology to different vehicles. For example, while
the agencies have estimated an effectiveness of 0.5 percent for low
friction axle lubricants, each vehicle could have a unique
effectiveness estimate depending on the baseline axle's oil viscosity
rating. For purposes of this proposed rulemaking, NHTSA and EPA believe
that employing average values for technology effectiveness estimates is
an appropriate way of recognizing the potential variation in the
specific benefits that individual manufacturers (and individual
vehicles) might obtain from adding a given technology. There may be
real world effectiveness that exceeds or falls short of the average,
but on-balance the agencies believe this is the most practicable
approach for determining the wide ranging effectiveness of technologies
in the diverse vocational vehicle arena.
(i) Transmissions
    Transmission improvements present a significant opportunity for
reducing fuel consumption and CO2 emissions from vocational
vehicles. Transmission efficiency is important for many vocational
vehicles as their duty cycles involve high percentages of driving under
transient operation. The three categories of transmission improvements
the agencies considered for Phase 2 are driveline optimization,
architectural improvements, and hybrid powertrain systems.
    The agencies believe an effective way to derive efficiency
improvements from a transmission is by optimizing it with the engine
and other driveline components to balance both performance needs and
fuel savings. However, many vocational vehicles today are not operating
with such optimized systems. Because customers are able to specify
their preferred components in a highly customized build process, many
vocational vehicles are assembled with components that were designed
more for compatibility than for optimization. To some extent,
vertically integrated manufacturers are able to optimize their
drivelines. However, this is not widespread in the vocational vehicle
sector, resulting primarily, from the multi-stage manufacture process.
The agencies project transmission and driveline optimization will yield
a substantial proportion of vocational vehicle fuel efficiency and GHG
emissions reduction improvements for Phase 2. On average, we anticipate
that efficiency improvements of about five percent can be achieved from
optimization, or deep integration of drivelines. However, we are not
assigning a fixed level of improvement; rather we have developed a test
procedure, the powertrain test, for manufacturers to use to obtain
improvement factors representative of their systems. See Section V.E
and the draft RIA Chapter 3 for a discussion of this proposed test
procedure. Depending on the test cycle and level of integration, the
agencies believe improvement factors greater than ten percent above the
baseline vehicle performance could be achieved. To obtain such benefits
across more of the vocational vehicle fleet, the agencies believe there
is opportunity for manufacturers to form strategic partnerships and to
explore commercial pathways to deeper driveline integration. For
example, one partnership of an engine manufacturer and a transmission
manufacturer has led to development of driveline components that
deliver improved fuel efficiency based on optimization that could not
be realized without sharing of critical data.\276\
---------------------------------------------------------------------------

    \276\ See Cummins-Eaton partnership at http://smartadvantagepowertrain.com/
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    The agencies project other related transmission technologies would
be recognized over the powertrain test along with driveline
optimization. These include improved mechanical gear efficiency, more
sophisticated shift strategies, more aggressive torque converter
lockups, transmission friction reduction, and reduced parasitic losses,
as described in the 2009 TIAX report at 4.5.2. Each of these attributes
would be simulated in GEM using default values, unless the powertrain
test were utilized by the certifying manufacturer. The draft RIA
Chapter 4 explains each parameter that would be set as a fixed value in
GEM. The expected benefits of improved gear efficiency, shift logic,
and torque converter lockup are included in the total projected
effectiveness of optimized conventional transmissions using the
powertrain test.
    Transmission efficiency could also be improved in the time frame of
the proposed rules by changes in the architecture of conventional
transmissions. Most vocational vehicles currently use torque converter
automatic transmissions (AT), especially in Classes 2b-6. According to
the 2009 TIAX report, approximately 70 percent of Class 3-6 box and
bucket trucks use AT, and all refuse trucks, urban buses, and motor
coaches use AT.\277\ Automatic transmissions offer acceleration
benefits over drive cycles with frequent stops, which can enhance
productivity. However, with the diversity of vocational vehicles and
drive cycles, other kinds of transmission architectures can meet
customer needs, including automated manual transmissions (AMT) and even
some manual transmissions (MT).\278\
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    \277\ See TIAX 2009, Note 137, above.
    \278\ See http://www.truckinginfo.com/channel/equipment/article/story/2014/10/2015-medium-duty-trucks-the-vehicles-and-trends-to-look-for/page/3.aspx (downloaded November 2014).
---------------------------------------------------------------------------

    One type of architectural improvement the agencies project will be
developed by manufacturers of all transmission architectures is
increased number of gears. The benefit of adding

more gears varies depending on whether the gears are added in the range
where most operation occurs. The TIAX 2009 report projected that 8-
speed transmissions could incrementally reduce fuel consumption by 2 to
3 percent over a 6-speed automatic transmission, for Class 3-6 box and
bucket trucks, refuse haulers, and transit buses.\279\ Although the
agencies estimate the improvement could on average be about two percent
for the adding of two gears in the range where significant vehicle
operation occurs, we are not assigning a fixed improvement based solely
on number of transmission gears. Manufacturers would enter the number
of gears and gear ratios into GEM and the model would simulate the
efficiency benefit over the applicable test cycle. Because a public
version of proposed GEM is being released with these proposed rules,
stakeholders are free to use this tool to explore the effectiveness of
different numbers of gears and gear ratios over the proposed test
cycles. The agencies request comment on all aspects of the GEM tool,
including how it models transmissions and shifting strategies. More
details on GEM are available in the draft RIA Chapter 4.
---------------------------------------------------------------------------

    \279\ See TIAX 2009, Note 137, Table 4-48.
---------------------------------------------------------------------------

    Other architectural changes that the agencies project will offer
efficiency improvements include improved automated manual transmissions
(AMT) and introduction of dual clutch transmissions (DCT). Newer
versions of AMT are showing significant improvements in reliability,
such that the current generation of transmissions with this
architecture is more likely to retain resale value and win customer
acceptance than early models.\280\ The agencies believe AMT generally
compare favorably to manual transmissions in fuel efficiency, and while
the degree of improvement is highly driver-dependent, it can be two
percent or greater, depending on the drive cycle. See Section III for
additional discussion of AMT. The agencies are not assigning fixed
average performance levels to compare an AMT with a traditional
automatic transmission. Although the lack of a torque converter offers
AMT an efficiency advantage in one respect, the lag in power during
shifts is a disadvantage. For Phase 2, the agencies have developed
validated models of both AMT and AT, as described in the draft RIA
Chapter 4. Manufacturers installing AMT or AT would enter the relevant
inputs to GEM and the simulation would calculate the performance. Dual
clutch transmissions (DCT) designed for medium heavy-duty vocational
vehicles are already in production, and could reasonably be expected to
be adapted for other weight classes of vocational vehicles during the
time frame of Phase 2.\281\ Based on supplier conversations,
manufacturers intend to match varying DCT designs with the diverse
needs of the heavy-duty market. The agencies do not yet have a
validated DCT model in GEM, and we are not assigning a fixed
performance level for DCT, though we expect the per-vehicle fuel
efficiency improvement due to switching from automatic to DCT to be in
the range of three percent over the GEM vocational vehicle test cycles.
Selection of transmission architecture type (Manual, AMT, AT, DCT)
would be made by manufacturers at the time of certification, and GEM
would either use this input information to simulate that transmission
using algorithms as described in the draft RIA Chapter 4, or fixed
improvements may be assigned. The agencies are assigning fixed levels
of improvement that vary by test cycle in GEM for AMT when replacing a
manual, which for vocational vehicles would be in the HHD Regional
subcategory. If a manufacturer elected not to conduct powertrain
testing to obtain specific improvements for use of a DCT, GEM would
simulate a DCT as if it were an AMT, with no fixed assigned benefit.
The draft RIA at Chapter 2.9 describes the projected effectiveness of
each type of transmission improvement for each vocational vehicle test
cycle.
---------------------------------------------------------------------------

    \280\ See NACFE Confidence Report: Electronically Controlled
Transmissions, at http://www.truckingefficiency.org/powertrain/automated-manual-transmissions (January 2015). See also http://www.overdriveonline.com/auto-vs-manual-transmission-autos-finding-solid-ground-by-sharing-data-with-engines/ (accessed November 2014).
    \281\ See Eaton Announcement September 2014, available at http://www.ttnews.com/articles/lmtbase.aspx?storyid=2969&t=Eaton-Unveils-Medium-Duty-Procision-Transmission.
---------------------------------------------------------------------------

    Hybrid powertrain systems are included under transmission
technologies because, depending on the design and degree of
hybridization, they may either replace a conventional transmission or
be deeply integrated with a conventional transmission. Further, these
systems are often manufactured by companies that also manufacture
conventional transmissions.
    The agencies are including hybrid powertrains as a technology on
which some of the proposed vocational vehicle standards are predicated.
We project a variety of mild and strong hybrid systems, with a wide
range of effectiveness. Mild hybrid systems that offer an engine stop-
start feature are discussed below under workday idle reduction. For
hybrid powertrains, we are estimating a 22 to 25 percent fuel
efficiency improvement over the powertrain test, depending on the duty
cycle in GEM for the applicable subcategory. The agencies obtained
these estimates by projecting a 27 percent effectiveness over the ARB
Transient cycle, and zero percent over the constant-speed highway
cruise cycles. With the proposed cycle weightings, this calculates to a
25 percent improvement over the Urban cycle, and 22 percent over the
Multi-Purpose cycle. According to the NREL Final Evaluation of UPS
Diesel Hybrid-Electric Delivery Vans, the improvement of a hybrid over
a conventional diesel in gallons per ton-mile on a chassis dynamometer
over the NYC Composite test cycle was 28 percent.\282\ NREL
characterizes the NYC Composite cycle as more aggressive than most of
the observed field data points from the study, and may represent an
ideal hybrid cycle in terms of low average speed, high stops per mile,
and high kinetic intensity. NREL noted that most of the observed field
data points were reasonably represented by the HTUF4 cycle, over which
the chassis dynamometer results showed a 31 percent improvement in
gallons per ton-mile. In units of grams CO2 per mile, NREL
reported these test results as 22 percent improvement over the NYC
Composite cycle and 26 percent improvement over the HTUF4 cycle. Based
on these results, and the fact that any improvement from strong hybrids
in Phase 2 would not be simulated in GEM, but rather would be evaluated
using the powertrain test, the agencies deemed it reasonable to
estimate a conservative 27 percent effectiveness over the ARB Transient
in setting the stringency of the proposed standards.
---------------------------------------------------------------------------

    \282\ Lammert, M., Walkowivz, K., NREL, Eighteen-Month Final
Evaluation of UPS Second Generation Diesel Hybrid-Electric Delivery
Vans, September 2012, NREL/TP-5400-55658.
---------------------------------------------------------------------------

    The Phase 1 standards were not predicated on any adoption of hybrid
powertrains in the vocational vehicle sector. Because the first
implementation year of Phase 1 came just three years after
promulgation, there was insufficient lead time for development and
deployment of the technology.\283\ In addition, our proposed Phase 2

vocational vehicle GEM test cycles are expected to better recognize
hybrid technology effectiveness than the Phase 1 hybrid test cycle,
especially in the Urban subcategory. Further, our Phase 2 cost analysis
shows that hybrid systems designed for LHD and MHD vocational vehicles
would cost less than the costs we were projecting in Phase 1. The
agencies believe the Phase 2 rulemaking timeframes would offer
sufficient lead time to develop, demonstrate, and conduct reliability
testing for technologies that are still maturing, including these
hybrid technologies.
---------------------------------------------------------------------------

    \283\ In addition to concerns over adequacy of lead time, the
agencies described concerns over ``modest'' emission reductions. See
76 FR 57234. Even so, in Phase 1 the agencies adopted provisions for
hybrids to generate advanced technology credits.
---------------------------------------------------------------------------

    Several types of vocational vehicles are well suited for hybrid
powertrains, and are among the early adopters of this technology.
Vehicles such as utility or bucket trucks, delivery vehicles, refuse
haulers, and buses have operational usage patterns with either a
significant amount of stop-and-go activity or spend a large portion of
their operating hours idling the main engine to operate a PTO unit.
    The industry is currently developing many variations of hybrid
powertrain systems. There are a few hybrid systems in the market today
and several more under development. In addition, energy storage systems
are improving.\284\ Heavy-duty customers are getting used to these
systems with the number of demonstration products on the road. Even so,
some manufacturers may be uncertain how much investment to make in this
technology without clear signals about future market demand. A list of
hybrid manufacturers and their products intended for the vocational
market is provided in the draft RIA Chapter 2.9.
---------------------------------------------------------------------------

    \284\ Green Fleet Magazine, The Latest Developments in EV
Battery Technology, November 2013, available at http://www.greenfleetmagazine.com/article/story/2013/12/the-latest-developments-in-ev-battery-technology-grn/page/1.aspx.
---------------------------------------------------------------------------

    Some low cost products on the simple end of the hybrid spectrum are
available that minimize battery demand through the use of
ultracapacitors or only provide power assist at low speeds. Our
regulations define a hybrid system as one that has the capacity for
energy storage.\285\ In the light-duty GHG program a mild hybrid is
defined as including an integrated starter generator, a high-voltage
battery (above 12v), and a capacity to recover at least 15 percent of
the braking energy. In such systems some accessories are usually
electrified. Strong hybrids are typically referred to as those that
have larger energy recovery and storage capacity, defined at 65 percent
braking energy recovery in the light-duty GHG program. Although
integration of a strong hybrid system may enable installation of a
downsized engine in some cases, the agencies have not projected any
vocational engine downsizing for any hybrid systems as part of our
Phase 2 technology assessment. This is in part to be conservative in
our cost estimates, and in part because in some applications a smaller
engine may not be acceptable if it would risk that performance could be
sacrificed during some portion of a work day. Depending on the drive
cycle and units of measurement, strong hybrids developed to date have
seen fuel consumption and CO2 emissions reductions between
20 and 50 percent in the field.\286\
---------------------------------------------------------------------------

    \285\ EPA's and NHTSA's regulations define a hybrid vehicle as
one that ``includes energy storage features . . . in addition to an
internal combustion engine or other engine using consumable chemical
fuel. . . .'' at 40 CFR 1037.801 and 49 CFR 535.4.
    \286\ Van Amburg, Bill, CALSTART, Status Report: Alternative
Fuels and High-Efficiency Vehicles, Presentation to National
Association of Fleet Administrators (NAFA) 2014 Institute and Expo,
April 8, 2014.
---------------------------------------------------------------------------

    The agencies are working to reduce barriers related to hybrid
vehicle certification. In Phase 1, there is a significant test burden
associated with demonstrating the GHG and fuel efficiency performance
of vehicles with hybrid powertrain systems. Manufacturers must obtain a
conventional vehicle that is identical to the hybrid vehicle in every
way except the transmission, test both, and compare the results.\287\
In Phase 2, the agencies are proposing that manufacturers would conduct
powertrain testing on the hybrid system, and the results of that
testing would become inputs to GEM for simulation of the non-powertrain
features of the hybrid vehicle, removing a significant test burden.
---------------------------------------------------------------------------

    \287\ See test procedures at 40 CFR 1037.555.
---------------------------------------------------------------------------

    In discussions with manufacturers during the development of Phase
2, the agencies have learned that meeting the on-board diagnostic
requirements for criteria pollutant engine certification continues to
be a potential impediment to adoption of hybrid systems. See Section
XIV.A.1 for a discussion of regulatory changes proposed to reduce the
non-GHG certification burden for engines paired with hybrid powertrain
systems. The agencies have also received a letter from the California
Air Resources Board requesting consideration of supplemental
NOX testing of hybrids. The agencies request comment on the
Air Resources Board's letter and recommendations.\288\
---------------------------------------------------------------------------

    \288\ California Air Resources Board. Letter from Michael Carter
to Matthew Spears dated December 29, 2014. CARB Request for
Supplemental NOX Emission Check for Hybrid Vehicles.
Docket EPA-HA-OAR-2014-0827.
---------------------------------------------------------------------------

(ii) Axles
    The agencies are considering two axle technologies for the
vocational vehicle sector. The first is advanced low friction axle
lubricants. Under contract with NHTSA, SwRI tested improved driveline
lubrication and found measurable improvements by switching from current
mainstream products to newer formulations focusing on modified
viscometric effects.\289\ Synthetic lubricant formulations can offer
superior thermal and oxidative stability compared to petroleum or
mineral based lubricants. The agencies believe that a 0.5 percent
improvement in vocational vehicle efficiency (as for tractors) is
achievable through the application of low friction axle lubricants, and
have included that value as a fixed value in GEM. Beyond the use of
different lubricant formulations, some axle manufacturers are offering
products that achieve efficiency improvements by varying the
lubrication levels with vehicle speed, reducing churning losses. The
agencies request comment on whether we could accept these systems as
qualifying for a fixed GEM improvement value. If a manufacturer wishes
to demonstrate the benefit of a specific axle technology, an off-cycle
technology credit would be necessary. To support such an application,
manufacturers could conduct a rear axle efficiency test, as described
in the draft RIA Chapter 3.8. Proposed regulations for this test
procedure can be found at 40 CFR 1037.560. Our estimated axle
lubricating costs do not include operational costs such as refreshing
lubricants on a periodic basis. Based on supplier information, it is
likely that some advanced lubricants may have a longer drain interval
than traditional lubricants. We are estimating the axle lubricating
costs for HHD to be the same as for tractors since those vehicles
likewise typically have three axles. However, for LHD and MHD
vocational vehicles, we scaled down the cost of this technology to
reflect the presence of a single rear axle.
---------------------------------------------------------------------------

    \289\ Reinhart, T.E. (June 2015). Commercial Medium- and Heavy-
Duty Truck Fuel Efficiency Technology Study--Report #1. (Report No.
DOT HS 812 146). Washington, DC: National Highway Traffic Safety
Administration (the 2015 NHTSA Technology Study). For axle
improvements see T-270 Delivery Truck Vehicle Technology Results.
---------------------------------------------------------------------------

    The second axle technology the agencies are considering is a design
that enables one of the rear axles to disconnect or otherwise behave as
if it's a non-driven axle, on vehicles with two rear (drive) axles,
commonly referred to as a 6x2 configuration. The agencies have
considered two types of 6x2 configurations for vocational vehicles:

Those that are engaged full time on a vehicle, and those that may be
engaged only during some types of vehicle operation, such as only when
operating at highway cruise speeds. Some early versions of 6x2
technology offered by manufacturers were not accepted by vehicle
owners. When the second drive axle is no longer powered, traction may
be sacrificed in some cases. Vehicles with earlier versions of this
technology have seen reduced residual values in the secondary market.
Over the model years covered by the Phase 2 rules, the agencies expect
the market to offer significantly improved versions of this technology,
with traction control maintained at lower speeds and efficiency gains
at highway cruise speeds.\290\ Further information about this
technology is provided in the feasibility of the tractor standards,
Section III, as well as in draft RIA Chapter 2.4.
---------------------------------------------------------------------------

    \290\ NACFE, Confidence Findings on the Potential of 6x2 Axles,
available at http://nacfe.org/wp-content/uploads/2014/01/Trucking-Efficiency-6x2-Confidence-Report-FINAL-011314.pdf, January 2014
(downloaded November 2014).
---------------------------------------------------------------------------

    The efficiency benefit of a 6x2 axle configuration can be duty-
cycle dependent. In many instances, vocational vehicles need to operate
off-highway, such as at a construction site delivering materials or
dumping at a refuse collection facility. In these cases, vehicles with
two drive axles may need the full tractive benefit of both drive axles.
The part-time 6x2 axle technology is not expected to measurably improve
a vehicle's efficiency for vehicles whose normal duty cycle involves
performing significant off-highway work, but the agencies do expect
this technology to be recognized over a highway cruise cycle.
    Some vocational vehicles in the HHD Regional subcategory may see a
6x2 axle configuration as a reasonable option for improving fuel
efficiency. As in Phase 1, our vehicle simulation model assumes that
only HHD vehicles have two rear axles, so only these could be
recognized for adopting this technology. Further, the agencies don't
believe the Multipurpose and Urban subcategories include a significant
enough highway cycle weighting in the composite cycle for vehicles that
operate in this manner to experience a benefit from adopting this
technology. The agencies project this can achieve 2 percent benefit at
highway cruise; \291\ thus, we propose to assign a fixed value in GEM
for part-time 6x2 technology of 2.5 percent over the highway cruise
cycles, where the specific improvement would be calculated according to
the composite weighting of the applicable vocational vehicle test
cycle. We request comment on the best way to recognize this technology
in Phase 2, either through a GEM calculation or a fixed assigned value,
for vocational vehicles.
---------------------------------------------------------------------------

    \291\ See 2015 NHTSA Technology Study, Note 289, T-700 Class 8
Tractor-Trailer Vehicle Technology Results.
---------------------------------------------------------------------------

(iii) Lower Rolling Resistance Tires
    Tires are the second largest contributor to energy losses of
vocational vehicles, as found in the energy audit conducted by Argonne
National Lab.\292\ There is a wide range of rolling resistance of tires
used on vocational vehicles today. This is in part due to the fact that
the competitive pressure to improve rolling resistance of vocational
vehicle tires has been less than that found in the line haul tire
market. In addition, the drive cycles typical for these applications
often lead vocational vehicle buyers to value tire traction and
durability more heavily than rolling resistance. The agencies
acknowledge there can be tradeoffs when designing a tire for reduced
rolling resistance. These tradeoffs can include characteristics such as
wear resistance, cost and scuff resistance. However, based on input
from tire suppliers, the agencies expect that the LRR tires that will
be available in the Phase 2 timeframe will not compromise performance
parameters such as traction, handling, wear, retreadability, or
structural durability.
---------------------------------------------------------------------------

    \292\ See Argonne National Laboratory 2009 report, Note 275,
page 91.
---------------------------------------------------------------------------

    After the Phase 1 rules were promulgated, NHTSA and EPA conducted
supplemental tire testing. Other data that have become available to the
agencies since Phase 1 include pre-certification data provided to
manufacturers by tire suppliers in preparation for MY 2014 vehicle
certification.\293\ The agencies categorized the data by tire position
and vehicle application, so that we have a representation of the
variety of LRR vocational vehicle tires that are available in the
market for the drive position, steer and all-position tires, as well as
wide base singles in all positions. Based on our data set that includes
results from multiple laboratories, drive tires that are intended for
vocational vehicles have an average CRR of 7.8, and steer and all-
position tires that are intended for vocational vehicles have an
average CRR of 6.7. The results also indicate that there are a variety
of wide based single tires that are intended for vocational vehicles,
with an average CRR of 6.6. Each of these data sets shows several
models of commercial tires are available at levels of CRR ranging
generally from 20 percent worse than average to 20 percent better than
average. Further details are presented in the draft RIA Chapter 2.
---------------------------------------------------------------------------

    \293\ See memorandum dated May 2015 on Vocational Vehicle Tire
Rolling Resistance Test Data Evaluation.
---------------------------------------------------------------------------

    According to the 2015 NHTSA Technology Study, vocational vehicles
are likely to see the most benefits from reduced tire rolling
resistance when they are driving at 55 mph.\294\ This report also found
an influence of vehicle weight on the benefits of LRR tires. The study
found that both vocational vehicles tested had greater benefits of LRR
tires at 100 percent payload than when empty. Also, the T270 delivery
box truck that was 4,000 lbs heavier when fully loaded saw slightly
greater efficiency gains from LRR tires than the F650 flatbed tow truck
over the same cycles. At higher speeds, aerodynamic drag grows, which
reduces the rolling resistance share of total vehicle power demand. In
highly transient cycles, the power required to accelerate the vehicle
inertia overshadows the rolling resistance power demand. In simulation,
GEM represents vocational vehicles with fixed vehicle weights, payloads
and aerodynamic coefficients. Thus, the benefit of LRR tires will be
reflected in GEM differently for vehicles of different weight classes.
There will also be further differences arising from the different test
cycles. Based on preliminary simulations, it appears the vehicles in
GEM most likely to see the greatest fuel efficiency gains from use of
LRR tires are those in the MHD weight classes tested over the Regional
or Multipurpose duty cycles, where one percent efficiency improvement
could be achieved by reducing CRR by four to five percent. Those seeing
the least benefit from LRR tires would likely be Class 8 vehicles
tested over the Urban or Multipurpose cycles, where one percent
efficiency improvement could be achieved by reducing CRR by seven to
eight percent.
---------------------------------------------------------------------------

    \294\ See 2015 NHTSA Technology Study, Note 289, T-270 Delivery
Truck Vehicle Technology Results
---------------------------------------------------------------------------

    The agencies propose to continue the light truck (LT) tire CRR
adjustment factor that was adopted in Phase 1. See generally 76 FR
57172-57174. In Phase 1, the agencies developed this adjustment factor
by dividing the overall vocational test average CRR of 7.7 by the LT
vocational average CRR of 8.9. This yielded an adjustment factor of
0.87. After promulgation of the Phase 1 rules, the agencies conducted
additional tire CRR testing on a variety of LT tires, most of which
were designated as all-

position tires. In addition, manufacturers have submitted to the
agencies pre-certification data that include CRR values provided by
tire suppliers. For the small subset of newer test tires that were
designated as steer tires, the average CRR was 7.8 kg/ton. For the
subset of newer test tires that were designated as drive tires, the
average CRR was 8.6 kg/ton. However all-position tires had an average
CRR of 8.9 kg/ton.\295\ Therefore, for LT vocational vehicle tires, we
propose to continue allowing the measured CRR values to be multiplied
by a 0.87 adjustment factor before entering the values in the GEM for
compliance, because this additional testing has not revealed compelling
information that a change is needed. We request comment on whether the
adjustment factor should be retained, as well as data on which to base
a possible update of its numerical value.
---------------------------------------------------------------------------

    \295\ See tire memorandum, Note 293.
---------------------------------------------------------------------------

    As described above in V. B. (4) (c), the agencies are proposing to
continue the Phase 1 off-road and low speed exemptions in Phase 2, with
the proposed revision of discontinuing the option to qualify for this
exemption solely if the vehicle is fitted with tires that have a
maximum speed rating at or below 55 mph. The agencies welcome comments
on this revision.
(iv) Workday Idle Reduction
    The Phase 2 idle reduction technologies considered for vocational
vehicles are those that reduce workday idling, unlike the overnight
idling of combination tractors. There are many potential technologies.
The agencies in particular evaluated neutral idle and stop-start
technologies, and the proposed standards are predicated on projected
amounts of penetrations of these technologies, described in Section V.
C. (2) . While neutral idle is necessarily a transmission technology,
stop-start could range from an engine technology to one that would be
installed by a secondary manufacturer under a delegated assembly
agreement.
    The agencies are aware that for a vocational vehicle's engine to
turn off during workday driving conditions, there must be a reserve
source of energy to maintain functions such as power steering, cabin
heat, and transmission pressure, among others. Stop-start systems can
be viewed as having a place on the low-cost end of the hybridization
continuum. As described in Section V. C. (2) and in the draft RIA
Chapter 2.9, the agencies are including the cost of energy storage
sufficient to maintain critical onboard systems and restart the engine
as part of the cost of vocational vehicle stop-start packages. The
technologies to capture this energy could include a system of
photovoltaic cells on the roof of a box truck, or regenerative braking.
The technologies to store the captured energy could include a battery
or a hydraulic pressure bladder. More discussion of stop-start
technologies is found in the draft RIA Chapter 2.4.
    The agencies intend for the technologies that would qualify to be
recognized in GEM as stop-start to be broadly defined, including those
that may be installed at different stages in the manufacturing process.
The agencies request comment on an appropriate definition of stop-start
technologies for vocational vehicles.
    The agencies are also proposing a certification test cycle that
measures the amount of fuel saved and CO2 reduced by these
two primary types of idle reduction technologies: neutral idle and
stop-start. Vocational vehicles frequently also idle while cargo is
loaded or unloaded, and while operating a PTO such as compacting
garbage or operating a bucket. In these rules, the agencies are
proposing that the Regional duty cycle have ten percent idle, the
Multi-purpose cycle have 15 percent idle, and the Urban cycle have 20
percent idle. These estimates are based on publically available data
published by NREL.\296\ To bolster this information, EPA entered into
an interagency agreement with NREL to characterize workday idle among
vocational vehicles. One task of this agreement is to estimate the
nationally representative fraction of idle operation for vocational
vehicles for each proposed regulatory subcategory including a
distinction between idling while driving or stopping in gear, and
idling while parked. The preliminary range of total daily idle
operation per vehicle indicated by this work is about 18 percent to 33
percent when combining the data from all available vehicles. The
agencies request comment regarding the nature of vocational workday
idle operation, including how much of it is in traffic and how much is
while the vehicle is parked. Depending on comments and additional
information received during the comment period, it may be within the
agencies' discretion to adopt different final test cycles, or re-weight
the current test cycles, to better represent real world driving and
better reflect performance of the technology packages. An analysis of
possible vocational vehicle standards derived from alternate
characterizations of idle operation has been prepared by the agencies,
and is available for review in the public docket for this
rulemaking.\297\
---------------------------------------------------------------------------

    \296\ See NREL data at http://www.nrel.gov/vehiclesandfuels/fleettest/research_fleet_dna.html.
    \297\ See memorandum dated May 2015 on Analysis of Possible
Vocational Vehicle Standards Based on Alternative Idle Cycle
Weightings.
---------------------------------------------------------------------------

    Based on GEM simulations using the currently proposed vocational
vehicle test cycles, the agencies estimate neutral idle for automatic
transmissions to provide fuel efficiency improvements ranging from one
percent to nearly four percent, depending on the regulatory
subcategory. The agencies estimate stop-start to provide fuel
efficiency improvements ranging from 0.5 percent to nearly seven
percent, depending on the regulatory subcategory. Because of the higher
idle weighting factor in the Urban test cycle, vehicles certified in
these subcategories would derive the greatest benefit from applying
idle reduction technologies.
    Although the primary program would not simulate vocational vehicles
over a test cycle that includes PTO operation, the agencies are
proposing to continue, with revisions, the hybrid-PTO test option that
was in Phase 1. See 76 FR 57247 and 40 CFR 1037.525 (proposed to be
redesignated as 40 CFR 1037.540). Recall that we are proposing to
regulate vocational vehicles at the incomplete stage when a chassis
manufacturer may not know at the time of certification whether a PTO
will be installed or how the vehicle will be used. Based on stakeholder
input, chassis manufacturers are expected to know whether a vehicle's
transmission is PTO-enabled. However, that is very different from
knowing whether a PTO will actually be installed and how it will be
used. Chassis manufacturers may rarely know whether the PTO-enabled
vehicle will use this capability to maneuver a lift gate on a delivery
vehicle, to operate a utility boom, or merely to keep it as a reserve
item to add value in the secondary market. In cases where a
manufacturer can certify that a PTO with an idle-reduction technology
will be installed either by the chassis manufacturer or by a second
stage manufacturer, the hybrid-PTO test cycle may be utilized by the
certifying manufacturer to measure an improvement factor over the GEM
duty cycle that would otherwise apply to that vehicle. In addition, the
delegated assembly provisions would apply. See Section V.E for a
description of the delegated assembly provisions. See draft RIA Chapter
3 for a discussion of the proposed revisions to the PTO test cycle.

    The agencies have reason to believe there may be a NOX
co-benefit to stop-start idle reduction technologies, e-PTO, and
possibly also to neutral idle. For this to be true, the benefits of
reduced fuel consumption and retained aftertreatment temperature would
have to outweigh any extra emissions due to re-starts. In the draft RIA
Chapter 2.9, there is a more detailed discussion of the relationship
between idle reduction and NOX co-benefits. The agencies
request comments and relevant test data that can help inform this
issue.
(v) Weight Reduction
    The agencies believe there is opportunity for weight reduction in
some vocational vehicles. According to the 2009 TIAX report, there are
freight-efficiency benefits to reducing weight on vocational vehicles
that carry heavy cargo, and tax savings potentially available to
vocational vehicles that remain below excise tax weight thresholds.
This report also estimates that the cost effectiveness of weight
reduction over urban drive cycles is potentially greater than the cost
effectiveness of weight reduction for long haul tractors and trailers.
On a city duty cycle, 89 percent of the vehicle's road load is weight
dependent, compared to 38 percent on a steady-state 55 mph duty
cycle.\298\ The 2015 NHTSA Technology Study found that weight reduction
provides a greater fuel efficiency benefit for vehicles driving under
transient conditions than for those operating under constant speeds. In
simulation, the study found that the two Class 6 trucks improved fuel
efficiency by over two percent on the ARB transient cycle by removing
1,100 lbs. Further, SwRI observed that the improvements due to weight
reduction behaved linearly.\299\ The proposed menu of components
available for a vocational vehicle weight credit in GEM is presented in
Section V.E and in the draft RIA Chapter 2.9. It includes fewer options
than for tractors, but the agencies believe there are a number of
feasible material substitution choices at the chassis level, which
could add up to weight savings on the order of a few hundred lbs. The
agencies project that refuse trucks, construction vehicles, and weight-
limited regional delivery vehicles could reasonably apply material
substitution for weight reduction. We do not expect this to be broadly
applicable across many types of vocational vehicles. Based on the
assumed payload in GEM, and depending on the vocational vehicle
subcategory, the agencies believe a reduction of 200 lbs may offer a
fuel efficiency improvement of approximately 1 to 2 percent.
---------------------------------------------------------------------------

    \298\ Helms 2003 as referenced in TIAX 2009.
    \299\ See 2015 NHTSA Technology Study, Note 289, T-270 Delivery
Truck Vehicle Technology Results and Vehicle Performance in the F-
650 Truck.
---------------------------------------------------------------------------

    Without more specific data on which to base our assumptions, the
agencies are proposing to allocate 50 percent of any mass reduction to
increased payload, and 50 percent to reduce the chassis weight. We
considered the data on which the tractor weight allocation (1/3:2/3) is
based, but determined this would not be valid for vocational vehicles,
as the underlying data pertained only to long haul tractor-trailers.
The agencies propose that 50 percent of weight removed from vocational
vehicle chassis would be added back as additional payload in GEM. This
suggests an equal likelihood that a vehicle would be reducing weight
for benefits of being lighter, or reducing weight to carry more
payload. The agencies welcome data that could better inform the
fraction of weight reduced for vocational vehicles that is added back
as payload.
    The agencies request comment on whether the HD Phase 2 program
should recognize that weight reduction of rotating components provides
an enhanced fuel efficiency benefit over weight reduction on static
components. In theory, as components such as brake rotors, brake drums,
wheels, tires, crankshafts, camshafts, and piston assemblies become
lighter, the power consumption to rotate the masses would be directly
proportional to the mass decrease. Using physical properties of a
rotating component such as a wheel, it is relatively straightforward to
calculate an equivalent mass. However, we do not have enough
information to derive industry average values for equivalent mass, nor
have we evaluated the best way for GEM to account for this.
(vi) HFC Refrigerant From Cabin Air Conditioning (A/C) Systems
    Manufacturers can reduce direct A/C leakage emissions by utilizing
leak-tight components. EPA's proposed HFC direct emission leakage
standard would be independent of the CO2 vehicle standard.
Manufacturers could choose components from a menu of leak-reducing
technologies sufficient to comply with the standard, as opposed to
using a test to measure performance. See 76 FR 57194.
    In Phase 1, EPA adopted a HFC leakage standard to assure that high-
quality, low-leakage components are used in each air conditioning
system installed in HD pickup trucks, vans, and combination tractors
(see 40 CFR 1037.115). We did not adopt a HFC leakage standard in Phase
1 for systems installed in vocational vehicles. EPA is proposing in
Phase 2 to extend the HFC leakage standard that exists due to Phase 1
requirements to all vocational vehicles. Beginning in the 2021 model
year, EPA proposes that vocational vehicle air conditioning systems
with a refrigerant capacity of greater than 733 grams meet a leakage
rate of 1.50 percent leakage per year and systems with a refrigerant
capacity of 733 grams or lower meet a leakage standard of 11.0 grams
per year. EPA believes this proposed approach of having a leak rate
standard for lower capacity systems and a percent leakage per year
standard for higher capacity systems would result in reduced
refrigerant emissions from all air conditioning systems, while still
allowing manufacturers the ability to produce low-leak, lower capacity
systems in vehicles which require them.
    EPA believes that reducing A/C system leakage is both highly cost-
effective and technologically feasible. The availability of low leakage
components is being driven by the air conditioning program in the
light-duty GHG rule which began in the 2012 model year and the HD Phase
1 rule that began in the 2014 model year. The cooperative industry and
government Improved Mobile Air Conditioning program has demonstrated
that new-vehicle leakage emissions can be reduced by 50 percent by
reducing the number and improving the quality of the components,
fittings, seals, and hoses of the A/C system.\300\ All of these
technologies are already in commercial use and exist on some of today's
systems, and EPA does not anticipate any significant improvements in
sealing technologies for model years beyond 2021. However, EPA has
recognized some manufacturers utilize an improved manufacturing process
for air conditioning systems, where a helium leak test is performed on
100 percent of all o-ring fittings and connections after final
assembly. By leak testing each fitting, the manufacturer or supplier is
verifying the o-ring is not damaged during assembly (which is the
primary source of leakage from o-ring fittings), and when calculating
the yearly leak rate for a system, EPA will allow a relative emission
value equivalent to a `seal washer' can be used in place of the value
normally used for an o-ring fitting, when 100 percent helium leak
testing is performed on those fittings. The agencies request comment on
other

possible improvements in the design of air conditioning systems that
EPA could recognize for the purposes of compliance with this proposed
standard. For example, should the agency recognize electrified
compressors as having a zero leak rate, and should we allow vehicles
fitted with electrified compressors to use a simplified version of the
compliance reporting form? Please see Section I.F.1 (b) of this
preamble for a description of proposed program-wide revisions to EPA's
HFC leakage standards that would address air conditioning systems
designed for alternative refrigerants.
---------------------------------------------------------------------------

    \300\ Team 1-Refrigerant Leakage Reduction: Final Report to
Sponsors, SAE, 2007.
---------------------------------------------------------------------------

    The HFC control costs presented in the draft RIA Chapter 2.9 and
2.12 are applied to all heavy-duty vocational vehicles. EPA views these
costs as minimal and the reductions of potent GHGs to be easily
feasible and reasonable in the lead times provided by the proposed
rules.
(b) Engine Technologies Considered in Vehicle Standard-Setting
    Section II explains the technical basis for the agencies' proposed
separate engine standards. The agencies are not proposing to predicate
the vocational vehicle standards on different diesel engine technology
packages than those presumed for compliance with the separate diesel
engine standards. However, for the proposed MY 2027 vocational vehicle
standards, the agencies are predicating the SI-powered vocational
vehicle standards on a gasoline engine technology package that includes
additional friction reduction beyond that presumed for compliance with
the MY 2016 gasoline engine standard. Chapter 2 of the draft RIA
provides more details on each of the technologies that can be applied
to both gasoline and diesel engines.
    The vehicle-level standards would vary depending on whether the
engines powering those vehicles are compression-ignition or spark-
ignition.\301\ In Phase 1, this was not the case because GEM used a
default engine that was the same for every vehicle configuration,
regardless of the actual engine being installed. As described above in
Section II, the Phase 2 vehicle certification tool, GEM, would require
manufacturers to enter specific engine performance data, where
emissions and fuel consumption profiles would differ significantly
depending on the engine's architecture.\302\
---------------------------------------------------------------------------

    \301\ Specifically, EPA is proposing CO2,
N2O, and CH4 emission standards for new heavy-
duty engines over an EPA specified useful life period (See Section
II).
    \302\ See Section II.D.5 for an explanation of which engine
architecture would need to meet which standard.
---------------------------------------------------------------------------

    As explained in Section II.A.2, engines would continue to be
certified over the FTP test cycle. The FTP test cycle that is
applicable for bare vocational engines is very different than the
proposed test cycles for vocational vehicles in GEM. The FTP is a very
demanding transient cycle that exercises the engine over its full range
of capabilities. In contrast, the cycles evaluated by GEM measure
emissions over more frequently used engine operating ranges. The ARB
Transient vehicle cycle represents city driving, and the highway cruise
cycles measure engine operation that is closer to steady state. Each of
these cycles is described in the draft RIA Chapter 3. A consequence of
recognizing engine performance at the vehicle level would be that
further engine improvements (i.e. improvements measureable by duty
cycles that more precisely represent driving patterns for specific
subcategories of vocational vehicles) could be evaluated as possible
components of a technical basis for a vocational vehicle standard.\303\
For this reason, the agencies considered whether any different engine
technologies should be included in the feasibility analysis for the
vehicle standards (and potentially, in the proposed standard
stringency).
---------------------------------------------------------------------------

    \303\ As noted in II.B.2 above, manufacturers also have greater
flexibility to meet a vehicle standard if engine improvements can be
evaluated as part of compliance testing.
---------------------------------------------------------------------------

    One CI engine technology that might be recognized over a vehicle
highway cruise cycle would be waste heat recovery (WHR). However, the
agencies do not consider this to be a feasible technology for
vocational engines. As described in Section II of this preamble and
Chapter 2.3 of the draft RIA, there currently are no commercially
available WHR systems for diesel engines, although most engine
manufacturers are exploring this technology. While it would be possible
to capture excess heat from a vocational engine operating at highway
speeds, many vocational vehicles spend insufficient time at highway
speeds to generate enough excess heat to make this technology
worthwhile. As explained in Section II.D, the agencies are projecting a
very small adoption rate of WHR even in the tractor engine market.
Because the research is currently being conducted to apply this
technology for tractors, it is logical that future research may reveal
ways to adapt this technology for those vocational engines that are
intended for on-highway applications. The agencies do not believe this
technology will be developed to the point of commercial readiness for
vocational vehicles in the time frame of these proposed rules.
    The agencies assessed three SI engine technologies for possible
inclusion in the vocational vehicle technology packages: cylinder
deactivation, variable valve timing, and advanced friction reduction.
These might be recognized over the proposed vocational vehicle test
cycles in GEM through use of the proposed engine mapping procedures. To
the extent either cylinder deactivation or variable valve timing would
be adopted for complete heavy-duty pickups and vans, they would be
recognized over the complete chassis test specified for that segment
and possibly over the GEM highway cruise cycles, however the aggressive
bare engine FTP test is unlikely to put the engine into operating modes
that activate either of those technologies. Based on stakeholder input,
the agencies project that the SI engines certified over the FTP and
fitted into vocational vehicles would most likely be designed as
overhead valve engines, for which the only kind of VVT available is
dual cam phasing.\304\ Dual cam phasing is already included at 100
percent adoption rate in the feasibility and stringency of the MY 2016
bare engine standard. If manufacturers choose to fit vocational
vehicles with coaxial camshaft SI engines, additional VVT options would
be feasible and could be recognized over the vocational vehicle test
cycles. Based on stakeholder input, the agencies project that some SI
engines certified over the FTP and fitted into vocational vehicles may
be designed with cylinder deactivation by MY 2021. However, the
agencies do not have enough information at this time to quantify the
potential fuel efficiency improvements over the vocational vehicle test
cycles for engines with cylinder deactivation or various designs
implementing VVT. Therefore we are not proposing to predicate the SI-
powered vocational vehicle standards on use of these technologies.
---------------------------------------------------------------------------

    \304\ See preamble Section VI.C.5.(a) under Coupled Cam Phasing.
---------------------------------------------------------------------------

    In Section II.D, the agencies explain why we are not proposing a
more stringent separate SI vocational engine standard in Phase 2 based
on additional engine technologies beyond those assumed for the Phase 1
MY 2016 standard. The agencies are instead proposing to include
adoption and performance of advanced engine friction reduction
technology as a basis for the

proposed SI-powered vocational vehicle standards. Based on Volpe model
results presented in preamble Section VI, the agencies project that
manufacturers of some SI engines for complete HD pickups would apply
advanced friction reduction. Level 2 engine friction reduction is
listed in Table VI-3, and costs are presented in the draft RIA Chapter
2.12. We expect some engines with this technology would be engine-
certified and sold for use in vocational vehicles. We are projecting an
overall effectiveness of 0.6 percent improvement over the GEM cycles
for this technology, calculated using a per-vehicle effectiveness of
1.1 percent and a vocational vehicle adoption rate of 56 percent. We
request comment on the merits of setting a SI-based vocational vehicle
standard predicated on adoption of SI engine technologies.
(c) Technologies the Agencies Assessed but Did Not Use in Standard-
Setting
(i) Aerodynamics
    The Argonne National lab work shows that aerodynamics has less of
an impact on vocational vehicle energy losses than do engines or
tires.\305\ Further, when a vehicle spends significant time at slower
speeds, the disbenefit of the added weight of the aero devices
diminishes the benefit obtained when driving at high speeds. In
addition, the aerodynamic performance of a complete vehicle is
significantly influenced by the body of the vehicle. As noted above,
the agencies are not proposing to regulate body builders for the
reasons discussed in Phase 1.
---------------------------------------------------------------------------

    \305\ See Argonne National Laboratory 2009 report, Note 275,
above.
---------------------------------------------------------------------------

    The NAS 2010 report estimated a one percent fuel efficiency
improvement could be achieved from a full aerodynamic package on a box
truck with an average speed of 30 mph.\306\ Both from the NAS 2010
report and from experiences of EPA's SmartWay team, the agencies expect
the potential benefits of aerodynamics at an average speed of 60 mph
would be diminished by 50 percent or more when average speeds are
closer to 40 mph. The proposed Regional composite duty cycle in GEM for
vocational vehicles (the test cycle with the most highway weighting)
has a weighted average speed of 39 mph.
---------------------------------------------------------------------------

    \306\ See Table 5-10 of the NAS 2010 report, Note 136.
---------------------------------------------------------------------------

    The 2015 NHTDA Technology Study simulated a Class 6 box truck with
a coefficient of aerodynamic drag that had been improved by 15 percent.
Over transient test cycles, this produced a one percent fuel efficiency
benefit, though this produced results of approximately seven percent
improvement over the 55 mph and eight percent over the 65 mph cycle.
SwRI conducted coastdown testing to determine the baseline
CDA of the truck, of 5.0.\307\ However, it is unknown what
aerodynamic technologies could be applied to yield a 15 percent
improvement in CDA. Using these simulation results and the
proposed Regional cycle weightings of 22 percent at 65 mph and 28
percent at 55 mph, the agencies estimate the fuel efficiency benefit of
improving the CdA of a Class 6 box truck by 15 percent could be
approximately four percent. This assumes no penalty for carrying the
weight of the aerodynamic devices while operating under transient
driving conditions.
---------------------------------------------------------------------------

    \307\ See 2015 NHTSA Technology Study, Note 289, Appendix C.
---------------------------------------------------------------------------

    Because we do not have information on specific technologies that
could be applied to vocational vehicles to yield a 15 percent
improvement in CdA, or their costs, we are not basing any of the
proposed standards for vocational vehicles on aerodynamic improvements.
Nonetheless, we are working with CARB to incorporate into GEM some data
from testing that is being conducted by CARB through NREL. A test plan
is underway to assess the fuel efficiency benefit of three different
devices to improve the aerodynamic performance of a Class 6 box truck
and one device on a Class 4 box truck. The agencies request comment on
allowing a manufacturer to obtain an improved GEM result by certifying
that a final vehicle configuration will closely match one of the
configurations on which this testing was conducted, where the
improvement would be based on installation of specific aerodynamic
devices for which we have pre-defined effectiveness through this
testing program. The amount of improvement would be set by EPA and
NHTSA based on NREL's test results. This credit provision would apply
only to vocational vehicles certified over the Regional duty cycle.
Manufacturers wishing to receive credit for other aerodynamic
technologies or on other vehicle configurations would be able to seek
credit for it as an off-cycle technology. See Section V.E, for a
description of regulatory flexibilities such as off-cycle technology
credits.
    A description of vehicles and aerodynamic technologies that could
be eligible for this option, as well as a description of the testing
conducted to obtain the assigned GEM improvements due to these
technologies, can be found in a memorandum to the docket.\308\ The
agencies seek comment on this potential approach to providing credits
for aerodynamic aids to vocational box trucks.
---------------------------------------------------------------------------

    \308\ See May 2015 memorandum to the docket titled Vocational
Vehicle Aerodynamic Testing Program.
---------------------------------------------------------------------------

(ii) Full Electric Trucks
    Some heavy-duty vehicles can be powered exclusively by electric
motors. Electric motors are efficient and able to produce high torque,
giving e-trucks strong driving characteristics, particularly in stop-
and-go or urban driving situations, and are well-suited for moving
heavy loads. Electric motors also offer the ability to operate with
very low noise, an advantage in certain applications. Currently, e-
trucks have some disadvantages over conventional vehicles, primarily in
cost, weight and range. Components are relatively expensive, and
storing electricity using currently available technology is expensive,
bulky, and heavy.
    The West Coast Collaborative, a public-private partnership, has
estimated the incremental costs for electric Class 3-6 trucks in the
Los Angeles, CA, area.\309\ Compared to a conventional diesel, the WCC
estimates a BEV system would cost between $70,000 and $90,000 more than
a conventional diesel system. The CalHEAT Technology Roadmap includes
an estimate that the incremental cost for a fully-electric medium- or
heavy- duty vehicle would be between $50,000 and $100,000. This roadmap
report also presents several actions that must be taken by
manufacturers and others, before heavy-duty e-trucks can reach what
they call Stage 3 Deployment.\310\
---------------------------------------------------------------------------

    \309\ See http://westcoastcollaborative.org/files/sector-fleets/WCC-LA-BEVBusinessCase2011-08-15.pdf.
    \310\ Silver, Fred, and Brotherton, Tom. (CalHEAT) Research and
Market Transformation Roadmap to 2020 for Medium- and Heavy-Duty
Trucks. California Energy Commission, June 2013.
---------------------------------------------------------------------------

    Early adopters of electric drivetrain technology are medium-heavy-
duty vocational vehicles that are not weight-limited and have drive
cycles where they don't need to go far from a central garage. Examples
include Frito-Lay. CalHEAT has published results of a comprehensive
performance evaluation of three battery electric truck models using
information and data from in-use data collection, on road testing and
chassis dynamometer testing.\311\
---------------------------------------------------------------------------

    \311\ Gallo, Jean-Baptiste, and Jasna Tomic (CalHEAT). 2013.
Battery Electric Parcel Delivery Truck Testing and Demonstration.
California Energy Commission.

---------------------------------------------------------------------------

    Given the high costs and the developing nature of this technology,
the agencies do not project fully electric vocational vehicles to be
widely commercially available in the time frame of the proposed rules.
For this reason, the agencies have not based the proposed Phase 2
standards on adoption of full-electric vocational vehicles. To the
extent this technology is able to be brought to market in the time
frame of the Phase 2 program, there is currently a certification path
for these chassis from Phase 1, as described in Section V.E and in
EPA's regulations at 40 CFR 1037.150 and NHTSA's regulations at 49 CFR
535.8.
(iii) Electrified Accessories
    Accessories that are traditionally gear- or belt-driven by a
vehicle's engine can be optimized and/or converted to electric power.
Examples include the engine water pump, oil pump, fuel injection pump,
air compressor, power-steering pump, cooling fans, and the vehicle's
air-conditioning system. Optimization and improved pressure regulation
may significantly reduce the parasitic load of the water, air and fuel
pumps. Electrification may result in a reduction in power demand,
because electrically-powered accessories (such as the air compressor or
power steering) operate only when needed if they are electrically
powered, but they impose a parasitic demand all the time if they are
engine-driven. In other cases, such as cooling fans or an engine's
water pump, electric power allows the accessory to run at speeds
independent of engine speed, which can reduce power consumption.
Electrification of accessories can individually improve fuel
consumption, regardless of whether the drivetrain is a strong hybrid.
The TIAX study used 2 to 4 percent fuel consumption improvement for
accessory electrification, with the understanding that electrification
of accessories will have more effect in short haul/urban applications
and less benefit in line-haul applications.\312\
---------------------------------------------------------------------------

    \312\ TIAX 2009, Note 137, pp. 3-5.
---------------------------------------------------------------------------

    Electric power steering (EPS) or Electrohydraulic power steering
(EHPS) provides a potential reduction in CO2 emissions and fuel
consumption over hydraulic power steering because of reduced overall
accessory loads. This eliminates the parasitic losses associated with
belt-driven power steering pumps which consistently draw load from the
engine to pump hydraulic fluid through the steering actuation systems
even when the wheels are not being turned. EPS is an enabler for all
vehicle hybridization technologies since it provides power steering
when the engine is off. EPS is feasible for most vehicles with a
standard 12V system. Some heavier vehicles may require a higher voltage
system which may add cost and complexity.
    The agencies are projecting that some electrified accessories will
be necessary as part of the development of stop-start idle reduction
systems for vocational vehicles. However, the agencies have not
developed a pre-defined credit-generating option for manufacturers to
directly receive credit in GEM for electrified accessories on
vocational vehicles. Manufacturers wishing to conduct independent
testing may apply for off-cycle credits derived from electrified
accessories.
(iv) E-PTO
    There are products available today that can provide auxiliary
power, usually electric, to a vehicle that needs to work in PTO mode
for an extended time, to avoid idling the main engine. There are
different designs of electrified PTO systems on the market today. Some
designs have auxiliary power sources, typically batteries, with
sufficient energy storage to power an onboard tool or device for a
short period of time, and are intended to be recharged during the
workday by operating the main engine, either while driving between work
sites, or by idling the engine until a sufficient state of charge is
reached that the engine may shut off. Other designs have sufficient
energy storage to power an onboard tool or device for many hours, and
are intended to be recharged as a plug-in hybrid at a home garage. The
agencies are proposing to continue the hybrid-PTO test option that was
available in Phase 1, with a few revisions. See the proposed
regulations at 40 CFR 1037.540. The current test procedure is a charge-
sustaining procedure, meaning the test is not complete until the energy
storage system is depleted and brought back to its original state of
charge. The agencies request comment and data relating to the
population and energy storage capacity of plug-in e-PTO systems, for
which a charge-depleting test cycle may be more appropriate. For the
reasons described above in Section V.C.1.a.iv, the agencies are not
basing the proposed vocational vehicle standards on use of electrified
PTO or hybrid PTO technology. Manufacturers wishing to conduct testing
as specified may apply for off-cycle credits derived from e-PTO or
hybrid PTO technologies.
(2) Projected Vehicle Technology Package Effectiveness and Cost
(a) Baseline Vocational Engine and Vehicle Performance
    The proposed baseline vocational vehicle configurations for each of
the nine proposed regulatory subcategories are described in draft RIA
Chapter 2.9 and Chapter 4.4. The agencies propose to set the baseline
rolling resistance coefficient for the 2017 vocational vehicle fleet at
7.7 kg/metric ton, which assumes 100 percent of tires meet the Phase 1
standard.
    In the agencies' proposed baseline configurations, we include
torque converter automatics with five forward gears in eight of the
nine subcategories. In the Regional HHD subcategory, the baseline
includes a manual transmission with ten forward gears. No additional
vehicle-level efficiency-improving technology is included in the
baseline vehicles, nor in the agencies' analyses for the no-action
reference case. Specifically, we have assumed zero adoption rates for
other types of transmissions, increased numbers of gears, idle
reduction, and technologies other than Phase 1 compliant LRR tires in
both the nominally flat baseline and the dynamic baseline reference
cases. Technology adoption rates for Alternative 1a (nominally flat
baseline) can be found in the draft RIA Chapter 2.12. Chapter 2.12.8
presents the adoption rates for tires on vocational vehicles with
different levels of rolling resistance, including the 100 percent
adoption rate of tires with Level 1 CRR in the reference case and in
model years preceding Phase 2. In this manner, we have defined a
reference vocational vehicle fleet that meets the Phase 1 standards and
includes reasonable representations of vocational vehicle technology
and configurations. Details of the vehicle configurations, including
reasons why they are reasonably included as baseline technologies, are
discussed in the draft RIA Chapter 2.9.
    The agencies note that the baseline performance derived for the
proposed rules varies between regulatory subcategories--as noted above,
this is the reason the agencies are proposing the further
subcategories. The range of performance at baseline is due to the range
of attributes and modeling parameters, such as transmission
characteristics, final drive ratio, and vehicle weight, which were
selected to represent a range of performance across this diverse
segment. The agencies request comment on whether the proposed
configurations adequately represent a reasonable range of vocational
chassis configurations likely

to be manufactured in the implementation years of the Phase 2 program.
We especially are interested in comments regarding the following
driveline parameters: Transmission gear ratios, axle ratios, and tire
radii.
    The baseline engine fuel consumption represents improvements beyond
currently available engines to achieve the efficiency of what the
agencies believe would be a 2017 model year diesel engine, as described
in the draft RIA Chapter 2. Using the values for compression-ignition
engines, the baseline performance of vocational vehicles is shown in
Table V-11.
    Different types of diesel engines are used in vocational vehicles,
depending on the application. They fall into the categories of Light,
Medium, and Heavy Heavy-duty Diesel engines. The Light Heavy-duty
Diesel engines typically range between 4.7 and 6.7 liters displacement.
The Medium Heavy-duty Diesel engines typically have some overlap in
displacement with the Light Heavy-duty Diesel engines and range between
6.7 and 9.3 liters. The Heavy Heavy-duty Diesel engines typically are
represented by engines between 10.8 and 16 liters. Because of these
differences, the GEM simulation of baseline vocational CI engines
includes four engines--one for LHD, one for MHD, and two for HHD.
Detailed descriptions can be seen in Chapter 4 of the draft RIA. These
four engine models have been employed in setting the vocational vehicle
baselines, as described in the draft RIA Chapter 2.9.

                       Table V-11--Baseline Vocational Vehicle Performance With CI Engines
----------------------------------------------------------------------------------------------------------------
                                                                   Light heavy-
                           Duty cycle                             duty class 2b-   Medium heavy-   Heavy heavy-
                                                                         5        duty class 6-7   duty class 8
----------------------------------------------------------------------------------------------------------------
                            Baseline Emissions Performance in CO[bdi2] gram/ton-mile
----------------------------------------------------------------------------------------------------------------
Urban...........................................................             316             201             212
Multi-Purpose...................................................             325             203             214
Regional........................................................             339             199             203
----------------------------------------------------------------------------------------------------------------
                        Baseline Fuel Efficiency Performance in gallon per 1,000 ton-mile
----------------------------------------------------------------------------------------------------------------
Urban...........................................................         31.0413         19.7446         20.8251
Multi-Purpose...................................................         31.9253         19.9411         21.0216
Regional........................................................         33.3006         19.5481         19.9411
----------------------------------------------------------------------------------------------------------------

    The agencies intend to develop a model in GEM of a MY 2016-
compliant gasoline engine, but we have been unable to obtain sufficient
information to complete this process. The agencies request comments on
the process for mapping gasoline engines for simulation purposes, as
well as information about the power rating and displacement that should
be considered as a baseline SI engine for vocational vehicle standard-
setting purposes. In lieu of a SI engine map, the agencies have applied
a correction factor to the GEM CI vocational simulation results, to
approximate the baseline performance of a SI-powered vocational
vehicle. The SI-powered vocational vehicle baseline performance shown
in Table V-12 was calculated from applying an adjustment factor to the
respective CI-powered vocational vehicle baseline values. This CI to SI
baseline adjustment factor is derived from the Phase 1 HD pickup and
van stringency curves, as described in the draft RIA Chapter 2.9.1. The
correction factor approach is not the agencies' preferred approach, as
it has many drawbacks. One key drawback with this approach is that it
does not account for the fact that SI engines operate very differently
than CI engines at idle. Our current model includes information on CI
engine idle performance, and assumes transmissions and torque
converters appropriate for CI engines. We expect these driveline
parameters would be very different for SI powered vehicles, which would
affect performance over all the GEM duty cycles.
    The baseline performance levels for HHD vocational vehicles powered
by SI engines were derived using the same procedures described above
for the MHD and LHD vehicles, adjusting the performance of the HHD CI
powered vocational vehicles by the same degree as for the other
vehicles. However, we expect that any gasoline Class 8 vocational
vehicle would be powered by a MHD SI engine, as there are no HHD
gasoline engines on the market. Further, we expect that if we were to
develop an engine map for use in simulating heavier SI vocational
vehicles in GEM, we could establish a more representative baseline
performance level by calculating the work done by the MHD engine to
move the heavier vehicle over the test cycles. The agencies request
comments on the merits of developing separate baseline levels and
numerical standards for HHD vocational vehicles powered by SI engines,
including any benefits that could be obtained by addressing this
unlikely occurrence and other ways in which the agencies could avoid
the instance of an orphaned SI vocational vehicle. Commenters who favor
separate numerical standards are encouraged to submit information
related to appropriate default vehicle characteristics such as weight
and payload. Depending on comments, the agencies could choose to
require all Class 8 vocational vehicles to certify to the standards for
CI powered HHD vocational vehicles, or we could require SI powered
Class 8 vocational vehicles to certify to the MHD standards for SI
vocational vehicles.

                       Table V-12--Baseline Vocational Vehicle Performance With SI Engines
----------------------------------------------------------------------------------------------------------------
                                                     Light heavy-duty    Medium heavy-duty     Heavy heavy-duty
                    Duty cycle                          Class 2b-5           Class 6-7             Class 8
----------------------------------------------------------------------------------------------------------------
                            Baseline Emissions Performance in CO[bdi2] gram/ton-mile
----------------------------------------------------------------------------------------------------------------
Urban............................................                  334                  213                  224

Multi-Purpose....................................                  344                  215                  226
Regional.........................................                  358                  211                  214
----------------------------------------------------------------------------------------------------------------
                        Baseline Fuel Efficiency Performance in gallon per 1,000 ton-mile
----------------------------------------------------------------------------------------------------------------
Urban............................................              37.5830              23.9676              25.2054
Multi-Purpose....................................              38.7082              24.1926              25.4304
Regional.........................................              40.2836              23.7425              24.0801
----------------------------------------------------------------------------------------------------------------

(b) Technology Packages for Derivation of Proposed Standards
    Prior to developing the numerical values for the proposed
standards, the agencies projected the mix of new technologies and
technology improvements that would be feasible within the proposed lead
time. We note that for some technologies, the adoption rates and
effectiveness may be very similar across subcategories. However, for
other technologies, either the adoption rate, effectiveness, or both
differ across subcategories. The standards being proposed reflect the
technology projected for each service class. Where a technology
performs differently over different test cycles, these differences are
reflected to some extent in the derivation of the stringency of the
proposed standard. However, the proposed standard stringency does
reflect, to some extent, the ability of manufacturers to utilize
credits. For example, we project that hybrid vehicles would generally
be certified in the Urban subcategory and would generate emission
credits that would most likely be used in the other subcategories
within the weight class group.\313\
---------------------------------------------------------------------------

    \313\ See averaging sets at 40 CFR 1037.740.
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    As part of the derivation of the numerical standards, we performed
a benchmarking analysis to inform our development of standards that
would have roughly equivalent stringency among the duty-cycle-based
subcategories within each weight class group. To do this, the agencies
assessed the performance of broadly applicable technologies, such as
low rolling resistance tires, on each of the selected baseline vehicles
over each of the duty cycles. We then evaluated how much improvement
could be achieved over the various duty cycles for a vehicle that
incorporated all the broadly applicable technologies, but which did not
include a hybrid powertrain. We simulated neutral idle for benchmarked
vehicles for MY 2021 and MY 2024, and simulated stop-start idle
reduction on the benchmarked MY 2027 vehicles. From this, we learned
that a vehicle with neutral idle and a deeply integrated conventional
powertrain, with moderately low rolling resistance tires and some
weight reduction could easily meet the proposed standards in the early
implementation years of the program, in any weight class or duty cycle.
We also learned how the effectiveness of tire rolling resistance and
weight reduction vary in GEM (i.e. and therefore likely in actual
operation) across the different subcategories. We also found that a
vehicle with a deeply integrated conventional powertrain, tires with
even lower CRR, some weight reduction, and stop-start idle reduction
could achieve the MY 2027 proposed standards. However, our technology
feasibility does not presume that 100 percent of vocational vehicles
can reasonably apply deep powertrain integration, nor do we project 100
percent adoption of LRR tires or weight reduction.
    The technologies assumed for the benchmarked vehicles are
summarized in Table V-13, Table V-14, and Table V-15. Note that the
agencies are not projecting that these are the vehicles that would
actually be produced. Rather, these theoretical vehicles are being
evaluated to compare the relative stringency of the standards for each
subcategory.

                       Table V-13--GEM Inputs for Benchmarked MY 2021 Vocational Vehicles
----------------------------------------------------------------------------------------------------------------
              Class 2b-5                             Class 6-7                              Class 8
----------------------------------------------------------------------------------------------------------------
                Multi-                                 Multi-                               Multi-
   Urban       purpose      Regional      Urban       purpose      Regional      Urban      purpose    Regional
----------------------------------------------------------------------------------------------------------------
                                                  Transmission
----------------------------------------------------------------------------------------------------------------
                  100% Deep Transmission Integration for 7% Urban, 6% Multipurpose, 5% Regional
----------------------------------------------------------------------------------------------------------------
     5s AT        5s AT        5s AT        5s AT        5s AT        5s AT       5s AT       5s AT     10s AMT
----------------------------------------------------------------------------------------------------------------

                                                  CI Engine \a\
----------------------------------------------------------------------------------------------------------------
      2021 MY 7L, 22021 MY 7L, 270 hp Engine
                2021 MY 11L, 345 hp    2021 MY 15L
                      Engine                455hp
                                           Engine
----------------------------------------------------------------------------------------------------------------
                                       100% Idle Reduction = Neutral Idle
----------------------------------------------------------------------------------------------------------------
                                      100% improved axle lubrication: 0.5%
----------------------------------------------------------------------------------------------------------------
                                   100% Steer Tires with CRR 6.9 kg/metric ton
----------------------------------------------------------------------------------------------------------------
                                   100% Drive Tires with CRR 7.3 kg/metric ton
----------------------------------------------------------------------------------------------------------------
                                             Weight Reduction 200 lb
----------------------------------------------------------------------------------------------------------------
Note:
\a\ SI engines were not simulated in GEM.

                       Table V-14--GEM Inputs for Benchmarked MY 2024 Vocational Vehicles
----------------------------------------------------------------------------------------------------------------
              Class 2b-5                             Class 6-7                              Class 8
----------------------------------------------------------------------------------------------------------------
                Multi-                                 Multi-                               Multi-
   Urban       purpose      Regional      Urban       purpose      Regional      Urban      purpose    Regional
----------------------------------------------------------------------------------------------------------------
                                                  Transmission
----------------------------------------------------------------------------------------------------------------
                  100% Deep Transmission Integration for 7% Urban, 6% Multipurpose, 5% Regional
----------------------------------------------------------------------------------------------------------------
     5s AT        5s AT        5s AT        5s AT        5s AT        5s AT       5s AT       5s AT     10s AMT
----------------------------------------------------------------------------------------------------------------
                                                  CI Engine \a\
----------------------------------------------------------------------------------------------------------------
      2024 MY 7L, 22024 MY 7L, 270 hp Engine
                2024 MY 11L, 345 hp    2024 MY 15L
                      Engine                455hp
                                           Engine
----------------------------------------------------------------------------------------------------------------
                                       100% Idle Reduction = Neutral Idle