engines. Pumping losses are much lower due to lack of (or greatly
reduced) throttling. The diesel combustion cycle operates at a higher
compression ratio, with a very lean air/fuel mixture, and turbocharged
light-duty diesels typically achieve much higher torque levels at lower
engine speeds than equivalent-displacement naturally-aspirated gasoline
engines. Additionally, diesel fuel has a higher energy content per
gallon.\256\ However, diesel fuel also has a higher carbon to hydrogen
ratio, which increases the amount of CO2 emitted per gallon
of fuel used by approximately 15 percent over a gallon of gasoline.
---------------------------------------------------------------------------

    \256\ Burning one gallon of diesel fuel produces about 15
percent more carbon dioxide than gasoline due to the higher density
and carbon to hydrogen ratio.
---------------------------------------------------------------------------

    Based on confidential business information and the 2010 NAS Report,
two major areas of diesel engine design will be improved during the
2014-2018 time frame. These areas include aftertreatment improvements
and a broad range of engine improvements.
(i) Aftertreatment Improvements
    The HD diesel pickup and van segment has largely adopted the SCR
type of aftertreatment system to comply with criteria pollutant
emission standards. As the experience base for SCR expands over the
next few years, many improvements in this aftertreatment system such as
construction of the catalyst, thermal management, and reductant
optimization will result in a significant reduction in the amount of
fuel used in the process. This technology was not considered in the
light-duty rule. Based on confidential business information,

EPA and NHTSA estimate the reduction in CO2 as a result of
these improvements at 3 to 5 percent.
    The agencies have estimated the cost of this technology at $25 for
each percentage improvement in fuel consumption. This estimate is based
on the agencies' belief that this technology is, in fact, a very cost
effective approach to improving fuel consumption. As such, $25 per
percent improvement is considered a reasonable cost. This cost would
cover the engineering and test cell related costs necessary to develop
and implement the improved control strategies that would allow for the
improvements in fuel consumption. Importantly, the engineering work
involved would be expected to result in cost savings to the
aftertreatment and control hardware (lower platinum group metal
loadings, lower reductant dosing rates, etc.). Those savings are
considered to be included in the $25 per percent estimate described
here. Given the 4 percent average expected improvement in fuel
consumption results in an estimated cost of $119 (2009$) for a 2014
model year truck or van. This estimate includes a low complexity ICM of
1.24 and flat-portion of the curve learning from 2012 forward.
(ii) Engine Improvements
    Diesel engines in the HD pickup and van segment are expected to
have several improvements in their base design in the 2014-2018 time
frame. These improvements include items such as improved combustion
management, optimal turbocharger design, and improved thermal
management. This technology was not considered in the light-duty rule.
Based on confidential business information, EPA and NHTSA estimate the
reduction in CO2 as a result of these improvements at 4 to 6
percent.
    The cost for this technology includes costs associated with low
temperature exhaust gas recirculation, improved turbochargers and
improvements to other systems and components. These costs are
considered collectively in our costing analysis and termed ``diesel
engine improvements.'' The agencies have estimated the cost of diesel
engine improvements at $148 based on the cost estimates for several
individual technologies. Specifically, the direct manufacturing costs
we have estimated are: improved cylinder head, $9; turbo efficiency
improvements, $16; EGR cooler improvements, $3; higher pressure fuel
rail, $10; improved fuel injectors, $13; improved pistons, $2; and
reduced valve train friction, $95. All values are in 2009 dollars and
are applicable in the 2014 MY. Applying a low complexity ICM of 1.24
results in a cost of $184 (2009$) applicable in the 2014 MY. We
consider flat-portion of the curve learning to be appropriate for these
technologies.
(c) Transmission Technologies
    NHTSA and EPA have also reviewed the transmission technology
estimates used in the light-duty rule. In doing so, NHTSA and EPA
considered or reconsidered all available sources and updated the
estimates as appropriate. The section below describes each of the
transmission technologies considered for the final standards.
(i) Improved Automatic Transmission Control (Aggressive Shift Logic and
Early Torque Converter Lockup)
    Calibrating the transmission shift schedule to upshift earlier and
quicker, and to lock-up or partially lock-up the torque converter under
a broader range of operating conditions can reduce fuel consumption and
CO2 emissions. However, this operation can result in a
perceptible degradation in NVH. The degree to which NVH can be degraded
before it becomes noticeable to the driver is strongly influenced by
characteristics of the vehicle, and although it is somewhat subjective,
it always places a limit on how much fuel consumption can be improved
by transmission control changes. Given that the Aggressive Shift Logic
and Early Torque Converter Lockup are best optimized simultaneously due
to the fact that adding both of them primarily requires only minor
modifications to the transmission or calibration software, these two
technologies are combined in the modeling. We consider these
technologies to be present in the baseline, since 6-speed automatic
transmissions are installed in the majority of Class 2b and 3 trucks in
the 2010 model year time frame.
(ii) Automatic 6- and 8-Speed Transmissions
    Manufacturers can also choose to replace 4- 5- and 6-speed
automatic transmissions with 8-speed automatic transmissions.
Additional ratios allow for further optimization of engine operation
over a wider range of conditions, but this is subject to diminishing
returns as the number of speeds increases. As additional planetary gear
sets are added (which may be necessary in some cases to achieve the
higher number of ratios), additional weight and friction are
introduced. Also, the additional shifting of such a transmission can be
perceived as bothersome or busy to some consumers, so manufacturers
need to develop strategies for smooth shifts. Some manufacturers are
replacing 4- and 5-speed automatics with 6-speed automatics already,
and 7- and 8-speed automatics have entered production in light-duty
vehicles, albeit in lower-volume applications in luxury and performance
oriented cars.
    As discussed in the light-duty rule, confidential manufacturer data
projected that 6-speed transmissions could incrementally reduce fuel
consumption by 0 to 5 percent from a 4-speed automatic transmission,
while an 8-speed transmission could incrementally reduce fuel
consumption by up to 6 percent from a 4-speed automatic transmission.
GM has publicly claimed a fuel economy improvement of up to 4 percent
for its new 6-speed automatic transmissions.\257\
---------------------------------------------------------------------------

    \257\ General Motors, news release, ``From Hybrids to Six-
Speeds, Direct Injection And More, GM's 2008 Global Powertrain
Lineup Provides More Miles with Less Fuel'' (released Mar. 6, 2007).
Available at http:// www.gm.com/ experience/ fuel-- economy/ news/
2007/ adv-- engines/ 2008- powertrain- lineup- 082707.jsp (last
accessed Sept. 18, 2008).
---------------------------------------------------------------------------

    NHTSA and EPA reviewed and revised these effectiveness estimates
based on actual usage statistics and testing methods for these vehicles
along with confidential business information. When combined with
improved automatic transmission control, the agencies estimate the
effectiveness for a conversion from a 4- to a 6-speed transmission to
be 5.3 percent and a conversion from a 6- to 8-speed transmission to be
1.7 percent. While 8-speed transmissions were not considered in the
light-duty 2012-2016 MY vehicle rule, they are considered as a
technology of choice for this analysis in that manufacturers are
expected to upgrade the 6-speed automatic transmissions being
implemented today with 8-speed automatic transmissions in the 2014-2018
time frame. We are estimating the cost of an 8-speed automatic
transmission at $281 (2009$) relative to a 6-speed automatic
transmission in the 2014 model year. This estimate is based from the
2010 NAS Report and we have applied a low complexity ICM of 1.24 and
flat-portion of the curve learning. This technology applies to both
gasoline and diesel pickup trucks and vans.
(d) Electrification/Accessory Technologies
(i) Electrical Power Steering or Electrohydraulic Power Steering
    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 may be implemented on most vehicles with a standard
12V system. Some heavier vehicles may require a higher voltage system
which may add cost and complexity.
    The light-duty rule estimated a one to two percent effectiveness
based on the 2002 NAS report for light-duty vehicle technologies, a
Sierra Research report, and confidential manufacturer data. NHTSA and
EPA reviewed these effectiveness estimates and found them to be
accurate, thus they have been retained for purposes of this NPRM.
    NHTSA and EPA adjusted the EPS cost for the current rulemaking
based on a review of the specification of the system. Adjustments were
made to include potentially higher voltage or heavier duty system
operation for HD pickups and vans. Accordingly, higher costs were
estimated for systems with higher capability. After accounting for the
differences in system capability and applying the ICM markup of low
complexity technology of 1.24, the estimated costs are $115 for a MY
2014 truck or van (2009$). As EPS systems are in widespread usage
today, flat-portion of the curve learning is deemed applicable. EHPS
systems are considered to be of equal cost and both are considered
applicable to gasoline and diesel engines.
(ii) Improved Accessories
    The accessories on an engine, including the alternator, coolant and
oil pumps are traditionally mechanically-driven. A reduction in
CO2 emissions and fuel consumption can be realized by
driving the pumping accessories electrically, and only when needed
(``on-demand''). Alternator improvements include internal changes
resulting in lower mechanical and electrical losses combined with
control logic that charges the battery at more efficient voltage levels
and during conditions of available kinetic energy from the vehicle
which would normally be wasted energy such as braking during vehicle
decelerations.
    Electric water pumps and electric fans can provide better control
of engine cooling. For example, coolant flow from an electric water
pump can be reduced and the radiator fan can be shut off during engine
warm-up or cold ambient temperature conditions which will reduce warm-
up time, reduce warm-up fuel enrichment, and reduce parasitic losses.
    Indirect benefit may be obtained by reducing the flow from the
water pump electrically during the engine warm-up period, allowing the
engine to heat more rapidly and thereby reducing the fuel enrichment
needed during cold starting of the engine. Further benefit may be
obtained when electrification is combined with an improved, higher
efficiency engine alternator. Intelligent cooling can more easily be
applied to vehicles that do not typically carry heavy payloads, so
larger vehicles with towing capacity present a challenge, as these
vehicles have high cooling fan loads.\258\
---------------------------------------------------------------------------

    \258\ In the CAFE model, improved accessories refer solely to
improved engine cooling. However, EPA has included a high efficiency
alternator in this category, as well as improvements to the cooling
system.
---------------------------------------------------------------------------

    The agencies considered whether to include electric oil pump
technology for the rulemaking. Because it is necessary to operate the
oil pump any time the engine is running, electric oil pump technology
has insignificant effect on efficiency. Therefore, the agencies decided
to not include electric oil pump technology.
    NHTSA and EPA jointly reviewed the estimates of 1 to 2 percent
effectiveness estimates used in the light-duty rule and found them to
be accurate for Improved Electrical Accessories. Consistent with the
light-duty rule, the agencies have estimated the cost of this
technology at $93 (2009$) including a low complexity ICM of 1.24. This
cost is applicable in the 2014 model year. Improved accessory systems
are in production currently and thus flat-portion of the curve learning
is applied. This technology was considered for diesel pickup trucks and
vans only.
(e) Vehicle Technologies
(i) Mass Reduction
    Reducing a vehicle's mass, or down-weighting the vehicle, decreases
fuel consumption by reducing the energy demand needed to overcome
forces resisting motion, and rolling resistance. Manufacturers employ a
systematic approach to mass reduction, where the net mass reduction is
the addition of a direct component or system mass reduction plus the
additional mass reduction taken from indirect ancillary systems and
components, as a result of full vehicle optimization, effectively
compounding or obtaining a secondary mass reduction from a primary mass
reduction. For example, use of a smaller, lighter engine with lower
torque-output subsequently allows the use of a smaller, lighter-weight
transmission and drive line components. Likewise, the compounded weight
reductions of the body, engine and drivetrain reduce stresses on the
suspension components, steering components, wheels, tires and brakes,
allowing further reductions in the mass of these subsystems. The
reductions in unsprung masses such as brakes, control arms, wheels and
tires further reduce stresses in the suspension mounting points. This
produces a compounding effect of mass reductions.
    Estimates of the synergistic effects of mass reduction and the
compounding effect that occurs along with it can vary significantly
from one report to another. For example, in discussing its estimate, an
Auto-Steel Partnership report states that ``These secondary mass
changes can be considerable--estimated at an additional 0.7 to 1.8
times the initial mass change.'' \259\ This means for each one pound
reduction in a primary component, up to 1.8 pounds can be reduced from
other structures in the vehicle (i.e., a 180 percent factor). The
report also discusses that a primary variable in the realized secondary
weight reduction is whether or not the powertrain components can be
included in the mass reduction effort, with the lower end estimates
being applicable when powertrain elements are unavailable for mass
reduction. However, another report by the Aluminum Association, which
primarily focuses on the use of aluminum as an alternative material for
steel, estimated a factor of 64 percent for secondary mass reduction
even though some powertrain elements were considered in the
analysis.\260\ That report also notes that typical values for this
factor vary from 50 to 100 percent. Although there is a wide variation
in stated estimates, synergistic mass reductions do exist, and the
effects result in tangible mass reductions. Mass reductions in a single
vehicle component, for example a door side

impact/intrusion system, may actually result in a significantly higher
weight savings in the total vehicle, depending on how well the
manufacturer integrates the modification into the overall vehicle
design. Accordingly, care must be taken when reviewing reports on
weight reduction methods and practices to ascertain if compounding
effects have been considered or not.
---------------------------------------------------------------------------

    \259\ ``Preliminary Vehicle Mass Estimation Using Empirical
Subsystem Influence Coefficients,'' Malen, D.E., Reddy, K. Auto-
Steel Partnership Report, May 2007, Docket EPA-HQ-OAR-2009-0472-
0169. Accessed on the Internet on May 30, 2009 at: http://www.a-sp.org/database/custom/Mass%20Compounding%20-%20Final%20Report.pdf.
    \260\ ``Benefit Analysis: Use of Aluminum Structures in
Conjunction with Alternative Powertrain Technologies in
Automobiles,'' Bull, M. Chavali, R., Mascarin, A., Aluminum
Association Research Report, May 2008, Docket EPA-HQ-OAR-2009-0472-
0168. Accessed on the Internet on April 30, 2009 at: http://www.autoaluminum.org/downloads/IBIS-Powertrain-Study.pdf.
---------------------------------------------------------------------------

    Mass reduction is broadly applicable across all vehicle subsystems
including the engine, exhaust system, transmission, chassis,
suspension, brakes, body, closure panels, glazing, seats and other
interior components, engine cooling systems and HVAC systems. It is
estimated that up to 1.25 kilograms of secondary weight savings can be
achieved for every kilogram of weight saved on a light-duty vehicle
when all subsystems are redesigned to take into account the initial
primary weight savings.261 262
---------------------------------------------------------------------------

    \261\ ``Future Generation Passenger Compartment-Validation (ASP
241)'' Villano, P.J., Shaw, J.R., Polewarczyk, J., Morgans, S.,
Carpenter, J.A., Yocum, A.D., in ``Lightweighting Materials--FY 2008
Progress Report,'' U.S. Department of Energy, Office of Energy
Efficiency and Renewable Energy, Vehicle Technologies Program, May
2009, Docket EPA-HQ-OAR-2009-0472-0190.
    \262\ ``Preliminary Vehicle Mass Estimation Using Empirical
Subsystem Influence Coefficients,'' Malen, D.E., Reddy, K. Auto-
Steel Partnership Report, May 2007, Docket EPA-HQ-OAR-2009-0472-
0169. Accessed on the Internet on May 30, 2009 at: http://www.a-sp.org/database/custom/Mass%20Compounding%20-%20Final%20Report.pdf.
---------------------------------------------------------------------------

    Mass reduction can be accomplished by proven methods such as:
     Smart Design: Computer aided engineering (CAE) tools can
be used to better optimize load paths within structures by reducing
stresses and bending moments applied to structures. This allows better
optimization of the sectional thicknesses of structural components to
reduce mass while maintaining or improving the function of the
component. Smart designs also integrate separate parts in a manner that
reduces mass by combining functions or the reduced use of separate
fasteners. In addition, some ``body on frame'' vehicles are redesigned
with a lighter ``unibody'' construction.
     Material Substitution: Substitution of lower density and/
or higher strength materials into a design in a manner that preserves
or improves the function of the component. This includes substitution
of high-strength steels, aluminum, magnesium or composite materials for
components currently fabricated from mild steel.
     Reduced Powertrain Requirements: Reducing vehicle weight
sufficiently allows for the use of a smaller, lighter and more
efficient engine while maintaining or increasing performance.
Approximately half of the reduction is due to these reduced powertrain
output requirements from reduced engine power output and/or
displacement, changes to transmission and final drive gear ratios. The
subsequent reduced rotating mass (e.g., transmission, driveshafts/
halfshafts, wheels and tires) via weight and/or size reduction of
components are made possible by reduced torque output requirements.
     Automotive companies have largely used weight savings in
some vehicle subsystems to offset or mitigate weight gains in other
subsystems from increased feature content (sound insulation,
entertainment systems, improved climate control, panoramic roof, etc.).
     Lightweight designs have also been used to improve vehicle
performance parameters by increased acceleration performance or
superior vehicle handling and braking.
    Many manufacturers have already announced final future products
plans reducing the weight of a vehicle body through the use of high
strength steel body-in-white, composite body panels, magnesium alloy
front and rear energy absorbing structures reducing vehicle weight
sufficiently to allow a smaller, lighter and more efficient engine.
Nissan will be reducing average vehicle curb weight by 15 percent by
2015.\263\ Ford has identified weight reductions of 250 to 750 lb per
vehicle as part of its implementation of known technology within its
sustainability strategy between 2011 and 2020.\264\ Mazda plans to
reduce vehicle weight by 220 pounds per vehicle or more as models are
redesigned.265 266 Ducker International estimates that the
average curb weight of light-duty vehicle fleet will decrease
approximately 2.8 percent from 2009 to 2015 and approximately 6.5
percent from 2009 to 2020 via changes in automotive materials and
increased change-over from previously used body-on-frame automobile and
light-truck designs to newer unibody designs.\263\ While the
opportunity for mass reductions available to the light-duty fleet may
not in all cases be applied directly to the heavy-duty fleet due to the
different designs for the expected duty cycles of a ``work'' vehicle,
mass reductions are still available particularly to areas unrelated to
the components and systems necessary for the work vehicle aspects.
---------------------------------------------------------------------------

    \263\ ``Lighten Up!,'' Brooke, L., Evans, H. Automotive
Engineering International, Vol. 117, No. 3, March 2009.
    \264\ ``2008/9 Blueprint for Sustainability,'' Ford Motor
Company. Available at: http://www.ford.com/go/sustainability (last
accessed February 8, 2010).
    \265\ ``Mazda to cut vehicle fuel consumption 30 percent by
2015,'' Mazda press release, June 23, 2009. Available at: http://www.mazda.com/publicity/release/2008/200806/080623.html (last
accessed February 8, 2010).
    \266\ ``Mazda: Don't believe hot air being emitted by hybrid
hype,'' Greimel, H. Automotive News, March 30, 2009.
---------------------------------------------------------------------------

    Due to the payload and towing requirements of these heavy-duty
vehicles, engine downsizing was not considered in the estimates for
CO2 reduction in the area of mass reduction and material
substitution. NHTSA and EPA estimate that a 3 percent mass reduction
with no engine downsizing results in a 1 percent reduction in fuel
consumption. In addition, a 5 and 10 percent mass reduction with no
engine downsizing result in an estimated CO2 reduction of
1.6 and 3.2 percent respectively. These effectiveness values are 50
percent of the light-duty rule values due to the elimination of engine
downsizing for this class of vehicle.
    In the NPRM, EPA and NHTSA relied on three studies to estimate the
cost of vehicle mass reduction. The agencies used a value of $1.32 per
pound of mass reduction that was derived from a 2002 National Academy
of Sciences study, a 2008 Sierra Research report, and a 2008 MIT study.
The cost was estimated to be constant, independent of the level of mass
reduction.
    The agencies along with the California Air Resources Board (CARB)
have recently completed work on an Interim Joint Technical Assessment
Report (TAR) that considers light-duty GHG and fuel economy standards
for model years 2017 through 2025 and have continued this work to
support the light-duty vehicle NPRM, which is expected to be issued
this fall. Based on new information from various industry and
literature sources, the TAR modified the mass reduction/cost
relationship used in the light-duty 2012-2016 MY vehicle rule to begin
at the origin (zero cost at zero percent mass reduction) and to have
increasing cost with increasing mass reduction.\267\ The resulting
analysis showed costs for 5 percent mass reduction on light-duty
vehicles to be near zero or cost parity.
---------------------------------------------------------------------------

    \267\ ``Interim Joint Technical Assessment Report: Light-Duty
Vehicle Greenhouse Gas Emission Standards and Corporate Average Fuel
Economy Standards for Model Years 2017-2025;'' September 2010;
available at http://epa.gov/otaq/climate/regulations/ldv-ghg-tar.pdf
and in the docket for this rule.
---------------------------------------------------------------------------

    In the proposal for heavy-duty vehicles, we estimated mass
reduction costs based on the 2012-2016 light-duty analysis without
accounting for the new work completed in the Interim Joint Technical
Assessment and additional

work the agencies have considered for the upcoming light-duty vehicle
NPRM. Since the heavy-duty vehicle proposal, the agencies have been
able to consider updated cost estimates in the context of both light-
duty and heavy-duty vehicle bodies of work. While the agencies intend
to discuss the additional work for the light-duty NPRM in much more
detail in the documents for that rulemaking, we think it appropriate to
explain here that after having considered a number of additional and
highly-varying sources, the agencies believe that the cost estimates
used in the TAR may have been lower than would be reasonable for HD
pickups and vans, given their different and work-related uses and thus
different construction as compared to the light-duty vehicles evaluated
in the TAR. We do not believe that all of the weight reduction
opportunities for light-duty vehicles can be applied to heavy-duty
trucks. However, we do believe reductions in the following components
and systems can be found that do not affect the payload and towing
requirements of these heavy-duty vehicles: Body, closure panels,
glazing, seats and other interior components, engine cooling systems
and HVAC systems.
    The agencies have reviewed and considered many different mass
reduction studies during the technical assessment for the heavy-duty
vehicle GHG and fuel efficiency rulemaking. The agencies found that
many of the studies on this topic vary considerably in their rigor,
transparency, and applicability to the regulatory assessment. Having
considered a variety of options, the agencies for this heavy-duty
analysis have been unable to come up with a way to quantitatively
evaluate the available studies. Therefore, the agencies have chosen a
value within the range of the available studies that the agencies
believe is reasonable. The studies and manufacturers' confidential
business information relied upon in determining the final mass
reduction costs are summarized in Figure 2.1, Section 2.3.6 of the RIA.
Each study relied upon by the agencies in this determination has also
been placed in the agencies' respective dockets. See NHTSA-2010-0079;
EPA-HQ-0AR-2010-0162.
    The agencies note that the NAS 2010 study provided estimates of
mass reduction costs, but the agencies did not consider using the NAS
2010 study as the single source of mass reduction cost estimates
because the NAS 2010 estimates were not based on literature reports
that focused on trucks or were necessarily appropriate for MD/HD
vehicles, and also because a variety of newer and more rigorous studies
were available to the agencies than those relied upon by the NAS in
developing its estimates. We note, however, that for a 5 percent
reduction in mass, the NAS 2010 report estimates a per pound cost of
mass reduction of $1.65.
    Thus, we are estimating the direct manufacturing costs for a 5
percent mass reduction of a 6,000 lb vehicle at a range of $75-$90 per
vehicle. With additional margin for uncertainty, we arrive at a direct
manufacturing cost of $85-$100, which is roughly in the upper middle of
the range of values that resulted from the additional and highly-
varying studies mentioned above that were considered in the agencies'
review. We have broken this down for application to HD pickup trucks
and vans as follows: Class 2b gasoline $85, Class 2b diesel $95, Class
3 gasoline $90, and Class 3 diesel trucks $100. Applying the low
complexity ICM of 1.24 results in estimated total costs for a 5 percent
mass reduction applicable in the 2016 model year as follows: Class 2b
gasoline $108, Class 2b diesel $121, Class 3 gasoline $115, and Class 3
diesel trucks $127. All mass reduction costs stated here are in 2009
dollars.
(ii) Low Rolling Resistance Tires
    Tire rolling resistance is the frictional loss associated mainly
with the energy dissipated in the deformation of the tires under load
and thus influences fuel efficiency and CO2 emissions. Other
tire design characteristics (e.g., materials, construction, and tread
design) influence durability, traction (both wet and dry grip), vehicle
handling, and ride comfort in addition to rolling resistance. A typical
LRR tire's attributes would include: increased tire inflation pressure,
material changes, and tire construction with less hysteresis, geometry
changes (e.g., reduced aspect ratios), and reduction in sidewall and
tread deflection. These changes would generally be accompanied with
additional changes to suspension tuning and/or suspension design.
    EPA and NHTSA estimated a 1 to 2 percent increase in effectiveness
with a 10 percent reduction in rolling resistance, which was based on
the 2010 NAS Report findings and consistent with the light-duty rule.
    Based on the light-duty rule and the 2010 NAS Report, the agencies
have estimated the cost for LRR tires to be $7 per Class 2b truck or
van, and $10 per Class 3 truck or van (both values in 2009$ and
inclusive of a 1.24 low complexity markup).\268\ The higher cost for
the Class 3 trucks and vans is due to the predominant use of dual rear
tires and, thus, 6 tires per truck. Due to the commodity-based nature
of this technology, cost reductions due to learning are not applied.
This technology is considered applicable to both gasoline and diesel.
---------------------------------------------------------------------------

    \268\ ``Tires and Passenger Vehicle Fuel Economy,''
Transportation Research Board Special Report 286, National Research
Council of the National Academies, 2006, Docket EPA-HQ-OAR-2009-
0472-0146.
---------------------------------------------------------------------------

(iii) Aerodynamic Drag Reduction
    Many factors affect a vehicle's aerodynamic drag and the resulting
power required to move it through the air. While these factors change
with air density and the square and cube of vehicle speed,
respectively, the overall drag effect is determined by the product of
its frontal area and drag coefficient, Cd. Reductions in these
quantities can therefore reduce fuel consumption and CO2
emissions. Although frontal areas tend to be relatively similar within
a vehicle class (mostly due to market-competitive size requirements),
significant variations in drag coefficient can be observed. Significant
changes to a vehicle's aerodynamic performance may need to be
implemented during a redesign (e.g., changes in vehicle shape).
However, shorter-term aerodynamic reductions, with a somewhat lower
effectiveness, may be achieved through the use of revised exterior
components (typically at a model refresh in mid-cycle) and add-on
devices that currently are being applied. The latter list would include
revised front and rear fascias, modified front air dams and rear
valances, addition of rear deck lips and underbody panels, and lower
aerodynamic drag exterior mirrors.
    The light-duty 2012-2016 MY vehicle rule estimated that a fleet
average of 10 to 20 percent total aerodynamic drag reduction is
attainable which equates to incremental reductions in fuel consumption
and CO2 emissions of 2 to 3 percent for both cars and
trucks. These numbers are generally supported by confidential
manufacturer data and public technical literature. For the heavy-duty
truck category, a 5 to 10 percent total aerodynamic drag reduction was
considered due to the different structure and use of these vehicles
equating to incremental reductions in fuel consumption and
CO2 emissions of 1 to 2 percent.
    Consistent with the light-duty rule, the agencies have estimated
the cost for this technology at $58 (2009$) including a low complexity
ICM of 1.24. This cost is applicable in the 2014 model year to

both gasoline and diesel pickup trucks and vans.
(3) What are the projected technology packages' effectiveness and cost?
    The assessment of the final technology effectiveness was developed
through the use of the EPA Lumped Parameter model developed for the
light-duty rule. Many of the technologies were common with the light-
duty assessment but the effectiveness of individual technologies was
appropriately adjusted to match the expected effectiveness when
implemented in a heavy-duty application. The model then uses the
individual technology effectiveness levels but then takes into account
technology synergies. The model is also designed to prevent double
counting from technologies that may directly or indirectly impact the
same physical attribute (e.g., pumping loss reductions).
    To achieve the levels of the final standards for gasoline and
diesel powered heavy-duty vehicles, the technology packages were
determined to generally require the technologies previously discussed
respective to unique gasoline and diesel technologies. Although some of
the technologies may already be implemented in a portion of heavy-duty
vehicles, none of the technologies discussed are considered ubiquitous
in the heavy-duty fleet. Also, as would be expected, the available test
data shows that some vehicle models will not need the full complement
of available technologies to achieve the final standards. Furthermore,
many technologies can be further improved (e.g., aerodynamic
improvements) from today's best levels, and so allow for compliance
without needing to apply a technology that a manufacturer might deem
less desirable.
    Technology costs for HD pickup trucks and vans are shown in Table
III-11.

  Table III-11--Technology Costs for HD Pickup Trucks & Vans Inclusive of Indirect Cost Markups for the 2014MY
                                                     [2009$]
----------------------------------------------------------------------------------------------------------------
                                                                Class 2b     Class 2b     Class 3      Class 3
                         Technology                             gasoline      diesel      gasoline      diesel
----------------------------------------------------------------------------------------------------------------
Low friction lubes..........................................           $4           $4           $4           $4
Engine friction reduction...................................          116          N/A          116          N/A
Stoichiometric gasoline direct injection....................          481          N/A          481          N/A
Engine improvements.........................................          N/A          184          N/A          184
8s automatic transmission (increment to 6s automatic                  281          281          281          281
 transmission)..............................................
Improved accessories........................................          N/A           93          N/A           93
Low rolling resistance tires................................            7            7           10           10
Aerodynamic improvements....................................           58           58           58           58
Electric (or electro/hydraulic) power steering..............          115          115          115          115
Aftertreatment improvements.................................          N/A          119          N/A          119
Mass reduction (5%).........................................          108          121          115          127
Air conditioning............................................           21           21           21           21
    Total...................................................        1,190        1,003        1,209        1,013
                                                             ---------------------------------------------------
At 15% phase-in in 2014.....................................          179          150          180          152
----------------------------------------------------------------------------------------------------------------

(4) Reasonableness of the Final Standards
    The final standards are based on the application of the control
technologies described in this section. These technologies are
available within the lead time provided, as discussed in RIA Chapter
2.3. These controls are estimated to add costs of approximately $1,048
for MY 2018 heavy-duty pickups and vans. Reductions associated with
these costs and technologies are considerable, estimated at a 12
percent reduction of CO2eq emissions from the MY 2010
baseline for gasoline engine-equipped vehicles and 17 percent for
diesel engine equipped vehicles, estimated to result in reductions of
18 MMT of CO2eq emissions over the lifetimes of 2014 through
2018 MY vehicles.\269\ The reductions are cost effective, estimated at
$90 per ton of CO2eq removed in 2030.\270\ This cost is
consistent with the light-duty rule which was estimated at $100 per ton
of CO2eq removed in 2020 excluding fuel savings. Moreover,
taking into account the fuel savings associated with the program, the
cost becomes -$230 per ton of CO2eq (i.e. a savings of $230
per ton) in 2030. The cost of controls is fully recovered due to the
associated fuel savings, with a payback period in the second year of
ownership, as shown in Table VIII-9 below in Section VIII. Given the
large, cost effective emission reductions based on use of feasible
technologies which are available in the lead time provided, plus the
lack of adverse impacts on vehicle safety or utility, EPA and NHTSA
regard these final standards as appropriate and consistent with our
respective statutory authorities under CAA section 202(a) and NHTSA's
EISA authority under 49 U.S.C. 32902(k)(2). Based on the discussion
above, NHTSA believes these standards are the maximum feasible under
EISA.
---------------------------------------------------------------------------

    \269\ See Table VI-4 of this preamble.
    \270\ See Table 0-3 of this preamble.
---------------------------------------------------------------------------

(5) Alternative HD Pickup Truck and Van Standards Considered
    The agencies rejected consideration of any less stringent standards
given that the standards adopted are feasible at reasonable cost and
cost-effectiveness within the lead time of the program. Furthermore, as
explained above, because the standards are premised on 100 percent
application of available technologies during this period, the agencies
rejected adoption of more stringent standards. The agencies have also
explained above why the phase-in period for the standards is reasonable
and that attempting more aggressive phase-ins would start to force
changes outside normal redesign cycles at likely exorbitant cost.

C. Class 2b-8 Vocational Vehicles

    Vocational vehicles cover a wide variety of applications which
influence both the body style and usage patterns. They also are built
using a complex process, which includes additional entities such as
body builders. These factors create special sensitivity to

concerns of needed lead time, as well as developing standards that do
not interfere with vocational vehicles' utility. The agencies are
adopting a standard for vocational vehicles for the first phase of the
program that relies on less extensive addition of technology than do
the other regulatory categories as well as making the chassis
manufacturer the manufacturer subject to the standard. We intend that
future rulemakings will consider increased stringency and possibly more
application-specific standards. The agencies are also finalizing
standards for the diesel and gasoline engines installed in vocational
vehicles, similar to those discussed above for HD engines installed in
Class 7 and 8 tractors.
(1) What technologies did the agencies consider to reduce the
CO2 emissions and fuel consumption of vocational vehicles?
    Similar to the approach taken with tractors, the agencies evaluated
aerodynamic, tire, idle reduction, weight reduction, hybrid powertrain,
and engine technologies and their impact on reducing fuel consumption
and GHG emissions. The engines used in vocational vehicles include both
gasoline and diesel engines, thus, each type is discussed separately
below. As explained in Section II.D.1.b, the final regulatory structure
for heavy-duty engines separates the compression ignition (or
``diesel'') engines into three regulatory subcategories--light heavy,
medium heavy, and heavy heavy diesel engines--while spark ignition (or
``gasoline'') engines are a single regulatory subcategory (an approach
for which there was consensus in the public comments). Therefore, the
subsequent discussion will assess each type of engine separately.
(a) Vehicle Technologies
    Vocational vehicles typically travel fewer miles than combination
tractors. They also tend to be used in more urban locations (with
consequent stop and start drive cycles). Therefore the average speed of
vocational vehicles is significantly lower than combination tractors.
This has a significant effect on the types of technologies that are
appropriate to consider for reducing CO2 emissions and fuel
consumption.
    The agencies considered the type of technologies for vocational
vehicles based on the energy losses of a typical vocational vehicle.
The technologies are similar to the ones considered for combination
tractors. Argonne National Lab conducted an energy audit using
simulation tools to evaluate the energy losses of vocational vehicles,
such as a Class 6 pickup and delivery truck. Argonne found that 74
percent of the energy losses are attributed to the engine, 13 percent
to tires, 9 percent to aerodynamics, two percent to transmission
losses, and the remaining four percent of losses to axles and
accessories for a medium-duty truck traveling at 30 mph.\271\
---------------------------------------------------------------------------

    \271\ Argonne National Lab. Evaluation of Fuel Consumption
Potential of Medium and Heavy-duty Vehicles through Modeling and
Simulation. October 2009. Page 89.
---------------------------------------------------------------------------

    Low 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 (as just mentioned). The
range of rolling resistance of tires used on vocational vehicles today
is large. 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 truck buyers to value
tire traction and durability more heavily than rolling resistance.
Therefore, the agencies concluded that a regulatory program that seeks
to optimize tire rolling resistance in addition to traction and
durability can bring about fuel consumption and CO2 emission
reductions from this segment. The 2010 NAS report states that rolling
resistance impact on fuel consumption reduces with mass of the vehicle
and with drive cycles with more frequent starts and stops. The report
found that the fuel consumption reduction opportunity for reduced
rolling resistance ranged between one and three percent in the 2010
through 2020 time frame.\272\ The agencies estimate that average
rolling resistance from tires in 2010 model year can be reduced by 10
percent for 50 percent of the vehicles by 2014 model year based on the
tire development achievements over the last several years in the line
haul truck market.
---------------------------------------------------------------------------

    \272\ See 2010 NAS Report, Note 197, page 146.
---------------------------------------------------------------------------

    Aerodynamics: The Argonne National lab work shows that aerodynamics
has less of an impact on vocational vehicle energy losses than do
engines or tires. In addition, the aerodynamic performance of a
complete vehicle is significantly influenced by the body of the
vehicle. The agencies are not regulating body builders in this phase of
regulations for the reasons discussed in Section II. Therefore, we are
not basing any of the final standards for vocational vehicles on
aerodynamic improvements. Nor would aerodynamic performance be input
into GEM to demonstrate compliance.
    Weight Reduction: NHTSA and EPA are also not basing any of the
final vocational vehicle standards on use of vehicle weight reduction.
Thus, vehicle mass reductions are not an input into GEM. The agencies
are taking this approach despite comments suggesting that the agencies
make use of weight reductions for this segment, because we are unable
to quantify the potential impact of weight reduction on vehicle utility
in this broad segment. Vocational vehicles serve an incredibly diverse
range of functions. Each of these unique vehicle functions is likely to
have its own unique tradeoff between vehicle utility and the potential
for vehicle mass reduction. The agencies have not been able at this
time to determine the degree to which such tradeoffs exist nor the
specific level of the tradeoff for each unique vehicle vocation. No
commenter provided data to inform this question. Absent this
information, the agencies cannot at this time project the potential for
worthwhile weight reductions from vocational vehicles.
    Drivetrain: Optimization of vehicle gearing to engine performance
through selection of transmission gear ratios, final drive gear ratios
and tire size can play a significant role in reducing fuel consumption
and GHGs. Optimization of gear selection versus vehicle and engine
speed accomplished through driver training or automated transmission
gear selection can provide additional reductions. The 2010 NAS report
found that the opportunities to reduce fuel consumption in heavy-duty
vehicles due to transmission and driveline technologies in the 2015
time frame ranged between 2 and 8 percent.\273\ Initially, the agencies
considered reflecting transmission choices and technology in our
standard setting process for both tractors and vocational vehicles (see
previous discussion above on automated manual and automatic
transmissions for tractors). We have however decided not to do so for
the following reasons.
---------------------------------------------------------------------------

    \273\ See 2010 NAS Report, Note 197, pp 134 and 137.
---------------------------------------------------------------------------

    The primary factors that determine optimum gear selection are
vehicle weight, vehicle aerodynamics, vehicle speed, and engine
performance typically considered on a two dimensional map of engine
speed and torque. For a given power demand (determined by speed,
aerodynamics and vehicle mass) an optimum transmission and gearing
setup will keep the engine power delivery operating at the best speed
and torque points for highest engine

efficiency. Since power delivery from the engine is the product of
speed and torque a wide range of torque and speed points can be found
that deliver adequate power, but only a smaller subset will provide
power with peak efficiency. Said more generally, the design goal is for
the transmission to deliver the needed power to the vehicle while
maintaining engine operation within the engine's ``sweet spot'' for
most efficient operation. Absent information about vehicle mass and
aerodynamics (which determines road load at highway speeds) it is not
possible to optimize the selection of gear ratios for lowest fuel
consumption. Truck and chassis manufacturers today offer a wide range
of tire sizes, final gear ratios and transmission choices so that final
bodybuilders can select an optimal combination given the finished
vehicle weight, general aerodynamic characteristics and expected
average speed. In order to set fuel efficiency and GHG standards that
would reflect these optimizations, the agencies would need to regulate
a wide range of small entities that are final bodybuilders, would need
to set a large number of uniquely different standards to reflect the
specific weight and aerodynamic differences and finally would need test
procedures to evaluate these differences that would not themselves be
excessively burdensome. Finally, the agencies would need the underlying
data regarding effectively all of the vocational trucks produced today
in order to determine the appropriate standards. Because the market is
already motivated to reach these optimizations themselves today,
because we have insufficient data to determine appropriate standards,
and finally, because we believe the testing burden would be
unjustifiably high, we are not finalizing to reflect transmission and
gear ratio optimization in our GEM or in our standard setting.
    Some commenters suggested that the agencies predicate the
vocational vehicle standard on the use of specific transmission
technologies for example automated manual transmissions believing that
these mechanically more efficient designs would inherently provide
better fuel efficiency and lower greenhouse gas emissions than
conventional torque convertor automatic transmission designs. However
as discussed above the agencies believe that the small mechanical
efficiency differences between these transmission designs are
relatively insignificant in the context of the dominant impact of
proper gear ratio selection in determining a vehicle's overall
performance. In many cases, the mechanically more efficient design may
prove less effective in use if other aspects of vehicle performance
(such a vehicle launch under load) compromise the selection of gear
ratios. This somewhat surprising outcome can be seen most readily by
looking at modern passenger cars where mechanically less efficient
torque converter automatic models often produce equal or better fuel
economy when compared to the more mechanically efficient manual
transmission versions of the same vehicles. Given this reality, we do
not believe it would be appropriate to base the vocational truck
standard on the use of a particular transmission technology. In the
future, if we develop a complete vehicle chassis test approach to
regulating this segment, we would then be able to incorporate
transmission performance as we already do for the heavy-duty pickup
truck and van segment.
    Idle Reduction: Episodic idling by vocational vehicles occurs
during the workday, unlike the overnight idling of combination tractors
(see discussion in Section III.A.2.a). Vocational vehicle idling can be
divided into two typical types. The first type is idling while
waiting--such as during a pickup or delivery. This type of idling can
be reduced through automatic engine shut-offs. The second type of
idling is to accomplish PTO operation, such as compacting garbage or
operating a bucket. The agencies have found only one study that
quantifies the emissions due to idling conducted by Argonne National
Lab based on 2002 VIUS data.\274\ EPA conducted a work assignment to
assist in characterizing PTO operations. The study of a utility truck
used in two different environments (rural and urban) and a refuse
hauler found that the PTO operated on average 28 percent of time
relative to the total time spent driving and idling.\275\ The use of
hybrid powertrains to reduce idling is discussed below.
---------------------------------------------------------------------------

    \274\ Gaines, Linda, A. Vyas, J. Anderson (Argonne National
Laboratory). Estimation of Fuel Use by Idling Commercial Trucks.
January 2006.
    \275\ Southwest Research Institute. Power Take Off Cycle
Development and Testing. 2010. Docket EPA-HQ-OAR-2010-0162-3335.
---------------------------------------------------------------------------

    Hybrid Powertrains: Several types of vocational vehicles are well
suited for hybrid powertrains. 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. The hybrids developed to date
have seen fuel consumption and CO2 emissions reductions
between 20 and 50 percent in the field. However, there are still some
key issues that are restricting the penetration of hybrids, including
overall system cost, battery technology, and lack of cost-effective
electrified accessories. We have not predicated the standards based on
the use of hybrids reflecting the still nascent level of technology
development and the very small fraction of vehicle sales they would be
expected to account for in this time frame--on the order of only a
percent or two. Were we to overestimate the number of hybrids that
could be produced, we would set a standard that is not feasible. We
believe that it is more appropriate given the status of technology
development and our hopes for future advancements in hybrid
technologies to encourage their production through incentives. Thus, to
create an incentive for early introduction of hybrid powertrains into
the vocational vehicle fleet, the agencies are adopting the proposed
advanced technology credits if hybrid powertrains are used as a
technology to meet the vocational vehicle standard (or any other
vehicle standard), as described in Section IV.
(b) Gasoline Engine Technologies
    The gasoline (or spark ignited) engines certified and sold as loose
engines into the heavy-duty truck market are typically large V8 and V10
engines produced by General Motors and Ford. The basic architecture of
these engines is the same as the versions used in the heavy-duty pickup
trucks and vans. Therefore, the technologies analyzed by the agencies
mirror the gasoline engine technologies used in the heavy-duty pickup
truck analysis in Section III.B above.
    Building on the technical analysis underlying the light-duty 2012-
2016 MY vehicle rule, the agencies took a fresh look at technology
effectiveness values for purposes of this analysis using as a starting
point the estimates from that rule. The agencies then considered the
impact of test procedures (such as higher test weight of HD pickup
trucks and vans) on the effectiveness estimates. The agencies also
considered other sources such as the 2010 NAS Report, recent CAFE
compliance data, and confidential manufacturer estimates of technology
effectiveness. NHTSA and EPA engineers reviewed effectiveness
information from the multiple sources for each technology and ensured
that such effectiveness estimates were based

on technology hardware consistent with the BOM components used to
estimate costs.
    The agencies note that the effectiveness values estimated for the
technologies may represent average values, and do not reflect the
potentially-limitless spectrum 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 lubricants, each vehicle could have a unique effectiveness
estimate depending on the baseline vehicle's oil viscosity rating. For
purposes of this final 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 engines) might obtain
from adding a fuel-saving technology.
    Baseline Engine: Similar to the gasoline engine used as the
baseline in the light-duty rule, the agencies assumed the baseline
engine in this segment to be a naturally aspirated, overhead valve V8
engine.\276\ The agencies did not receive any comments regarding the
baseline engine assumptions in the proposal. The following discussion
of effectiveness is generally in comparison to 2010 baseline engine
performance.
---------------------------------------------------------------------------

    \276\ The agencies note that baseline did not include coupled
cam phasing for loose HD gasoline engines. The HD loose engines are
slightly different than the ones used in the HD pickup trucks. They
tend to be the older versions of the same engine.
---------------------------------------------------------------------------

    For the final rulemaking, the agencies considered the same set of
technologies for loose gasoline engines at proposal. The agencies
received comments which suggested that the agencies consider
electrification of accessories to reduce the fuel consumption and
CO2 emissions from heavy-duty gasoline engines.
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. However, technologies
such as these improvements to accessories are not demonstrated using
the engine dynamometer test procedures being adopted in this final rule
because those systems are not installed on the engine during the
testing. Thus, the technologies the agencies considered include the
following:
    Engine Friction Reduction: In addition to low friction lubricants,
manufacturers can also reduce friction and improve fuel consumption by
improving the design of engine components and subsystems. Examples
include improvements in low-tension piston rings, piston skirt design,
roller cam followers, improved crankshaft design and bearings, material
coatings, material substitution, more optimal thermal management, and
piston and cylinder surface treatments. The 2010 NAS, NESCCAF \277\ and
EEA \278\ reports as well as confidential manufacturer data used in the
light-duty vehicle rulemaking suggested a range of effectiveness for
engine friction reduction to be between 1 to 3 percent. NHTSA and EPA
continue to believe that this range is accurate.
---------------------------------------------------------------------------

    \277\ Northeast States Center for a Clean Air Future. ``Reducing
Greenhouse Gas Emissions from Light-Duty Motor Vehicles.'' September
2004.
    \278\ Energy and Environmental Analysis, Inc. ``Technology to
Improve the Fuel Economy of Light Duty Trucks to 2015.'' May 2006.
---------------------------------------------------------------------------

    Coupled Cam Phasing: Valvetrains with coupled (or coordinated) cam
phasing can modify the timing of both the inlet valves and the exhaust
valves an equal amount by phasing the camshaft of a single overhead cam
engine or an overhead valve engine. Based on the light-duty 2012-2016
MY vehicle rule, previously-received confidential manufacturer data,
and the NESCCAF report, NHTSA and EPA estimated the effectiveness of
couple cam phasing CCP to be between 1 and 4 percent. NHTSA and EPA
reviewed this estimate for purposes of the NPRM, and continue to find
it accurate.
    Cylinder Deactivation: In conventional spark-ignited engines
throttling the airflow controls engine torque output. At partial loads,
efficiency can be improved by using cylinder deactivation instead of
throttling. Cylinder deactivation can improve engine efficiency by
disabling or deactivating (usually) half of the cylinders when the load
is less than half of the engine's total torque capability--the valves
are kept closed, and no fuel is injected--as a result, the trapped air
within the deactivated cylinders is simply compressed and expanded as
an air spring, with reduced friction and heat losses. The active
cylinders combust at almost double the load required if all of the
cylinders were operating. Pumping losses are significantly reduced as
long as the engine is operated in this ``part cylinder'' mode.
Effectiveness improvements scale roughly with engine displacement-to-
vehicle weight ratio: The higher displacement-to-weight vehicles,
operating at lower relative loads for normal driving, have the
potential to operate in part-cylinder mode more frequently. Cylinder
deactivation is less effective on heavily-loaded vehicles because they
require more power and spend less time in areas of operation where only
partial power is required. The technology also requires proper
integration into the vehicles which is difficult in the vocational
vehicle segment where often the engine is sold to a chassis
manufacturer or body builder without knowing the type of transmission
or axle used in the vehicle or the precise duty cycle of the vehicle.
The cylinder deactivation requires fine tuning of the calibration as
the engine moves into and out of deactivation mode to achieve
acceptable NVH. Additionally, cylinder deactivation would be difficult
to apply to vehicles with a manual transmission because it requires
careful gear change control. NHTSA and EPA adjusted the 2012-16 MY
light-duty rule estimates using updated power to weight ratings of
heavy-duty trucks and confidential business information and downwardly
adjusted the effectiveness to 0 to 3 percent for these vehicles to
reflect the differences in drive cycle and operational opportunities
compared to light-duty vehicles. Because of the complexities associated
with integrating cylinder deactivation in a non-integrated vehicle
assembly process and the low effectiveness of the technology, the
agencies did not include cylinder deactivation in the final gasoline
engine technology package.
    Stoichiometric gasoline direct injection: SGDI (also known as
spark-ignition direct injection engines) inject fuel at high pressure
directly into the combustion chamber (rather than the intake port in
port fuel injection). Direct injection of the fuel into the cylinder
improves cooling of the air/fuel charge within the cylinder, which
allows for higher compression ratios and increased thermodynamic
efficiency without the onset of combustion knock. Recent injector
design advances, improved electronic engine management systems and the
introduction of multiple injection events per cylinder firing cycle
promote better mixing of the air and fuel, enhance combustion rates,
increase residual exhaust gas tolerance and improve cold start
emissions. SGDI engines achieve higher power density and match well
with other technologies, such as boosting and variable valvetrain
designs. The light-duty 2012-2016 MY vehicle rule estimated the
effectiveness

of SGDI to be between 2 and 3 percent. NHTSA and EPA revised these
estimated accounting for the use and testing methods for these vehicles
along with confidential business information estimates received from
manufacturers while developing the program. Based on these revisions,
NHTSA and EPA estimate the range of 1 to 2 percent for SGDI.
(c) Diesel Engine Technologies
    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.
    Baseline Engine: There are three baseline diesel engines, a Light,
Medium, and a Heavy Heavy-duty Diesel engine. The agencies developed
the baseline diesel engine as a 2010 model year engine with an
aftertreatment system which meets EPA's 0.2 grams of NOX/
bhp-hr standard with an SCR system along with EGR and meets the PM
emissions standard with a diesel particulate filter with active
regeneration. The engine is turbocharged with a variable geometry
turbocharger. As noted above in Section III.A.1.b, the agencies
received comments from Navistar stating that the agencies used an
artificially low baseline CO2 emissions level which was
tilted toward the use of SCR aftertreatment system. As discussed in
Section III.A.1.b, the agencies disagree with the statement that SCR is
infeasible. Additional responses from the agencies are available in the
Response to Comments document, Section 6.2.\279\ The following
discussion of technologies describes improvements over the 2010 model
year baseline engine performance, unless otherwise noted. Further
discussion of the baseline engine and its performance can be found in
Section III.C.2.(c)(i) below. The following discussion of effectiveness
is generally in comparison to 2010 baseline engine performance, and is
in reference to performance in terms of the Heavy-duty FTP that would
be used for compliance for these engine standards. This is in
comparison to the steady state SET procedure that would be used for
compliance purposes for the engines used in Class 7 and 8 tractors. See
Section II.B.2.(i) above.
---------------------------------------------------------------------------

    \279\ U.S. EPA. Greenhouse Gas Emissions Standards and Fuel
Efficiency Standards for Medium- and Heavy-Duty Engines and
Vehicles--EPA Response to Comments Document for Joint Rulemaking.
EPA-420-R-11-004. Docket EPA-HQ-OAR-2010-0162.
---------------------------------------------------------------------------

    Turbochargers: Improved efficiency of a turbocharger compressor or
turbine could reduce fuel consumption by approximately 1 to 2 percent
over today's variable geometry turbochargers in the market today. The
2010 NAS report identified technologies such as higher pressure ratio
radial compressors, axial compressors, and dual stage turbochargers as
design paths to improve turbocharger efficiency.
    Low Temperature Exhaust Gas Recirculation: Most LHDD, MHDD, and
HHDD engines sold in the U.S. market today use cooled EGR, in which
part of the exhaust gas is routed through a cooler (rejecting energy to
the engine coolant) before being returned to the engine intake
manifold. EGR is a technology employed to reduce peak combustion
temperatures and thus NOX. Low-temperature EGR uses a larger
or secondary EGR cooler to achieve lower intake charge temperatures,
which tend to further reduce NOX formation. If the
NOX requirement is unchanged, low-temperature EGR can allow
changes such as more advanced injection timing that will increase
engine efficiency slightly more than one percent. Because low-
temperature EGR reduces the engine's exhaust temperature, it may not be
compatible with exhaust energy recovery systems such as
turbocompounding or a bottoming cycle.
    Engine Friction Reduction: Reduced friction in bearings, valve
trains, and the piston-to-liner interface will improve efficiency. Any
friction reduction must be carefully developed to avoid issues with
durability or performance capability. Estimates of fuel consumption
improvements due to reduced friction range from 0.5 to 1.5
percent.\280\
---------------------------------------------------------------------------

    \280\ See TIAX, Note 198, pg. 4-15.
---------------------------------------------------------------------------

    Selective catalytic reduction: This technology is common on 2010
heavy-duty diesel engines. Because SCR is a highly effective
NOX aftertreatment approach, it enables engines to be
optimized to maximize fuel efficiency, rather than minimize engine-out
NOX. 2010 SCR systems are estimated to result in improved
engine efficiency of approximately 4 to 5 percent compared to a 2007
in-cylinder EGR-based emissions system and by an even greater
percentage compared to 2010 in-cylinder approaches.\281\ As more
effective low-temperature catalysts are developed, the NOX
conversion efficiency of the SCR system will increase. Next-generation
SCR systems could then enable still further efficiency improvements;
alternatively, these advances could be used to maintain efficiency
while down-sizing the aftertreatment. We estimate that continued
optimization of the catalyst could offer 1 to 2 percent reduction in
fuel use over 2010 model year systems in the 2014 model year.\282\ The
agencies also estimate that continued refinement and optimization of
the SCR systems could provide an additional 2 percent reduction in the
2017 model year.
---------------------------------------------------------------------------

    \281\ Stanton, D. ``Advanced Diesel Engine Technology
Development for High Efficiency, Clean Combustion.'' Cummins, Inc.
Annual Progress Report 2008 Vehicle Technologies Program: Advanced
Combustion Engine Technologies, U.S. Department of Energy. Pp 113-
116. December 2008.
    \282\ See TIAX, Note 198, pg. 4-9
---------------------------------------------------------------------------

    Improved Combustion Process: Fuel consumption reductions in the
range of 1 to 4 percent are identified in the 2010 NAS report through
improved combustion chamber design, higher fuel injection pressure,
improved injection shaping and timing, and higher peak cylinder
pressures.\283\
---------------------------------------------------------------------------

    \283\ See 2010 NAS Report, Note 197, page 56.
---------------------------------------------------------------------------

    Reduced Parasitic Loads: 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.
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.\284\
---------------------------------------------------------------------------

    \284\ See TIAX. Note 198, Pages 3-5.

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

(2) What is the projected technology package's effectiveness and cost?
(a) Vocational Vehicles
(i) Baseline Vocational Vehicle Performance
    The baseline vocational vehicle model is defined in the GEM, as
described in RIA Chapter 4.4.6. At proposal, the agencies used a
baseline rolling resistance coefficient for today's vocational vehicle
fleet of 9.0 kg/metric ton.\285\ As discussed in Section II.D.1, the
agencies conducted a tire rolling resistance evaluation of tires used
in vocational vehicles. The agencies found that the average rolling
resistance of the tires was lower than the agencies' assessment at
proposal. Based on this new information and our understanding of the
potential to improve tire rolling resistance by 2014, the agencies are
setting the vocational truck standard premised on the use of tires with
a rolling resistance coefficient of 7.7 kg/metric ton. This value is
consistent with the average performance of the subset of tires the
agencies tested. We are projecting this standard will drive a 5 percent
reduction in tire rolling resistance on average across the fleet. We
are projecting this 5 percent reduction based on our expectation that
manufacturers will desire to bring all of their tires below the
standard (not just comply on average) and knowing manufacturers will
need some degree of overcompliance to ensure despite manufacturing
variability and test to test variability their products are compliant
with the emission standards. In order to reflect both this tighter
standard (based on 7.7) and the 5 percent reduction in rolling
resistance we project it will accomplish, we are modeling the baseline
performance of vocational truck tires as 8.1 kg/metric ton.
---------------------------------------------------------------------------

    \285\ The baseline tire rolling resistance for this segment of
vehicles was derived for the proposal based on the current baseline
tractor and passenger car tires. The baseline tractor drive tire has
a rolling resistance of 8.2 kg/metric ton based on SmartWay testing.
The average passenger car has a tire rolling resistance of 9.75 kg/
metric ton based on a presentation made to CARB by the Rubber
Manufacturer's Association. As noted above, further analysis has
resulted in an estimate of improved performance in the baseline
fleet, which is based entirely on use of LRR tires on vocational
vehicles (not cars). Additional details are available in the RIA
chapter 2.
---------------------------------------------------------------------------

    Further vehicle technology is not included in this baseline, as
discussed below in the discussion of the baseline vocational vehicle.
The baseline engine fuel consumption represents a 2010 model year
diesel engine, as described in RIA Chapter 4. Using these values, the
baseline performance of these vehicles is included in Table III-12.
    The agencies note that the baseline performance derived for the
final rule slightly differs from the values derived for the NPRM. The
first difference is due to the change in rolling resistance from 9.0 to
8.1 kg/metric ton based on the agencies' post-proposal test results.
Second, there are minor differences in the fuel consumption and
CO2 emissions due to the small modifications made to the
GEM, as noted in RIA Chapter 4. In addition, the HHD vocational vehicle
baseline performance for the final rule uses a revised payload
assumption from 38,000 to 15,000 pounds, as described in Section
II.D.3.c.iii.

          Table III-12--Baseline Vocational Vehicle Performance
------------------------------------------------------------------------
                                           Vocational vehicle
------------------------------------------------------------------------
                                              Medium heavy- Heavy  heavy-
                                 Heavy-duty       duty          duty
------------------------------------------------------------------------
Fuel Consumption Baseline               40.0          24.3          23.2
 (gallon/1,000 ton-mile)......
CO2 Baseline (grams CO2/ton-           408           247           236
 mile)........................
------------------------------------------------------------------------

(ii) Vocational Vehicle Technology Package
    The final program for vocational vehicles for this phase of
regulatory standards is based on the performance of tire and engine
technologies. Aerodynamics technology, weight reduction, drive train
improvement, and hybrid power trains are not included for the reasons
discussed above in Section III.C (1) and Section II.D.
    The assessment of the final technology effectiveness was developed
through the use of the GEM. To account for the two final engine
standards, EPA is finalizing the use of a 2014 model year fuel
consumption map in the GEM to derive the 2014 model year truck standard
and a 2017 model year fuel consumption map to derive the 2017 model
year truck standard. (These fuel consumption maps reflect the main
standards for HD diesel engines, not the alternative engine standards.)
The agencies estimate that the rolling resistance of 50 percent of the
tires can be reduced by 10 percent in the 2014 model year, for an
overall reduction in rolling resistance of 5 percent. The vocational
vehicle standards for all three regulatory categories were determined
using a tire rolling resistance coefficient of 7.7 kg/metric ton in the
2014 model year. The set of input parameters which are modeled in GEM
are shown in Table III-13.

                         Table III-13--GEM Inputs for Final Vocational Vehicle Standards
----------------------------------------------------------------------------------------------------------------
                                                                       2014 MY                   2017 MY
----------------------------------------------------------------------------------------------------------------
Engine......................................................   2014 MY 7L for LHD/MHD    2017 MY 7L for LHD/MHD
                                                               and 15L for HHD Trucks   and 15L for HHD Trucks.
Tire Rolling Resistance (kg/metric ton).....................                      7.7                       7.7
----------------------------------------------------------------------------------------------------------------

    The agencies developed the final standards by using the engine and
tire rolling resistance inputs in the GEM, as shown in Table III-13.
The percent reductions shown in Table III-14 reflect improvements over
the 2010 model year baseline vehicle with a 2010 model year baseline
engine.

                     Table III-14--Final Vocational Vehicle Standards and Percent Reductions
----------------------------------------------------------------------------------------------------------------
                                                                                Vocational vehicle
                                                                 -----------------------------------------------
                                                                   Light heavy-    Medium heavy-   Heavy heavy-
                                                                       duty            duty            duty
----------------------------------------------------------------------------------------------------------------
2016 MY Fuel Consumption Standard (gallon/1,000 ton-mile).......            38.1            23.0            22.2
2017 MY Fuel Consumption Standard (gallon/1,000 ton-mile).......            36.7            22.1            21.8
2014 MY CO2 Standard (grams CO2/ton-mile).......................             388             234             226
2017 MY CO2 Standard (grams CO2/ton-mile).......................             373             225             222
Percent Reduction from 2010 baseline in 2014 MY.................              5%              5%              4%
Percent Reduction from 2010 baseline in 2017 MY.................              8%              9%              6%
----------------------------------------------------------------------------------------------------------------

(iii) Technology Package Cost
    The agencies did not receive any substantial comments on the engine
costs proposed. Thus the agencies are projecting the costs of the
technologies used to develop the final standards based on the costs
used in the proposal, but revised to reflect 2009$, new ICMs, and a 50
percent penetration rate of low rolling resistance tires (as explained
above). EPA and NHTSA developed the costs of LRR tires based on the ICF
report. The estimated cost per truck is $81 (2009$) for LHD and MHD
trucks and $97 (2009$) for HHD trucks. These costs include a low
complexity ICM of 1.18 and are applicable in the 2014 model year.
(iv) Reasonableness of the Final Vocational Vehicle Standards
    The final standards would not only add only a small amount to the
vehicle cost, but are highly cost effective, an estimated $20 ton of
CO2eq per vehicle in 2030.\286\ This is even less than the
estimated cost effectiveness for CO2eq removal under the
light-duty vehicle rule, already considered by the agencies to be a
highly cost effective reduction.\287\ Moreover, the modest cost of
controls is recovered almost immediately due to the associated fuel
savings, as shown in the payback analysis included in Table VIII-7.
Given that the standards are technically feasible within the lead time
afforded by the 2014 model year, are inexpensive and highly cost
effective, and do not have other adverse potential impacts (e.g., there
are no projected negative impacts on safety or vehicle utility), the
final standards represent a reasonable choice under section 202(a) of
the CAA and NHTSA's EISA authority under 49 U.S.C. 32902(k)(2), and the
agencies believe that the standards are consistent with their
respective authorities. Based on the discussion above, NHTSA believes
these standards are the maximum feasible under EISA.
---------------------------------------------------------------------------

    \286\ See Section VIII.D.
    \287\ As noted above, the light-duty rule had an estimated cost
per ton of $50 when considering the vehicle program costs only and a
cost of -$210 per ton considering the vehicle program costs along
with fuel savings in 2030. See 75 FR 25515, Table III.H.3-1.
---------------------------------------------------------------------------

(v) Alternative Vehicle Standards Considered
    The agencies are not finalizing vehicle standards less stringent
than the final standards because the agencies believe these standards
are highly cost effective, as just explained.
    The agencies considered finalizing truck standards which are more
stringent reflecting the inclusion of hybrid powertrains in those
vocational vehicles where use of hybrid powertrains is appropriate. The
agencies estimate that a 25 percent utilization rate of hybrid
powertrains in MY 2017 vocational vehicles would add, on average,
$30,000 to the cost of each vehicle and more than double the cost of
the rule for this sector. See the RIA at chapter 6.1.8. The emission
reductions associated with these very high costs appear to be modest.
See the RIA Table 6-14. In addition, the agencies are finalizing
flexibilities in the form of generally applicable credit opportunities
for advanced technologies, to encourage use of hybrid powertrains. See
Section IV.C. 2 below. Several commenters recommended that in addition
to hybrid powertrains, the agencies consider setting more stringent
standards based on the use of aerodynamic improvements, weight
reduction, idle shutdown technologies, vehicle speed limiters, and
specific transmission technologies. As described above, we are not
finalizing standards based on these technologies for reasons that
related to the unique nature of the very diverse vocational vehicle
segment. At this time, the agencies have no means to determine the
current baseline aerodynamic performance of all vocational vehicles
(ranging from concrete mixers to school buses), nor a means to project
to what degree the aerodynamic performance could be improved without
compromising the utility of the vehicle. Absent this information, the
agencies cannot set a standard based on improvements in aerodynamic
performance. The agencies face similar obstacles regarding our ability
to project the utility tradeoffs that may exist between limitations on
vehicle speed or reductions in vehicle mass and utility and safety of
vocational vehicles. We are confident the answer to those questions
will differ for a school bus compared to a concrete mixer compared to a
fire truck compared to an ambulance. Absent an approach to set distinct
standards for each of the vocational vehicle types and the information
necessary to determine the appropriate level of performance for those
vehicles, the agencies cannot set standards for vocational vehicles
based on the use of these technologies. For these reasons, the agencies
are not adopting more comprehensive standards for vocational vehicles.
The agencies do agree that at least some vocational vehicles can be
made more efficient through the use of technologies, including those
technologies mentioned in the comments, and the agencies fully intend
to take on the challenge of developing the data, test procedures and
regulatory structures necessary to set more comprehensive standards for
vocational trucks in the future.
(b) Gasoline Engines
(i) Baseline Gasoline Engine Performance
    EPA and NHTSA developed the reference heavy-duty gasoline engines
to represent a 2010 model year engine compliant with the 0.20 g/bhp-hr
NOX standard for on-highway heavy-duty engines.
    NHTSA and EPA developed the baseline fuel consumption and
CO2 emissions for the gasoline engines from manufacturer
reported CO2 values used in the certification of non-GHG
pollutants. The baseline engine for the analysis was developed to
represent a 2011 model year engine, because this is the most current
information available. The average CO2 performance of the
heavy-duty gasoline engines was 660 g/bhp-hour, which will be used as a

baseline. The baseline gasoline engines are all stoichiometric port
fuel injected V-8 engines without cam phasers or other variable valve
timing technologies. While they may reflect some degree of static valve
timing optimization for fuel efficiency they do not reflect the
potential to adjust timing with engine speed.
(ii) Gasoline Engine Technology Package Effectiveness
    The gasoline engine technology package includes engine friction
reduction, coupled cam phasing, and SGDI to produce an overall five
percent reduction from the reference engine based on the Heavy-duty
Lumped Parameter model. The agencies are projecting a 100 percent
application rate of this technology package to the heavy-duty gasoline
engines, which results in a CO2 standard of 627 g/bhp-hr and
a fuel consumption standard of 7.05 gallon/100 bhp-hr. As discussed in
Section II.D.b.ii, the agencies are adopting gasoline engine standards
that begin in the 2016 model year based on the agencies' projection of
the engine redesign schedules for the small number of engines in this
category.
(iii) Gasoline Engine Technology Package Cost
    For the proposed costs, the agencies considered both the direct or
``piece'' costs and indirect costs of individual components of
technologies. For the direct costs, the agencies followed a BOM
approach employed by NHTSA and EPA in the light-duty 2012-2016 MY
vehicle rule. In this final action, the agencies are using marked up
gasoline engine technology costs developed for the HD Pickup Truck and
Van segment because these engines are made by the same manufacturers
(primarily by Ford and GM) and are simply, sold as loose engines rather
than as complete vehicles. Hence the engine cost estimates are
fundamentally the same. The agencies did not receive any comments
recommending adjustments to the proposed gasoline engine technology
costs. The costs summarized in Table III-15 are consistent with the
proposed values, but updated to reflect 2009$ and new ICMs. The costs
shown in Table III-15 include a low complexity ICM of 1.24 and are
applicable in the 2016 model year. No learning effects are applied to
engine friction reduction costs, while flat-portion of the curve
learning is considered applicable to both coupled cam phasing and SGDI.

 Table III-15--Heavy-Duty Gasoline Engine Technology Costs Inclusive of
                          Indirect Cost Markups
                                 [2009$]
------------------------------------------------------------------------
                                                                2016 MY
------------------------------------------------------------------------
Engine Friction Reduction....................................        $95
Coupled Cam Phasing..........................................         46
Stoichiometric Gas Direct Injection..........................        452
                                                              ----------
    Total....................................................        594
------------------------------------------------------------------------

(iv) Reasonableness of the Final Standard
    The final engine standards are reasonable and consistent with the
agencies' respective authorities. With respect to the 2016 MY standard,
all of the technologies on which the standards are predicated have been
demonstrated and their effectiveness is well documented. The final
standards reflect a 100 percent application rate for these
technologies. The costs of adding these technologies remain modest
across the various engine classes as shown in Table 0-15. Use of these
technologies would add only a small amount to the cost of the
vehicle,\288\ and the associated reductions are highly cost effective,
an estimated $20 per ton of CO2eq per vehicle.\289\ This is
even more cost effective than the estimated cost effectiveness for
CO2eq removal and fuel economy improvement under the light-
duty vehicle rule, already considered by the agencies to be a highly
cost effective reduction.\290\ Accordingly, EPA and NHTSA view these
standards as reflecting an appropriate balance of the various statutory
factors under section 202(a) of the CAA and under NHTSA's EISA
authority at 49 U.S.C. 32902(k)(2). Based on the discussion above,
NHTSA believes these standards are the maximum feasible under EISA.
---------------------------------------------------------------------------

    \288\ Sample 2010 MY vocational vehicles range in price between
$40,000 for a Class 4 work truck to approximately $200,000 for a
Class 8 refuse hauler. See pages 16-17 of ICF's ``Investigation of
Costs for Strategies to Reduce Greenhouse Gas Emissions for Heavy-
Duty On-Road Vehicles.'' July 2010.
    \289\ See Vocational Vehicle CO2 savings and
technology costs in Table 7-4 in RIA chapter 7.
    \290\ The light-duty rule had an estimated cost per ton of $50
when considering the vehicle program costs only and a cost of -$210
per ton considering the vehicle program costs along with fuel
savings in 2030. See 75 FR 25515, Table III.H.3-1.
---------------------------------------------------------------------------

    Several commenters suggested that the lead time provided by the
agencies for heavy-duty pickups and vans and by extension the 2016
gasoline engine standards were unnecessarily long. The agencies do not
agree with this assessment. The technologies that we are considering
here cannot simply be bolted on to an existing engine but can only be
effectively applied through an integrated design and development
process. The four years lead time provided here is short in the context
of engine redesigns and is only possible in part because the standards
align with engine manufacturers' planned redesign processes that are
either just starting or will be starting within the year. These
standards set a clear metric of performance for those planned redesigns
and we project will lead manufacturers to include a number of
technologies that would not otherwise have been incorporated into those
engines.
(v) Alternative Gasoline Engine Standards Considered
    The agencies are not finalizing gasoline standards less stringent
than the final standards because the agencies believe these standards
are feasible in the lead time provided, inexpensive, and highly cost
effective.
    The final rule reflects 100 percent penetration of the technology
package on whose performance the standard is based, so some additional
technology would need to be added to obtain further improvements. The
agencies considered finalizing gasoline engine standards which are more
stringent reflecting the inclusion of cylinder deactivation and other
advanced technologies. However, the agencies are not finalizing this
level of stringency because our assessment is that these technologies
cannot be adapted to the higher average engine loads of heavy-duty
vehicles for production by the 2017 model year. We intend to continue
to evaluate the potential for further gasoline engine improvements
building on the work done for light-duty passenger cars and trucks as
we begin work on the next phase of heavy-duty regulations.
(c) Diesel Engines
(i) Baseline Diesel Engine Performance
    EPA and NHTSA developed the baseline heavy-duty diesel engines to
represent a 2010 model year engine compliant with the 0.20 g/bhp-hr
NOX standard for on-highway heavy-duty engines.
    The agencies utilized 2007 through 2011 model year CO2
certification levels from the Heavy-duty FTP cycle as the basis for the
baseline engine CO2 performance. The pre-2010 data are
subsequently adjusted to represent 2010 model year engine maps by using
predefined technologies including SCR and other systems that are being
used in current 2010 production. The engine CO2 results were
then sales weighted

within each regulatory subcategory to develop an industry average 2010
model year reference engine, as shown in Table III-16. The level of
CO2 emissions and fuel consumption of these engines varies
significantly, where the engine with the highest CO2
emissions is estimated to be 20 percent greater than the sales weighted
average. Details of this analysis are included in RIA Chapter 2.

 Table III-16--2010 Model Year Reference Diesel Engine Performance Over
                        the Heavy-Duty FTP Cycle
------------------------------------------------------------------------
                               CO2 emissions  (g/     Fuel consumption
                                     bhp-hr)         (gallon/100 bhp-hr)
------------------------------------------------------------------------
LHD Diesel..................                   630                  6.19
MHD Diesel..................                   630                  6.19
HHD Diesel..................                   584                  5.74
------------------------------------------------------------------------

(ii) Diesel Engine Packages
    The diesel engine technology packages for the 2014 model year
include engine friction reduction, improved aftertreatment
effectiveness, improved combustion processes, and low temperature EGR
system optimization. The improvements in parasitic and friction losses
come through piston designs to reduce friction, improved lubrication,
and improved water pump and oil pump designs to reduce parasitic
losses. The aftertreatment improvements are available through lower
backpressure of the systems and optimization of the engine-out
NOX levels. Improvements to the EGR system and air flow
through the intake and exhaust systems, along with turbochargers can
also produce engine efficiency improvements. It should be pointed out
that individual technology improvements are not additive to each other
due to the interaction of technologies. The agencies assessed the
impact of each technology over the Heavy-duty FTP and project an
overall cycle improvement in the 2014 model year of 3 percent for HHD
diesel engines and 5 percent for LHD and MHD diesel engines, as
detailed in RIA Chapter <IP_ADDRESS> and <IP_ADDRESS>. EPA used a 100 percent
application rate of this technology package to determine the level of
the final 2014 MY standards
    Recently, EPA's heavy-duty highway engine program for criteria
pollutants provided new emissions standards for the industry in three
year increments. The heavy-duty engine manufacturer product plans have
fallen into three year cycles to reflect this environment. EPA is
finalizing CO2 emission standards recognizing the
opportunity for technology improvements over this time frame while
reflecting the typical heavy-duty engine manufacturer product plan
redesign cycles. Thus, the agencies are establishing initial standards
for the 2014 model year and a more stringent standard for these heavy-
duty engines beginning in the 2017 model year.
    The 2017 model year technology package for LHD and MHD diesel
engine includes continued development and refinement of the 2014 model
year technology package, in particular the additional improvement to
aftertreatment systems. This package leads to a projected 9 percent
reduction for LHD and MHD diesel engines in the 2017 model year. The
HHD diesel engine technology packages for the 2017 model year include
the continued development of the 2014 model year technology package. A
similar approach to evaluating the impact of individual technologies as
taken to develop the overall reduction of the 2014 model year package
was taken with the 2017 model year package. The Heavy-duty FTP cycle
improvements lead to a 5 percent reduction on the cycle for HHDD, as
detailed in RIA Chapter <IP_ADDRESS>. The agencies used a 100 percent
application rate of the technology package to determine the final 2017
MY standards. The agencies believe that bottom cycling technologies are
still in the development phase and will not be ready for production by
the 2017 model year.\291\ Therefore, these technologies were not
included in determining the stringency of the final standards. However,
we do believe the bottoming cycle approach represents a significant
opportunity to reduce fuel consumption and GHG emissions in the future
for vehicles that operate under primarily steady-state conditions like
line-haul tractors and some vocational vehicles. As discussed above, we
also considered setting standards based on the use of hybrid
powertrains that are a better match to many vocational vehicle duty
cycles but have decided for the reasons articulated above to not base
the vocational vehicle standard on the use of hybrid technologies in
this first regulation. However, EPA and NHTSA are both finalizing
provisions described in Section IV to create incentives for
manufacturers to continue to invest to develop these technologies in
the believe that with further development these technologies can form
the basis of future standards.
---------------------------------------------------------------------------

    \291\ TIAX noted in their report to the NAS panel that the
engine improvements beyond 2015 model year included in their report
are highly uncertain, though they include waste heat recovery in the
engine package for 2016 through 2020 (page 4-29).
---------------------------------------------------------------------------

    The overall projected improvements in CO2 emissions and
fuel consumption over the baseline are included in Table III-17.

 Table III-17--Percent Fuel Consumption and CO2 Emission Reductions Over
                        the Heavy-duty FTP Cycle
------------------------------------------------------------------------
                                                          2014     2017
------------------------------------------------------------------------
LHD Diesel............................................       5%       9%
MHD Diesel............................................        5        9
HHD Diesel............................................        3        5
------------------------------------------------------------------------

(iii) Technology Package Costs
    NHTSA and EPA jointly developed costs associated with the engine
technologies to assess an overall package cost for each regulatory
category. Our engine cost estimates for diesel engines used in
vocational vehicles include a separate analysis of the incremental part
costs, research and development activities, and additional equipment,
such as emissions equipment to measure N2O emissions. Our
general approach used elsewhere in this action (for HD pickup trucks,
gasoline engines, Class 7 and 8 tractors, and Class 2b-8 vocational
vehicles) estimates a direct manufacturing cost for a part and marks it
up based on a factor to account for indirect costs. See also 75 FR
25376. We believe that approach is appropriate when compliance with
final standards is achieved generally by installing new parts and
systems purchased from a supplier. In such a case, the supplier is
conducting the bulk of the research and development on the new parts
and systems and including those costs in the purchase price paid by the
original equipment manufacturer. The indirect costs incurred by the
original equipment manufacturer need not include much cost to cover
research and development since the bulk of that effort is already done.
For the MHD and

HHD diesel engine segment, however, the agencies believe we can make a
more accurate estimate of technology cost using this alternate approach
because the primary cost is not expected to be the purchase of parts or
systems from suppliers or even the production of the parts and systems,
but rather the development of the new technology by the original
equipment manufacturer itself. Therefore, the agencies believe it more
accurate to directly estimate the indirect costs. EPA commonly uses
this approach in cases where significant investments in research and
development can lead to an emission control approach that requires no
new hardware. For example, combustion optimization may significantly
reduce emissions and cost a manufacturer millions of dollars to develop
but will lead to an engine that is no more expensive to produce. Using
a bill of materials approach would suggest that the cost of the
emissions control was zero reflecting no new hardware and ignoring the
millions of dollars spent to develop the improved combustion system.
Details of the cost analysis are included in the RIA Chapter 2. To
reiterate, we have used this different approach because the MHD and HHD
diesel engines are expected to comply in large part via technology
changes that are not reflected in new hardware but rather knowledge
gained through laboratory and real world testing that allows for
improvements in control system calibrations--changes that are more
difficult to reflect through direct costs with indirect cost
multipliers.
    The agencies developed the engineering costs for the research and
development of diesel engines with lower fuel consumption and
CO2 emissions. The aggregate costs for engineering hours,
technician support, dynamometer cell time, and fabrication of prototype
parts are estimated at $6.8 million (2009$) per manufacturer per year
over the five years covering 2012 through 2016. In aggregate, this
averages out to $284 per engine during 2012 through 2016 using an
annual sales value of 600,000 light, medium, and heavy heavy-duty
engines. The agencies received comments from Horriba regarding the
assumption the agencies used in the proposal that said manufacturers
would need to purchase new equipment for measuring N2O and
the associated costs. Horriba provided information regarding the cost
of stand-alone FTIR instrumentation (estimated at $50,000 per unit) and
cost of upgrading existing emission measurement systems with NDIR
analyzers (estimated at $25,000 per unit). The agencies further
analyzed our assumptions along with Horriba's comments. Thus, we have
revised the equipment costs estimates and assumed that 75 percent of
manufacturers would update existing equipment while the other 25
percent would require new equipment. The agencies are estimating costs
of $63,087 (2009$) per engine manufacturer per engine subcategory
(light, medium, and heavy HD) to cover the cost of purchasing photo-
acoustic measurement equipment for two engine test cells. This would be
a one-time cost incurred in the year prior to implementation of the
standard (i.e., the cost would be incurred in 2013). In aggregate, this
averages out to less than $1 per engine in 2013 using an annual sales
value of 600,000 light, medium, and heavy HD engines.
    EPA also developed the incremental piece cost for the components to
meet each the 2014 and 2017 standards. These costs shown in Table III-
18 which include a low complexity ICM of 1.15; flat-portion of the
curve learning is considered applicable to each technology.

   Table III-18--Heavy-Duty Diesel Engine Component Costs Inclusive of
                         Indirect Cost Markups a
                                 [2009$]
------------------------------------------------------------------------
                                    2014 Model year     2017 Model year
------------------------------------------------------------------------
Cylinder Head (flow optimized,    $6 (MHD & HH), $11  $6 (MHD & HHD),
 increased firing pressure,        (LHD).              $10 (LHD).
 improved thermal management).
Exhaust Manifold (flow            $0................  $0.
 optimized, improved thermal
 management).
Turbocharger (improved            $18...............  $17.
 efficiency).
EGR Cooler (improved efficiency)  $4................  $3.
Water Pump (optimized, variable   $91...............  $84.
 vane, variable speed).
Oil Pump (optimized)............  $5................  $4.
Fuel Pump (higher working         $5................  $4.
 pressure, increased efficiency,
 improved pressure regulation).
Fuel Rail (higher working         $10 (MHD & HHD),    $9 (MHD & HHD),
 pressure).                        $12 (LHD).          $11 (LHD).
Fuel Injector (optimized,         $11 (MHD & HHD),    $10 (MHD & HHD),
 improved multiple event           $15 (LHD).          $13 (LHD).
 control, higher working
 pressure).
Piston (reduced friction skirt,   $3................  $3.
 ring and pin).
Aftertreatment system (improved   $0 (MHD & HHD),     $0 (MHD & HHD),
 effectiveness SCR, dosing,        $111 (LHD).         $101 (LHD).
 dpf)a.
Valve Train (reduced friction,    $82 (MHD), $109     $76 (MHD), $101
 roller tappet).                   (LHD).              (LHD).
------------------------------------------------------------------------
Note:
a Note that costs for aftertreatment improvements for MHD and HHD diesel
  engines are covered via the engineering costs (see text). For LH
  diesel engines, we have included the cost of aftertreatment
  improvements as a technology cost.

    The overall costs for each diesel engine regulatory subcategory are
included in Table III-19.

         Table III-19--Diesel Engine Technology Costs per Engine
                                 [2009$]
------------------------------------------------------------------------
                                                          2014     2017
------------------------------------------------------------------------
LHD Diesel............................................     $388     $358
MHD Diesel............................................      234      216
HHD Diesel............................................      234      216
------------------------------------------------------------------------

Reasonableness of the Final Standards
    The final engine standards appear to be reasonable and consistent
with the agencies' respective authorities. With respect to the 2014 and
2017 MY standards, all of the technologies on which the standards are
based have already been demonstrated and their effectiveness is well
documented. The final standards reflect a 100 percent application rate
for these technologies.

The costs of adding these technologies remain modest across the various
engine classes as shown in Table III-19. Use of these technologies
would add only a small amount to the cost of the vehicle,\292\ and the
associated reductions are highly cost effective, an estimated $20 per
ton of CO2eq per vehicle.\293\ This is even more cost
effective than the estimated cost effectiveness for CO2eq
removal and fuel economy improvement under the light-duty vehicle rule,
already considered by the agencies to be a highly cost effective
reduction.\294\ Accordingly, EPA and NHTSA view these standards as
reflecting an appropriate balance of the various statutory factors
under section 202(a) of the CAA and under NHTSA's EISA authority at 49
U.S.C. 32902(k)(2). Based on the discussion above, NHTSA believes these
standards are the maximum feasible under EISA.
---------------------------------------------------------------------------

    \292\ Sample 2010 MY vocational vehicles range in price between
$40,000 for a Class 4 work truck to approximately $200,000 for a
Class 8 refuse hauler. See pages 16-17 of ICF's ``Investigation of
Costs for Strategies to Reduce Greenhouse Gas Emissions for Heavy-
Duty On-Road Vehicles.'' July 2010.
    \293\ See RIA chapter 7, Table 7-4.
    \294\ The light-duty rule had a cost per ton of $50 when
considering the vehicle program costs only and a cost of -$210 per
ton considering the vehicle program costs along with fuel savings in
2030. See 75 FR 25515, Table III.H.3-1.
---------------------------------------------------------------------------

(v) Alternative Diesel Engine Standards Considered
    Other than the specific option related to legacy engine products,
the agencies are not finalizing diesel engine standards less stringent
than the final standards because the agencies believe these standards
are highly cost effective.
    The agencies have not considered finalizing diesel engine standards
which are more stringent because we have exhausted the list of engine
technologies that we believe are directly applicable to medium- and
heavy-duty diesel engines used in vocational applications. We are
continuing to evaluate the potential for bottoming cycle technologies
to be used in the future, however it is not clear today that this
technology, although promising for more steady-state operation will
provide any significant efficiency improvement under the more transient
operating cycles typical of vocational vehicles. Moreover, as stated at
II.D above, the agencies do not believe that this technology will be
available in the time frame of this rule in any case.

IV. Final Regulatory Flexibility Provisions

    This section describes flexibility provisions intended to advance
the goals of the overall program while providing alternate pathways to
achieve those goals, consistent with the agencies' statutory authority,
as well as with Executive Order 13563.\295\ The primary flexibility
provisions for combination tractors and vocational vehicles and the
engines installed in these vehicles are incorporated in a program of
averaging, banking, and trading of credits. For HD pickups and vans,
the primary flexibility provision is also an ABT program expressed in
the fleet average form of the standards, along with provisions for
credit and deficit carry-forward and for trading, patterned after the
agencies' light-duty vehicle GHG and CAFE programs. Furthermore, EPA
will allow manufacturers to comply with the N2O and
CH4 standards using CO2 credits and is providing
an opportunity for engine manufacturers to earn N2O credits
that can be used to comply with the CO2 standards. However,
EPA is not adopting an emission credit program associated with the
CH4 or HFC standards. This section also describes other
flexibility provisions that apply, including advanced technology
credits, innovative technology credits and early compliance credits.
---------------------------------------------------------------------------

    \295\ Section 4 of EO 13563 states that ``Where relevant,
feasible, and consistent with regulatory objectives, and to the
extent permitted by law, each agency shall identify and consider
regulatory approaches that reduce burdens and maintain flexibility
and freedom of choice for the public.'' 76 FR 3821 (Jan. 21, 2011).
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A. Averaging, Banking, and Trading Program

    Averaging, Banking, and Trading (ABT) of emissions credits have
been an important part of many EPA mobile source programs under CAA
Title II, including engine and vehicle programs. NHTSA has also long
had an averaging and banking program for light-duty CAFE under EPCA,
and recently gained authority to add a trading program for light-duty
CAFE through EISA. ABT programs are useful because they can help to
address many issues of technological feasibility and lead-time, as well
as considerations of cost. They provide manufacturers flexibilities
that assist the efficient development and implementation of new
technologies and therefore enable new technologies to be implemented at
a more aggressive pace than without ABT. ABT programs are more than
just add-on provisions included to help reduce costs, and can be, as in
EPA's Title II programs an integral part of the standard setting
itself. A well-designed ABT program can also provide important
environmental and energy security benefits by increasing the speed at
which new technologies can be implemented (which means that more
benefits accrue over time than with slower-starting standards) and at
the same time increase flexibility for, and reduce costs to, the
regulated industry. American Council for an Energy-Efficient Economy
(ACEEE) has commented that ABT and related flexibilities should not be
offered for this program because the agencies are not promoting the use
of new technologies but rather the use of existing technologies.
However, without ABT provisions (and other related flexibilities),
standards would typically have to be numerically less stringent since
the numerical standard would have to be adjusted to accommodate issues
of feasibility and available lead time. See 75 FR at 25412-13. By
offering ABT credits and additional flexibilities the agencies can
offer progressively more stringent standards that help meet our fuel
consumption reduction and GHG emission goals at a faster pace.
    Section II above describes EPA's GHG emission standards and NHTSA's
fuel consumption standards. For each of these respective sets of
standards, the agencies also offer ABT provisions, consistent with each
agency's statutory authority. The agencies worked closely to design
these provisions to be essentially identical to each other in form and
function. Because of this fundamental similarity, the remainder of this
section refers to these provisions collectively as ``the ABT program''
except where agency-specific distinctions are required.
    As discussed in detail below, the structure of the GHG and fuel
consumption ABT program for HD engines was based closely on EPA's
earlier ABT programs for HD engines; the program for HD pickups and
vans was built on the existing light-duty GHG program flexibility
provisions; and the first-time ABT provisions for combination tractors
and vocational vehicles are as consistent as possible with EPA's other
HD vehicle regulations. The flexibility provisions associated with this
new regulatory category were intended to build systematically upon the
structure of the existing programs.
    As an overview, ``averaging'' means the exchange of emission or
fuel consumption credits between engine families or truck families
within a given manufacturer's regulatory subcategories and averaging
sets. For example, specific ``engine families,'' which manufacturers
create by dividing their product lines into groups expected to have
similar emission characteristics throughout their useful life, would be
contained within an averaging set.

Averaging allows a manufacturer to certify one or more engine families
(or vehicle families, as appropriate) within the same averaging set at
levels worse than the applicable emission or fuel consumption standard.
The increased emissions or fuel consumption over the standard would
need to be offset by one or more engine (or vehicle) families within
that manufacturer's averaging set that are certified better than the
same emission or fuel consumption standard, such that the average
emissions or fuel consumption from all the manufacturer's engine
families, weighted by engine power, regulatory useful life, and
production volume, are at or below the level of the emission or fuel
consumption standard \296\ Total credits for each averaging set within
each model year are determined by summing together the credits
calculated for every engine family within that specific averaging set.
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    \296\ The inclusion of engine power, useful life, and production
volume in the averaging calculations allows the emissions or fuel
consumption credits or debits to be expressed in total emissions or
consumption over the useful life of the credit-using or generating
engine sales.
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    ``Banking'' means the retention of emission credits by the
manufacturer for use in future model year averaging or trading.
``Trading'' means the exchange of emission credits between
manufacturers, which can then be used for averaging purposes, banked
for future use, or traded to another manufacturer.
    In EPA's current HD engine program for criteria pollutants,
manufacturers are restricted to averaging, banking and trading only
credits generated by the engine families within a regulatory
subcategory, and EPA and NHTSA proposed to continue this restriction in
the GHG and fuel consumption program for engines and vehicles. However,
the agencies sought comment on potential alternative approaches in
which fewer restrictions are placed on the use of credits for
averaging, banking, and trading. Particularly, the agencies requested
comment on removing prohibitions on averaging and trading between some
or all regulatory categories in the proposal, and on removing
restrictions between some or all regulatory subcategories that are
within the same regulatory category (e.g., allowing trading of credits
between Class 7 day cabs and Class 8 sleeper cabs).
    The agencies received many comments on the restrictions proposed
for the ABT program, namely on the proposal that credits could only be
averaged within the specified vehicle and engine subcategories and not
averaged across subcategories or between vehicle and engine categories.
Many commenters, including Union of Concerned Scientist (UCS), NY Dept
of Transportation, Natural Resources Defense Council, Oshkosh, and
Autocar, requested that the agencies maintain the restrictions as
proposed in the NPRM. UCS argued that allowing credits to be used
across categories could undermine further technology advancements, and
that manufacturers that have broad portfolios would have advantages
over those manufacturers that do not. The Center for Biological
Diversity (CBD) argued that because of the various credit opportunities
in the ABT program and the potential that manufacturers will pay
penalties rather than comply with the standards, the program could
actually cause an increase in emissions and a decrease in fuel
efficiency. On the other hand, several commenters, including EMA/TMA,
Cummins, Volvo, and ATA, requested that the agencies maintain the
proposed restrictions of averaging credits between the engine and
vehicle categories, but reduce the restrictions on credit averaging
across vehicle subcategories or engine subcategories or averaging sets
within similar vehicle and engine weight classes (LHD, MHD and HHD).
Cummins requested that the agencies allow credit averaging between
engine subcategories within the same weight classes (LHD, MHD and HHD).
Cummins explained that tractor and vocational engines in the
corresponding weight classes not only share the same useful life but
also use the same emission and fuel consumption technologies and
therefore should be placed into the same engine averaging set. EMA/TMA
argued that the NPRM restrictions would inhibit a manufacturer's
ability to use credits to address market fluctuations, which would
reduce the flexibility that the ABT program was intended to provide. As
an example, EMA/TMA stated that if the line-haul market were depressed
for a period of time a manufacturer could make up any deficit selling
more low-roof tractors with regional hauling operations. The same
market shift could eliminate a manufacturer's ability to generate
credits using its aerodynamic high-roof sleeper cab tractors and could
create a credit deficit if there is a demand for more of the less
aerodynamic low-roof tractors. EMA/TMA argued that credit exchanges
across vehicle categories within the same weight classes within the
tractor subcategories and across vocational vehicle and tractor
subcategories would allow a manufacturer more flexibility to deal with
these types of market and customer demand situations. Finally, several
commenters, including Ford, DTNA NADA, NTEA and Navistar, requested
that the agencies reduce the proposed restrictions even further by
allowing credit averaging between vehicle categories and engine
categories. Navistar argued that more flexibility was necessary for
manufacturers like itself to increase innovation at a reasonable cost,
stating that more restrictions would increase costs within a shorter
time frame.
    After considering these comments, the agencies continue to believe
that the ABT program developed by the agencies increases and
accelerates the technological feasibility of the GHG and fuel
consumption standards by providing manufacturers flexibility in
implementing new technologies in a way that may be more consistent with
their business practices and cost considerations. In response to the
comments submitted by CBD, the agencies disagree with CBD's statements
that the ABT program will adversely affect the fuel efficiency and GHG
emission goals of this regulation. This joint final action requires
vehicle and engine manufacturers to meet increasingly more stringent
emission and fuel consumption standards which will result in emission
reductions and fuel consumption savings. Manufacturers will not have
the option of not meeting the standards. The ABT program simply
provides each manufacturer the flexibility to meet these standards
based upon their individual products and implementation plans.
    By assuming the use of credits for compliance, the agencies were
able to set the fuel consumption/GHG standards at more stringent levels
than would otherwise have been feasible. One reason is that use of ABT
allows each manufacturer maximum flexibility to develop compliance
strategies consistent with its redesign cycles and with its product
plans generally, allowing the agencies, in turn, to adopt standards
which are numerically more stringent in earlier model years than would
be possible with a more rigid program since those rigidities would be
associated with greater costs. Greater improvements in fuel efficiency
will occur under more stringent standards; manufacturers will simply
have greater flexibility to determine where and how to make those
improvements than they would have without credit options. Further, this
is consistent with the directive in EO 13563 to ``seek to identify, as
appropriate, means to

achieve regulatory goals that are designed to promote innovation.''
    The agencies further agree that certain restrictions on use of ABT
which were proposed are unnecessary. The proposed ABT program for
engines was somewhat more restrictive, in its definition of averaging
sets, than EPA's parallel ABT program for criteria pollutant emissions
from the same engines. The final rules conform to the ABT provisions
for GHG heavy-duty engine emissions to be consistent with the parallel
ABT provisions for criteria pollutants with same weight engines treated
as a single averaging set regardless of the vehicles in which they are
installed. We have applied this same principle with respect to
combination tractors and vocational vehicles: Treating like weight
classes as an averaging set. The agencies have determined that these
additional flexibilities will help to reduce manufacturing costs
further and encourage technology implementation without creating an
unfair advantage for manufactures with vertically integrated portfolios
including engines and vehicles. EPA's experience in administering the
ABT program for heavy-duty diesel engine criteria pollutant emissions
supports this conclusion. Therefore, the agencies have decided to allow
credit averaging within and across vocational vehicle and tractor
subcategories within the same weight class groups, as well as credit
averaging across the same weight class vocational and tractor engine
groups. This added flexibility beyond what was proposed in the NPRM
will not be extended to the HD pickup truck and van category because
this group of vehicles is comprised of only one subcategory and is not
broken down like the other categories and corresponding subcategories
into different weight classes, and the standard applies to the entire
vehicle, so that there are no separate engine and vehicle standards.
Put another way, the HD pickup truck and van category is one large
averaging set that will remain as proposed.
    However, the agencies are maintaining the restrictions against
averaging vehicle credits with engine credits or between vehicle weight
classes or engine subcategories for this first phase of regulation. We
believe averaging or trading credits between averaging sets would be
problematic because of the diversity of applications involved. This
diversity creates large differences in the real world conditions that
impact lifetime emissions--such as actual operating life, load cycles,