reporting of N2O and requires that manufacturers either
measure N2O or use a compliance statement based on good
engineering judgment in lieu of direct N2O measurement (74
FR 56260, October 30, 2009). The light-duty GHG final rule allows
manufacturers to provide a compliance statement based on good
engineering judgment through the 2014 model year, but requires
measurement beginning in 2015 model year (75 FR 25324, May 7, 2010).
EPA is finalizing a consistent approach for heavy-duty engine
manufacturers which allows them to delay direct measurement of
N2O until the 2015 model year.
    Manufacturers without the capability to measure N2O by
the 2015 model year would need to acquire and install appropriate
measurement equipment in response to this final program. EPA has
established four separate N2O measurement methods, all of
which are commercially available today. EPA expects that most
manufacturers would use either photo-acoustic measurement equipment for
stand-alone, existing FTIR instrumentation at a cost of $50,000 per
unit or upgrade existing emission measurement systems with NDIR
analyzers for $25,000 per test cell.
    Overall, EPA believes that manufacturers of heavy-duty engines,
both gasoline and diesel, would meet the final standard without
implementing any new technologies, and beyond relatively small
facilities costs for any company that still needs to acquire and
install N2O measurement equipment, EPA does not project that
manufacturers would incur significant costs associated with this final
N2O standard.
    EPA is not adopting any vehicle-level N2O standards for
heavy-duty vocational vehicles and combination tractors. The
N2O emissions would be controlled through the heavy-duty
engine portion of the program. The only requirement of those vehicle
manufacturers to comply with the N2O requirements is to
install a certified engine.
(2) What is EPA's approach to controlling CH4?
    CH4 is greenhouse gas with a GWP of 25. It accounts for
about 0.03 percent of the greenhouse gases from heavy-duty trucks.\179\
---------------------------------------------------------------------------

    \179\ Value adapted from ``Inventory of U.S. Greenhouse Gas
Emissions and Sinks: 1990-2007. April 2009.
---------------------------------------------------------------------------

    EPA is finalizing a standard that would cap CH4 emission
levels, with the expectation that current heavy-duty vehicles and
engines meeting the heavy-duty emission standards would not increase
their levels as explained earlier due to robust current controls and
manufacturer compliance margin targets. It would ensure that emissions
would be addressed if in the future there are increases in the use of
natural gas or any other alternative fuel. EPA believes that current
heavy-duty emission standards, specifically the NMHC standards for both
engine and chassis certified engines directly result in stringent
CH4 control. It is believed that the current emission
control technologies used to meet the stringent NMHC standards achieve
the maximum feasible reductions and that no additional technologies are
recognized that would result in additional CH4 reductions.
The level of the standard would generally be achievable through normal
emission control methods already required to meet heavy-duty emission
standards for hydrocarbons and EPA is therefore not attributing any
cost to this part of the final action. Since CH4 is produced
in gasoline and diesel engines similar to other hydrocarbon components,
controls targeted at reducing overall NMHC levels generally also work
at reducing CH4 emissions. Therefore, for gasoline and
diesel vehicles, the heavy-duty hydrocarbon standards will generally
prevent increases in CH4 emissions levels. CH4
from heavy-duty vehicles is relatively low compared to other GHGs
largely due to the high effectiveness of the current heavy-duty
standards in controlling overall HC emissions.
    EPA believes that this level for the standard would be met by
current gasoline and diesel trucks and vans, and would prevent
increases in future CH4 emissions in the event that
alternative fueled vehicles with high methane emissions, like some past
dedicated compressed natural gas vehicles, become a significant part of
the vehicle fleet. Currently EPA does not have separate CH4
standards because, unlike other hydrocarbons, CH4 does not
contribute significantly to ozone formation.\180\ However,
CH4 emissions levels in the gasoline and diesel heavy-duty
truck fleet have nevertheless

generally been controlled by the heavy-duty HC emission standards. Even
so, without an emission standard for CH4, future emission
levels of CH4 cannot be guaranteed to remain at current
levels as vehicle technologies and fuels evolve.
---------------------------------------------------------------------------

    \180\ But See Ford Motor Co. v. EPA, 604 F. 2d 685 (DC Cir.
1979) (permissible for EPA to regulate CH4 under CAA
section 202(b)).
---------------------------------------------------------------------------

    In recent model years, a small number of heavy-duty trucks and
engines were sold that were designed for dedicated use of natural gas.
While emission control designs on these recent dedicated natural gas-
fueled vehicles demonstrate CH4 control can be as effective
as on gasoline or diesel equivalent vehicles, natural gas-fueled
vehicles have historically generated significantly higher
CH4 emissions than gasoline or diesel vehicles. This is
because the fuel is predominantly methane, and most of the unburned
fuel that escapes combustion without being oxidized by the catalyst is
emitted as methane. However, even if these vehicles meet the heavy-duty
hydrocarbon standard and appear to have effective CH4
control by nature of the hydrocarbon controls, the heavy-duty standards
do not require CH4 control and therefore some natural gas
vehicle manufacturers have invested very little effort into methane
control. While the final CH4 cap standard should not require
any different emission control designs beyond what is already required
to meet heavy-duty hydrocarbon standards on a dedicated natural gas
vehicle (i.e., feedback controlled 3-way catalyst), the cap will ensure
that systems provide robust control of methane much like a gasoline-
fueled engine. We are not finalizing more stringent CH4
standards because we believe that the controls used to meet current
heavy-duty hydrocarbon standards should result in effective
CH4 control when properly implemented. Since CH4
is already measured under the current heavy-duty emissions regulations
(so that it may be subtracted to calculate NMHC), the final standard
will not result in additional testing costs.
(a) Heavy-Duty Pickup Truck and Van CH4 Standard
    EPA is finalizing the proposed CH4 emission standard of
0.05 g/mi as measured on the Light-duty FTP and HFET drive cycles, to
apply beginning with model year 2014 for HD pickups and vans subject to
the CO2 standards. Similar to the CO2 standard
approach, the CH4 emission level of a vehicle will be a
composite of the Light-duty FTP and HFET cycles, with the same 55
percent city weighting and 45 percent highway weighting.
    The level of the standard is approximately two times the average
heavy-duty gasoline and diesel truck and van levels.\181\ As with
N2O, this standard level recognizes that manufacturers
typically set emissions design targets with a compliance margin of
approximately 50 percent of the standard. Thus, we believe that the
standard should be met by current gasoline vehicles with no increase
from today's CH4 levels. Similarly, since current diesel
vehicles generally have even lower CH4 emissions than
gasoline vehicles, we believe that diesels will also meet the standard
with a larger compliance margin resulting in no change in today's
CH4 levels.
---------------------------------------------------------------------------

    \181\ Memorandum ``CH4 Data from 2010 and 2011 Heavy-
Duty Vehicle Certification Tests''.
---------------------------------------------------------------------------

(b) Heavy-Duty Engine CH4 Exhaust Emission Standard
    EPA is adopting a heavy-duty engine CH4 emission
standard of 0.10 g/hp-hr with a defined deterioration factor of 0.02 g/
bhp-hr as measured on the composite Heavy-duty FTP, to apply beginning
in model year 2014 for diesel engines and in 2016 model year for
gasoline engines. EPA is adopting a different CH4 standard
than proposed based on additional data submitted to the agency which
better represents the full range of current diesel and gasoline engine
performance. EPA is adopting CH4 standards for gasoline
engines that become effective in 2016 model year to align with the
first year of the gasoline engine CO2 standards. Without
this alignment, manufacturers would not have any flexibility, such as
CO2eq credits, in meeting the CH4 cap and
therefore would not be able to sell any engine with a CH4
level above the standard. The final standard would cap CH4
emissions at a level currently achieved by diesel and gasoline heavy-
duty engines. The level of the standard would generally be achievable
through normal emission control methods already required to meet 2007
emission standards for NMHC and EPA is therefore not attributing any
cost to this part of this program (see 40 CFR 86.007-11).
    The level of the final CH4 standard is twice the average
CH4 emissions from gasoline engines from General Motors in
addition to the four diesel engines in the ACES study.\182\ As with
N2O, this final level recognizes that manufacturers
typically set emission design targets at about 50 percent of the
standard. Thus, EPA believes the final standard would be met by current
diesel and gasoline engines with little if any technological
improvements. The agency believes a more stringent CH4
standard is not necessary due to effective CH4 controls in
current heavy-duty technologies, since, as discussed above for
N2O, EPA believes that the challenge of complying with the
CO2 standards should be the primary focus of the
manufacturers.
---------------------------------------------------------------------------

    \182\ Coordinating Research Council Report: ACES Phase 1 of the
Advanced Collaborative Emissions Study, 2009.
---------------------------------------------------------------------------

    CH4 is measured under the current 2007 regulations so
that it may be subtracted to calculate NMHC. Therefore EPA expects that
the final standard would not result in additional testing costs.
    EPA is not adopting any vehicle-level CH4 standards for
heavy-duty combination tractors or vocational vehicles in this final
action. The CH4 emissions will be controlled through the
heavy-duty engine portion of the program. The only requirement of these
truck manufacturers to comply with the CH4 requirements is
to install a certified engine.
(3) Use of CO2 Credits
    As proposed, if a manufacturer is unable to meet the N2O
or CH4 cap standards, the EPA program will allow the
manufacturer to comply using CO2 credits. In other words, a
manufacturer could offset any N2O or CH4
emissions above the standard by taking steps to further reduce
CO2. A manufacturer choosing this option would convert its
measured N2O and CH4 test results that are in
excess of the applicable standards into CO2eq to determine
the amount of CO2 credits required. For example, a
manufacturer would use 25 Mg of positive CO2 credits to
offset 1 Mg of negative CH4 credits or use 298 Mg of
positive CO2 credits to offset 1 Mg of negative
N2O credits.\183\ By using the Global Warming Potential of
N2O and CH4, the approach recognizes the inter-
correlation of these compounds in impacting global warming and is
environmentally neutral for demonstrating compliance with the
individual emissions caps. Because fuel conversion manufacturers
certifying under 40 CFR part 85, subpart F do not participate in ABT
programs, EPA is finalizing a compliance option for fuel conversion
manufacturers to comply with the N2O and CH4
standards that is similar to the credit program just described above.
The compliance option will allow conversion manufacturers, on an
individual engine family basis, to convert CO2
overcompliance into CO2 equivalents of N20 and/or
CH4 that can be subtracted from the CH4 and
N20 measured values to demonstrate compliance with
CH4 and/or N20 standards. Other than in the
limited

case of N2O for model years 2014-16, we have not finalized
similar provisions allowing overcompliance with the N2O or
CH4 standards to serve as a means to generate CO2
credits because the CH4 and N2O standards are cap
standards representing levels that all but the worst vehicles should
already be well below. Allowing credit generation against such cap
standard would provide a windfall credit without any true GHG
reduction.
---------------------------------------------------------------------------

    \183\ N2O has a GWP of 298 and CH4 has a
GWP of 25 according to the IPCC AR4.
---------------------------------------------------------------------------

    The final NHTSA fuel consumption program will not use
CO2eq, as suggested above. Measured performance to the NHTSA
fuel consumption standards will be based on the measurement of
CO2 with no adjustment for N2O and/or
CH4. For manufacturers that use the EPA alternative
CO2eq credit, compliance to the EPA CO2 standard
will not be directly equivalent to compliance with the NHTSA fuel
consumption standard.
(4) Amendment to Light-Duty Vehicle N2O and CH4
Standards
    EPA also requested comment on revising a portion of the light-duty
vehicle standards for N2O and CH4. 75 FR at
74211. Specifically, EPA requested comments on two additional options
for manufacturers to comply with N2O and CH4
standards to provide additional near-term flexibility. EPA is
finalizing one of those options, as discussed below.
    For light-duty vehicles, as part of the MY 2012-2016 rulemaking,
EPA finalized standards for N2O and CH4 which
take effect with MY 2012. 75 FR at 25421-24. Similar to the heavy-duty
standards discussed in Section II.E above, the light-duty vehicle
standards for N2O and CH4 were established to cap
emissions and to prevent future emissions increases, and were generally
not expected to result in the application of new technologies or
significant costs for the manufacturers for current vehicle designs.
EPA also finalized an alternative CO2 equivalent standard
option, which manufacturers may choose to use in lieu of complying with
the N2O and CH4 cap standards. The CO2
equivalent standard option allows manufacturers to fold all
N2O and CH4 emissions, on a CO2eq
basis, along with CO2 into their otherwise applicable
CO2 emissions standard level. For flexible fueled vehicles,
the N2O and CH4 standards must be met on both
fuels (e.g., both gasoline and E-85).
    After the light-duty standards were finalized, manufacturers raised
concerns that for a few of the vehicle models in their existing fleet
they were having difficulty meeting the N2O and/or
CH4 standards, especially in the early years of the program
for a few of the vehicle models in their existing fleet. These
standards could be problematic in the near term because there is little
lead time to implement unplanned redesigns of vehicles to meet the
standards. In such cases, manufacturers may need to either drop vehicle
models from their fleet or to comply using the CO2
equivalent alternative. On a CO2eq basis, folding in all
N2O and CH4 emissions would add 3-4 g/mile or
more to a manufacturer's overall fleet-average CO2 emissions
level because the alternative standard must be used for the entire
fleet, not just for the problem vehicles.\184\ See 75 FR at 74211. This
could be especially challenging in the early years of the program for
manufacturers with little compliance margin because there is very
limited lead time to develop strategies to address these additional
emissions. As stated at proposal, EPA believed this posed a legitimate
issue of sufficiency of lead time in the short term, as well as an
issue of cost, since EPA assumed that the N2O and
CH4 standards would not result in significant costs for
existing vehicles. Id. However, EPA expected that manufacturers would
be able to make technology changes (e.g., calibration or catalyst
changes) to the few vehicle models not currently meeting the
N2O and/or CH4 standards in the course of their
planned vehicle redesign schedules in order to meet the standards.
---------------------------------------------------------------------------

    \184\ 0.030 g/mile CH4 multiplied by a GWP of 25 plus
0.010 g/mile N2O multiplied by a GWP of 298 results in a
combined 3.7 g/mile CO2-equivalent value. Manufacturers
using the default N2O value of 0.10 g/mile prior to MY
2015 in lieu of measuring N2O would fold in the entire
0.010 g/mile on a CO2-equivalent basis, or about 3 g/mile
under the CO2-equivalent option.
---------------------------------------------------------------------------

    Because EPA intended for these standards to be caps with little
anticipated near-term impact on manufacturer's current product lines,
EPA requested comment in the heavy-duty vehicle and engine proposal on
two approaches to provide additional flexibilities in the light-duty
vehicle program for meeting the N2O and CH4
standards. 75 FR at 74211. EPA requested comments on the option of
allowing manufacturers to use the CO2 equivalent approach
for one pollutant but not the other for their fleet--that is, allowing
a manufacturer to fold in either CH4 or N2O as
part of the CO2-equivalent standard. For example, if a
manufacturer is having trouble complying with the CH4
standard but not the N2O standard, the manufacturer could
use the CO2 equivalent option including CH4, but
choose to comply separately with the applicable N2O cap
standard.
    EPA also requested comments on an alternative approach of allowing
manufacturers to use CO2 credits, on a CO2
equivalent basis, to offset N2O and CH4 emissions
above the applicable standard. This is similar to the approach proposed
and being finalized for heavy-duty vehicles as discussed above in
Section II.E. EPA requested comments on allowing the additional
flexibility in the light-duty program for MYs 2012-2014 to help
manufacturers address any near-term issues that they may have with the
N2O and CH4 standards.
    Commenters providing comment on this issue supported additional
flexibility for manufacturers, and manufacturers specifically supported
the heavy-duty vehicle approach of allowing CO2 credits on a
CO2 equivalent basis to be used to meet the CH4
and N2O standards. The Alliance of Automobile Manufacturers
and the American Automotive Policy Council commented that the proposed
heavy-duty approach represented a significant improvement over the
approach adopted for light-duty vehicles. Manufacturers support de-
linking N2O and CH4, and commented that the
formation of the pollutants do not necessarily trend together.
Manufacturers also commented that a deficit against the N2O
or CH4 cap would be required to be covered with
CO2 credits for that model, but the approach does not
``punish'' manufacturers for using a specific technology (which could
provide CO2 benefits, e.g., diesel, CNG, etc.) by requiring
manufacturers to use the CO2-equivalent approach for their
entire fleet. The Natural Gas Vehicle Interests also supported allowing
the use of CO2 credits on a CO2-equivalent basis
for compliance with CH4 standards and urged providing this
type of flexibility on a permanent basis. The Institute for Policy
Integrity also submitted comments supportive of providing additional
flexibility to manufacturers as long as it does not undermine standard
stringency. This commenter was supportive of either approach discussed
at proposal.\185\
---------------------------------------------------------------------------

    \185\ The Institute for Policy Integrity questioned whether EPA
had provided adequate notice of the proposal, given that it appeared
in the proposed GHG rules for heavy duty vehicles. EPA provided
notice not only in the preamble, but in the summary of action
appearing on the first page of the Federal Register notice (``EPA is
also requesting comment on possible alternative CO2-
equivalent approaches for model year 2012-14 light-duty vehicles'').
75 FR at 74152. This is ample notice (demonstrated as well by the
comments received on the issue, including from the Institute).
---------------------------------------------------------------------------

    Manufacturers supported not only adopting the aspects of the heavy-
duty approach noted above, but the entire

heavy-duty vehicle approach, including two aspects of the program not
contemplated in EPA's request for comments. First, manufacturers
commented that EPA incorrectly characterizes the light-duty vehicle
issues with CH4 and N2O as short-term or early
lead time issues. For the reasons discussed above, manufacturers
believe the changes should be made permanent, for the entire 2012-2016
light-duty rulemaking period and, indeed, in any subsequent rules for
the light-duty vehicle sector. Second, manufacturers commented that
N2O and CH4 should be measured on the combined
55/45 weighting of the FTP and highway cycles, respectively, as these
cycles are the yardstick for fuel economy and CO2
measurement. Manufacturers commented that there should not be a
disconnect between the light-duty and heavy-duty vehicle programs.
    EPA continues to believe that it is appropriate to provide
additional flexibility to manufacturers to meet the N2O and
CH4 standards. EPA is thus finalizing provisions allowing
manufacturers to use CO2 credits, on a CO2-
equivalent basis, to meet the N2O and CH4
standards, which is consistent with many commenters' preferred
approach. Manufacturers will have the option of using CO2
credits to meet N2O and CH4 standards on a test
group basis as needed for MYs 2012-2016. Because fuel conversion
manufacturers certifying under 40 CFR part 85, subpart F do not
participate in ABT programs, EPA is finalizing a compliance option for
fuel conversion manufacturers to comply with the N2O and
CH4 standards similar to the credit option just described
above. The compliance option will allow conversion manufacturers, on an
individual test group basis, to convert CO2 overcompliance
into CO2 equivalents of N2O and/or CH4
that can be subtracted from the CH4 and N2O
measured values to demonstrate compliance with CH4 and/or
N2O standards.
    In EPA's request for comments, EPA discussed the new flexibility as
being needed to address lead time issues for MYs 2012-2014. EPA
understands that manufacturers are now making technology decisions for
beyond MY 2014 and that some technologies such as FFVs may have
difficulty meeting the CH4 and N2O standards,
presenting manufacturers with difficult decisions of absorbing the 3-4
g/mile CO2-equivalent emissions fleet wide, making
significant investments in existing vehicle technologies, or curtailing
the use of certain technologies.\186\ The CH4 standard, in
particular, could prove challenging for FFVs because exhaust
temperatures are lower on E-85 and CH4 is more difficult to
convert over the catalyst. EPA's initial estimate that these issues
could be resolved without disrupting product plans by MY 2015 appears
to be overly optimistic, and therefore EPA is extending the flexibility
through model year 2016. This change helps ensure that the
CH4 and N2O standards will not be an obstacle for
the use of FFVs or other technologies in this timeframe, and at the
same time, assure that overall fleet average GHG emissions will remain
at the same level as under the main standards.
---------------------------------------------------------------------------

    \186\ ``Discussions with Vehicle Manufacturers Regarding the
Light-duty Vehicle CH4 and N2O Standards,''
Memorandum from Christopher Lieske to Docket EPA-HQ-OAR-2010-0162.
---------------------------------------------------------------------------

    In response to comments from manufacturers and from the Natural Gas
Vehicle Interests that the changes to the program make sense and should
be made on a permanent basis (i.e. for model years after 2016), EPA is
extending this flexibility through MY 2016 as discussed above, but we
believe it is premature to decide here whether or not these changes
should be permanent. EPA may consider this issue further in the context
of new standards for MYs 2017-2025 in the planned future light-duty
vehicle rulemaking. With regard to comments on changing the test
procedures over which N2O and CH4 emissions are
measured to determine compliance with the standards, the level of the
standards and the test procedures go hand-in-hand and must be
considered together. Weighting the highway test result with the city
test result in the emissions measurement would in most cases reduce the
overall emissions levels for determining compliance with the standards,
and would thereby, in effect make the standards less stringent. This
appears to be inappropriate. In addition, EPA did not request comments
on changing the level of the N2O and CH4
standards or the test procedures and it is inappropriate to amend the
standards for that reason as well.
(5) EPA's Final Standards for Direct Emissions From Air Conditioning
    Air conditioning systems contribute to GHG emissions in two ways--
direct emissions through refrigerant leakage and indirect exhaust
emissions due to the extra load on the vehicle's engine to provide
power to the air conditioning system. HFC refrigerants, which are
powerful GHG pollutants, can leak from the A/C system.\187\ This
includes the direct leakage of refrigerant as well as the subsequent
leakage associated with maintenance and servicing, and with disposal at
the end of the vehicle's life.\188\ The most commonly used refrigerant
in automotive applications--R134a, has a high GWP of 1430.\189\ Due to
the high GWP of R134a, a small leakage of the refrigerant has a much
greater global warming impact than a similar amount of emissions of
CO2 or other mobile source GHGs.
---------------------------------------------------------------------------

    \187\ The United States has submitted a proposal to the Montreal
Protocol which, if adopted, would phasedown production and
consumption of HFCs.
    \188\ The U.S. EPA has reclamation requirements for refrigerants
in place under Title VI of the Clean Air Act.
    \189\ The global warming potentials used in this rule are
consistent with the 2007 Intergovernmental Panel on Climate Change
(IPCC) Fourth Assessment Report. At this time, the global warming
potential values from the 1996 IPCC Second Assessment Report are
used in the official U.S. greenhouse gas inventory submission to the
United Nations Framework Convention on Climate Change (per the
reporting requirements under that international convention, which
were last updated in 2006).
---------------------------------------------------------------------------

    Heavy-duty air conditioning systems today are similar to those used
in light-duty applications. However, differences may exist in terms of
cooling capacity (such that sleeper cabs have larger cabin volumes than
day cabs), system layout (such as the number of evaporators), and the
durability requirements due to longer vehicle life. However, the
component technologies and costs to reduce direct HFC emissions are
similar between the two types of vehicles.
    The quantity of GHG refrigerant emissions from heavy-duty trucks
relative to the CO2 emissions from driving the vehicle and
moving freight is very small. Therefore, a credit approach is not
appropriate for this segment of vehicles because the value of the
credit is too small to provide sufficient incentive to utilize feasible
and cost-effective air conditioning leakage improvements. For the same
reason, including air conditioning leakage improvements within the main
standard would in many instances result in lost control opportunities.
Therefore, EPA is finalizing the proposed requirement that vehicle
manufacturers meet a low leakage requirement for all air conditioning
systems installed in 2014 model year and later trucks, with one
exception. The agency is not finalizing leakage standards for Class 2b-
8 Vocational Vehicles at this time due to the complexity in the build
process and the potential for different entities besides the chassis
manufacturer to be involved in the air conditioning system production
and installation, with

consequent difficulties in developing a regulatory system.
    For air conditioning systems with a refrigerant capacity greater
than 733 grams, EPA is finalizing a leakage standard which is a
``percent refrigerant leakage per year'' to assure that high-quality,
low-leakage components are used in each air conditioning system design.
The agency believes that a single ``gram of refrigerant leakage per
year'' would not fairly address the variety of air conditioning system
designs and layouts found in the heavy-duty truck sector. EPA is
finalizing a standard of 1.50 percent leakage per year for heavy-duty
pickup trucks and vans and Class 7 and 8 tractors. The final standard
was derived from the vehicles with the largest system refrigerant
capacity based on the Minnesota GHG Reporting database.\190\ The
average percent leakage per year of the 2010 model year vehicles is 2.7
percent. This final level of reduction is roughly comparable to that
necessary to generate credits under the light-duty vehicle program. See
75 FR 25426-25427. Since refrigerant leakage past the compressor shaft
seal is the dominant source of leakage in belt-driven air conditioning
systems, the agency recognizes that a single ``percent refrigerant
leakage per year'' is not feasible for systems with a refrigerant
capacity of 733 grams or lower, as the minimum feasible leakage rate
does not continue to drop as the capacity or size of the air
conditioning system is reduced. The fixed leakage from the compressor
seal and other system devices results in a minimum feasible yearly
leakage rate, and further reductions in refrigerant capacity (the
`denominator' in the percent refrigerant leakage calculation) will
result in a system which cannot meet the 1.50 percent leakage per year
standard. EPA does not believe that leakage reducing technologies are
available at this time which would allow lower capacity systems to meet
the percent per year standard, so we are finalizing a maximum gram per
year leakage standard of 11.0 grams per year for air conditioning
systems with a refrigerant capacity of 733 grams or lower. EPA defined
the standard, as well as the refrigerant capacity threshold, by
examining the State of Minnesota GHG Reporting Database for the yearly
leakage rate from 2010 and 2011 model year pickup trucks. In the
Minnesota data, the average leak rate for the pickup truck category (16
unique model and refrigerant capacity combinations) was 13.3 grams per
year, with an average capacity of 654 grams, resulting in an average
percent refrigerant leakage per year of 2.0 percent. 4 of the 16 model/
capacity combinations in the reporting data achieved a leak rate 11.0
grams per year or lower, and this was chosen as the maximum yearly leak
rate, as several manufacturers have demonstrated that this level of
yearly leakage is feasible. To avoid a discontinuity between the
``percent leakage'' and ``leak rate'' standards--where one approach
would be more or less stringent, depending on the refrigerant
capacity--a refrigerant capacity of 733 grams was chosen as a threshold
capacity, below which, the leak rate approach can be used. EPA believes
this approach of having a leak rate standard for lower capacity systems
and a percent leakage per year standard for higher capacity systems
will result in reduced refrigerant emissions from all air conditioning
systems, while still allowing manufacturers the ability to produce low-
leak, lower capacity systems in vehicles which require them.
---------------------------------------------------------------------------

    \190\ The Minnesota refrigerant leakage data can be found at
http://www.pca.state.mn.us/climatechange/mobileair.html#leakdata.
---------------------------------------------------------------------------

    Manufacturers can choose to reduce A/C leakage emissions in two
ways. First, they can utilize leak-tight components. Second,
manufacturers can largely eliminate the global warming impact of
leakage emissions by adopting systems that use an alternative, low-
Global Warming Potential (GWP) refrigerant. One alternative
refrigerant, HFO-1234yf, with a GWP of 4, has been approved for use in
light-duty passenger vehicles under EPA's Significant New Alternatives
Program (SNAP). While the scope of this SNAP approval does not include
heavy-duty highway vehicles, we expect that those interested in using
this refrigerant in other sectors will petition EPA for broader
approval of its use in all mobile air conditioning systems. In
addition, the EPA is currently acting on a petition to de-list R-134a
as an acceptable refrigerant for new, light-duty passenger vehicles.
The time frame and scale of R-134a de-listing is yet to be determined,
but any phase-down of R-134a use will likely take place after this
rulemaking is in effect. Given that HFO-1234yf is yet to be approved
for heavy-duty vehicles, and that the time frame for the de-listing of
R-134a is not known, EPA believes that a leakage standard for heavy-
duty vehicles is still appropriate. If future heavy-duty vehicles adopt
refrigerants other than R-134a, the calculated refrigerant leak rate
can be adjusted by multiplying the leak rate by the ratio of the GWP of
the new refrigerant divided by the GWP of the old refrigerant (e.g. for
HFO-1234yf replacing R-134a, the calculated leak rate would be
multiplied by 0.0028, or 4 divided by 1430).
    EPA believes that reducing A/C system leakage is both highly cost-
effective and technologically feasible. The availability of low leakage
components is being driven by the air conditioning program in the
light-duty GHG rule which apply to 2012 model year and later vehicles.
The cooperative industry and government Improved Mobile Air
Conditioning program has demonstrated that new-vehicle leakage
emissions can be reduced by 50 percent by reducing the number and
improving the quality of the components, fittings, seals, and hoses of
the A/C system.\191\ All of these technologies are already in
commercial use and exist on some of today's systems, and EPA does not
anticipate any significant improvements in sealing technologies for
model years beyond 2014. However, EPA has recognized some manufacturers
utilize an improved manufacturing process for air conditioning systems,
where a helium leak test is performed on 100 percent of all o-ring
fittings and connections after final assembly. By leak testing each
fitting, the manufacturer or supplier is verifying the o-ring is not
damaged during assembly (which is the primary source of leakage from o-
ring fittings), and when calculating the yearly leak rate for a system,
EPA will allow a relative emission value equivalent to a `seal washer'
can be used in place of the value normally used for an o-ring fitting,
when 100 percent helium leak testing is performed on those fittings.
While further updates to the SAE J2727 standard may be forthcoming (to
address new materials and measurement methods for permeation through
hoses), EPA believes it is appropriate to include the helium leak test
update to the leakage calculation method at this time.
---------------------------------------------------------------------------

    \191\ Team 1-Refrigerant Leakage Reduction: Final Report to
Sponsors, SAE, 2007.
---------------------------------------------------------------------------

    Consistent with the light-duty 2012-2016 MY vehicle rule, we are
estimating costs for leakage control at $18 (2008$) in direct
manufacturing costs. Including a low complexity indirect cost
multiplier (ICM) of 1.14 results in costs of $21 in the 2014 model
year. A/C control technology is considered to be on the flat portion of
the learning curve, so costs in the 2017 model year will be $19. These
costs are applied to all heavy-duty pickups and vans, and to all
combination tractors. EPA views these costs as minimal and the
reductions of potent GHGs to be easily feasible and reasonable in the
lead times provided by the final rules.

    EPA is requiring that manufacturers demonstrate improvements in
their A/C system designs and components through a design-based method.
The method for calculating A/C leakage is based closely on an industry-
consensus leakage scoring method, described below. This leakage scoring
method is correlated to experimentally-measured leakage rates from a
number of vehicles using the different available A/C components. Under
the final approach, manufacturers will choose from a menu of A/C
equipment and components used in their vehicles in order to establish
leakage scores, which will characterize their A/C system leakage
performance and calculate the percent leakage per year as this score
divided by the system refrigerant capacity.
    Consistent with the light-duty rule, EPA is finalizing a
requirement that a manufacturer will compare the components of its A/C
system with a set of leakage-reduction technologies and actions that is
based closely on that being developed through the Improved Mobile Air
Conditioning program and SAE International (as SAE Surface Vehicle
Standard J2727, ``HFC-134a, Mobile Air Conditioning System Refrigerant
Emission Chart,'' August 2008 version). See generally 75 FR 25426. The
SAE J2727 approach was developed from laboratory testing of a variety
of A/C related components, and EPA believes that the J2727 leakage
scoring system generally represents a reasonable correlation with
average real-world leakage in new vehicles. Like the cooperative
industry-government program, our final approach will associate each
component with a specific leakage rate in grams per year that is
identical to the values in J2727 and then sum together the component
leakage values to develop the total A/C system leakage. However, in the
heavy-duty vehicle program, the total A/C leakage score will then be
divided by the value of the total refrigerant system capacity to
develop a percent leakage per year. EPA believes that the design-based
approach will result in estimates of likely leakage emissions
reductions that will be comparable to those that would eventually
result from performance-based testing.
    EPA is not specifying a specific in-use standard for leakage, as
neither test procedures nor facilities exist to measure refrigerant
leakage from a vehicle's air conditioning system. However, consistent
with the light-duty rule, where we require that manufacturers attest to
the durability of components and systems used to meet the
CO2 standards (see 75 FR 25689), we will require that
manufacturers of heavy-duty vehicles attest to the durability of these
systems, and provide an engineering analysis which demonstrates
component and system durability.
(6) Indirect Emissions From Air Conditioning
    In addition to direct emissions from refrigerant leakage, air
conditioning systems also create indirect exhaust emissions due to the
extra load on the vehicle's engine to provide power to the air
conditioning system. These indirect emissions are in the form of the
additional CO2 emitted from the engine when A/C is being
used due to the added loads. Unlike direct emissions which tend to be a
set annual leak rate not directly tied to usage, indirect emissions are
fully a function of A/C usage.
    These indirect CO2 emissions are associated with air
conditioner efficiency, since air conditioners create load on the
engine. See 74 FR 49529. However, the agencies are not setting air
conditioning efficiency standards for vocational vehicles, combination
tractors, or heavy-duty pickup trucks and vans. The CO2
emissions due to air conditioning systems in these heavy-duty vehicles
are minimal compared to their overall emissions of CO2. For
example, EPA conducted modeling of a Class 8 sleeper cab using the GEM
to evaluate the impact of air conditioning and found that it leads to
approximately 1 gram of CO2/ton-mile. Therefore, a projected
24 percent improvement of the air conditioning system (the level
projected in the light-duty GHG rulemaking), would only reduce
CO2 emissions by less than 0.3 g CO2/ton-mile, or
approximately 0.3 percent of the baseline Class 8 sleeper cab
CO2 emissions.
(7) Ethanol-Fueled and Electric Vehicles
    Current EPA emissions control regulations explicitly apply to
heavy-duty engines and vehicles fueled by gasoline, methanol, natural
gas and liquefied petroleum gas. For multi-fueled vehicles they call
for compliance with requirements established for each consumed fuel.
This contrasts with EPA's light-duty vehicle regulations that apply to
all vehicles generally, regardless of fuel type. As we proposed, we are
revising the heavy-duty vehicle and engine regulations to make them
consistent with the light-duty vehicle approach, applying standards for
all regulated criteria pollutants and GHGs regardless of fuel type,
including application to all-electric vehicles (EVs). This provision
will take effect in the 2014 model year, and be optional for
manufacturers in earlier model years. However, to satisfy the CAA
section 202(a)(3) lead time constraints, the provision will remain
optional for all criteria pollutants through the 2015 model year.
Commenters did not oppose this change in EPA regulations.
    This change primarily affects manufacturers of ethanol-fueled
vehicles (designed to operate on fuels containing at least 50 percent
ethanol) and EVs. Flex-fueled vehicles (FFVs) designed to run on both
gasoline and fuel blends with high ethanol content will also be
impacted, as they will need to comply with requirements for operation
both on gasoline and ethanol.
    The regulatory requirements we are finalizing today for
certification on ethanol follow those already established for methanol,
such as certification to NMHC equivalent standards and waiver of
certain requirements. We expect testing to be done using the same E85
test fuel as is used today for light-duty vehicle testing, an 85/15
blend of commercially-available ethanol and gasoline vehicle test fuel.
EV certification will also follow light-duty precedents, primarily
calling on manufacturers to exercise good engineering judgment in
applying the regulatory requirements, but will not be allowed to
generate NOX or PM credits.
    This provision is not expected to result in any significant added
burden or cost. It is already the practice of HD FFV manufacturers to
voluntarily conduct emissions testing for these vehicles on E85 and
submit the results as part of their certification application, along
with gasoline test fuel results. No changes in certification fees are
being set in connection with this provision. We expect that there will
be strong incentives for any manufacturer seeking to market these
vehicles to also want them to be certified: (1) Uncertified vehicles
carry a disincentive to potential purchasers who typically have the
benefit to the environment as one of their reasons for considering
alternative fuels, (2) uncertified vehicles are not eligible for the
substantial credits they could likely otherwise generate, (3) EVs have
no tailpipe or evaporative emissions and thus need no added hardware to
put them in a certifiable configuration, and (4) emissions controls for
gasoline vehicles and FFVs are also effective on dedicated ethanol-
fueled vehicles, and thus costly development programs and specialized
components will not be needed; in fact the highly integrated nature of
modern automotive products make the emission control systems essential
to reliable vehicle performance.

    Regarding technological feasibility, as mentioned above, HD FFV
manufacturers already test on E85 and the resulting data shows that
they can meet emissions standards on this fuel. Furthermore, there is a
substantial body of certification data on light-duty FFVs (for which
testing on ethanol is already a requirement), showing existing emission
control technology is capable of meeting even the more stringent Tier 2
standards in place for light-duty vehicles.
(8) Correction to 40 CFR 1033.625
    In a 2008 final rule that set new locomotive and marine engine
standards, EPA adopted a provision allowing manufacturers to use a
limited number of nonroad engines to power switch locomotives provided,
among other things, that ``the engines were certified to standards that
are numerically lower than the applicable locomotive standards of this
part (1033).'' (40 CFR 1033.625(a)). The goal of this provision is to
encourage the replacement of aging, high-emitting switch locomotives
with new switch locomotives having very low emissions of PM,
NOX, and hydrocarbons. However, this provision neglected to
consider the fact that preexisting nonroad engine emission standards
for CO were set at levels that were slightly numerically higher than
those for locomotives. The applicable switch locomotive CO standard of
part 1033 is 3.2 g/kW-hr (2.4 g/hp-hr), while the applicable nonroad
engine CO standard is 3.5 g/kW-hr (2.6 g/hp-hr). This is the case even
for the cleanest final Tier 4 nonroad engines that will phase in
starting in 2014. Thus, nonroad engines cannot be certified to CO
standards that are numerically lower than the applicable locomotive
standards, and the nonroad engine provision is rendered practically
unusable. This matter was brought to EPA's attention by affected engine
manufacturers.\192\
---------------------------------------------------------------------------

    \192\ See e-mail correspondence from Timothy A. French, EMA, to
Donald Kopinski and Charles Moulis, U.S. EPA dated 12/8/10,
``Switcher Locomotive Flexibility'', docket  EPA-HQ-OAR-
2010-0162.
---------------------------------------------------------------------------

    As indicated above, EPA believes that allowing certification of new
switch locomotive engines to nonroad engine standards will greatly
reduce emissions from switch locomotives, and EPA does not believe the
slight difference in CO standards should prevent this environmentally
beneficial program. EPA is therefore adopting a corrective technical
amendment in part 1033. The regulation is being amended at Sec.
1033.625(a)(2) to add the following italicized text: ``The engines were
certified to PM, NOX, and hydrocarbon standards that are
numerically lower than the applicable locomotive standards of this
part.'' This change is a straightforward correction to restore the
intended usability of the provision and is not expected to have adverse
environmental impacts, as nonroad engines have CO emissions that are
typically well below both the nonroad and locomotive emissions
standards.
(9) Corrections to 40 CFR Part 600
    EPA adopted changes to fuel economy labeling requirements on July
6, 2011 (76 FR 39478). We are making the following corrections to these
regulations in 40 CFR part 600:
     We adopted a requirement to use the specifications of SAE
J1711 for fuel economy testing related to hybrid-electric vehicles. In
this final rule, we are extending that requirement to the calculation
provisions in Sec.  600.114-12. This change was inadvertently omitted
from the earlier final rule.
     We are correcting an equation in Sec.  600.116-12.
     We are removing text describing label content that differs
from the sample labels that were published with the final rule. The
sample labels properly characterize the intended label content.
(10) Definition of Urban Bus
    EPA is adding a new section 86.012-2 to revise the definition of
``urban bus.'' The new definition will treat engines used in urban
buses the same as engines used in any other HD vehicle application,
relying on the definitions of primary intended service class for
defining which standards and useful life apply for bus engines. This
change is necessary to allow for installation of engines other than
HHDDE for hybrid bus applications.

III. Feasibility Assessments and Conclusions

    In this section, NHTSA and EPA discuss several aspects of our joint
technical analyses. These analyses are common to the development of
each agency's final standards. Specifically we discuss: the development
of the baseline used by each agency for assessing costs, benefits, and
other impacts of the standards, the technologies the agencies evaluated
and their costs and effectiveness, and the development of the final
standards based on application of technology in light of the attribute
based distinctions and related compliance measurement procedures. We
also discuss the agencies' consideration of standards that are either
more or less stringent than those adopted.
    This program is based on the need to obtain significant oil savings
and GHG emissions reductions from the transportation sector, and the
recognition that there are appropriate and cost-effective technologies
to achieve such reductions feasibly in the model years of this program.
The decision on what standard to set is guided by each agency's
statutory requirements, and is largely based on the need for
reductions, the effectiveness of the emissions control technology, the
cost and other impacts of implementing the technology, and the lead
time needed for manufacturers to employ the control technology. The
availability of technology to achieve reductions and the cost and other
aspects of this technology are therefore a central focus of this final
rulemaking.
    CBD submitted several comments on whether NHTSA had met EISA's
mandate to set standards ``designed to achieve the maximum feasible
improvement'' and, to that end, appropriately considered feasible
technologies in setting the stringency level. CBD stated that the
proposed rule had been improperly limited to currently available
technology, and that none of the alternatives contained all of the
available technology, which it argued violated EISA and the CAA. CBD
also stated that the phase-in schedule violated the technology-forcing
intention of EISA, and that the agencies misperceived their statutory
mandates, arguing that the agencies are required to force technological
innovation through aggressive standards.
    As demonstrated in the standard-specific discussions later in this
section of the preamble, the standards adopted in the final program are
consistent with section 202(a) of the CAA and section 32902(k)(2) of
EISA. With respect to the EPA rules, we note at the outset, that CBD's
premise that EPA must adopt ``technology-forcing'' standards for heavy-
duty vehicles and engines is wrong. A technology-forcing standard is
one that is to be based on standards which will be available, rather
than technology which is presently available. NRDC v. Thomas, 805 F. 2d
410, 429 (DC Cir. 1986). Clean Air Act provisions requiring ``the
greatest degree of emission reduction achievable through the
application of technology which the Administrator determines will be
available'' are technology-forcing. See e.g., CAA sections
202(a)(3)(1);\193\

213(a)(3). Section 202(a)(1) standards are technology-based, but not
technology-forcing, requiring EPA to issue standards for a vehicle's
useful life ``after providing such period as the Administrator finds
necessary to permit the development and application of the requisite
technology, giving appropriate consideration to the cost of compliance
within such period.'' See NACAA v. EPA, 489 F. 3d 1221, 1230 (DC Cir.
2007) upholding EPA's interpretation of similar language in CAA section
231(a) as providing even greater leeway to weigh the statutory factors
than if the provision were technology-forcing. See generally 74 FR at
49464-465 (Sept. 28. 2009); 75 FR at 74171.
---------------------------------------------------------------------------

    \193\ CBD cites the District Court's opinion in Cent. Valley
Chrysler-Jeep Inc. v. Goldstene, 529 F. Supp. 2d 1151, 1178 (E.D.
Cal. 2007) for the proposition that standard-setting provisions of
Title II of the CAA are technology forcing, but the court was citing
to the technology-forcing provision section 202(a)(3)(A)(i), which
is not the applicable authority here.
---------------------------------------------------------------------------

    Section 202(a)(1) of course allows EPA to consider application of
technologies which will be available as well as those presently
available, id., and EPA exercised that discretion here. For example, as
shown below, the agencies carefully considered application of hybrid
technologies and bottoming cycle technologies for a number of the
standards. Thus, the critical issue is whether EPA's choice of
technology penetration on which the standards are premised is
reasonable considering the statutory factors, the key ones being
technology feasibility, technology availability in the 2014-2018 model
years (i.e., adequacy of lead time), and technology cost and cost-
effectiveness. EPA has considerable discretion to weigh these factors
in a reasonable manner (even for provisions which are explicitly
technology-forcing, see Sierra Club v. EPA, 325 F. 3d 374, 378 (DC Cir.
2003)), and has done so here.
    With respect to EISA, 49 U.S.C. section 32902(k)(2) directs NHTSA
to ``determine in a rulemaking proceeding how to implement a commercial
medium- and heavy-duty on-highway vehicle and work truck fuel
efficiency improvement program designed to achieve the maximum feasible
improvement,'' and ``adopt and implement appropriate test methods,
measurement metrics, fuel economy standards, and compliance and
enforcement protocols that are appropriate, cost-effective, and
technologically feasible for commercial medium- and heavy-duty on-
highway vehicles and work trucks'' NHTSA recognizes that Congress
intended EPCA (and by extension, EISA, which amended it) to be
technology-forcing. See Center for Auto Safety v. National Highway
Traffic Safety Admin., 793 F.2d 1322, 1339 (DC Cir. 1986). However,
NHTSA believes it is important to distinguish between setting ``maximum
feasible'' standards, as EPCA/EISA requires, and ``maximum
technologically feasible'' standards, as CBD would have NHTSA do. The
agency must weigh all of the statutory factors in setting fuel
efficiency standards, and therefore may not weigh one statutory factor
in isolation of others.
    Neither EPCA nor EISA define ``maximum feasible'' in the context of
setting fuel efficiency or fuel economy standards. Instead, NHTSA is
directed to consider and meet three factors when determining what the
maximum feasible standards are--``appropriateness, cost-effectiveness,
and technological feasibility.'' 32902(k)(2). These factors modify
``feasible'' in the context of the MD/HD rules beyond a plain meaning
of ``capable of being done.'' See Center for Biological Diversity v.
National Highway Traffic Safety Admin., 538 F.3d 1172, 1194 (9th Cir.
2008). With respect to the setting of standards for light-duty
vehicles, EPCA/EISA ``gives NHTSA discretion to decide how to balance
the statutory factors--as long as NHTSA's balancing does not undermine
the fundamental purpose of EPCA: energy conservation.'' Id. at 1195.
Where Congress has not directly spoken to a potential issue related to
such a balancing, NHTSA's interpretation must be a ``reasonable
accommodation of conflicting policies * * * committed to the agency's
care by the statute.'' Id. (discussing consideration of consumer
demand) (internal citations omitted). In the context of the agency's
light-duty vehicle authority, it was determined that Congress delegated
the process for setting the maximum feasible standard to NHTSA with
broad guidelines concerning the factors that the agency must consider.
Id. (internal citations omitted) (emphasis in original). We believe
that the same conclusion should be drawn about the statutory provisions
governing the agency's setting of standards for heavy-duty vehicles.
Those provisions prescribe statutory factors commensurate to, and
equally broad as, those prescribed for light-duty. Thus, NHTSA believes
that it is firmly within our discretion to weigh and balance the
factors laid out in 32902(k) in a way that is technology-forcing, as
evidenced by these standards promulgated in this final action, but not
in a way that requires the application of technology which will not be
available in the lead time provided by the rules, or which is not cost-
effective, or is cost-prohibitive, as CBD evidently deems mandated.
    As detailed below for each regulatory category, NHTSA has
considered the appropriateness, cost-effectiveness, and technological
feasibility of the standards in designing a program to achieve the
maximum feasible fuel efficiency improvement. It believes that each of
those criteria is met.
    As described in Section I. F. (2) above, the final standards will
remain in effect indefinitely at their 2018 or 2019 levels, unless and
until the standards are revised. CBD maintained that this is a per se
violation of EISA, arguing that, by definition, standards which are not
updated continually and regularly cannot be considered maximum
feasible. NHTSA would like to clarify that the NPRM specified that the
standards would remain indefinitely ``until amended by a future
rulemaking action.'' NPRM at 74172. Further, as noted above, NHTSA has
broad discretion to determine the maximum feasible standards. Unlike
Sec.  32902(b)(3)(B), which applies to automobiles regulated under
light-duty CAFE, Sec.  32902(k) does not specify a maximum number of
years that fuel economy standards for heavy-duty vehicles will be in
place. Consistent with its broad authority to define maximum feasible
standards, NHTSA interprets its authority as including the discretion
to define expiration periods where Congress has not otherwise
specified. This is particularly appropriate for the heavy-duty sector,
where fuel efficiency regulation is unprecedented. NHTSA believes that
it would be unwise to set an expiration period for this first
rulemaking absent both Congressional direction and a known compelling
reason for setting a specific date.
    NHTSA believes that the phase-in schedules provide an appropriate
balance between the technology-forcing purpose of the statute and EISA-
mandated considerations of economic practicability. NHTSA recognizes,
as noted in the case above, that balancing each statutory factor in
order to set the maximum feasible standards means that the agency must
engage in a ``reasonable accommodation of conflicting policies.'' See
538 F.3d at 1195, supra. Here, the agency has determined that the
phase-in schedules are one such reasonable accommodation.
    Navistar commented generally that the proposed rule was not
technologically feasible, stating that the proposed standards assume
technologies which are not in production for all manufacturers. This is

not the test for technical feasibility. Under the Clean Air Act, EPA
needs only to outline a technical path toward compliance with a
standard, giving plausible reasons for its belief that technology will
either be developed or applied in the requisite period. NRDC v. EPA,
655 F. 2d 318, 333-34 (DC Cir. 1981). EPA has done so here with respect
to the alternative engine standards of particular concern to
Navistar.\194\ Similarly, NHTSA has previously interpreted
``technological feasibility'' to mean ``whether a particular method of
improving fuel economy can be available for commercial application in
the model year for which a standard is being established.'' 74 FR
14196, 14216. NHTSA has further clarified that the consideration of
technological feasibility ``does not mean that the technology must be
available or in use when a standard is proposed or issued.'' Center for
Auto Safety v. National Highway Traffic Safety Admin., 793 F.2d 1322,
1325 n12 (DC Cir. 1986), quoting 42 FR 63, 184, 63, 188 (1977).
---------------------------------------------------------------------------

    \194\ See 40 CFR 1036.620.
---------------------------------------------------------------------------

    Consistent with these previous interpretations, NHTSA believes that
a technology does not necessarily need to be currently available or in
use for all regulated parties to be ``technologically feasible'' for
this program, as long as it is reasonable to expect, based on the
evidence before the agency, that the technology will be available in
the model year in which the relevant standard takes effect. The
agencies provide multiple technology pathways for compliance with a
standard, allowing each manufacturer to develop technologies which fit
their current production and research, and the standards are based on
fleet penetration rates of those technologies. As discussed below, it
is reasonable to assume that all the technologies on whose performance
the standards are premised will be available over the period the
standards are in effect.
    The Institute for Policy Integrity (IPI) commented that the
agencies should increase the scope and stringency of the final rule to
the point at which net benefits would be maximized, citing Executive
Orders 12866 and 13563. EOs 12866 and 13563 instruct agencies, to the
extent permitted by law, to select, among other things, the regulatory
approaches which maximize net benefits. NHTSA agrees with IPI about the
applicability of these EOs and has made every effort to incorporate
their guidance in drafting this rule.
    Though IPI agreed that the proposed rule was cost-benefit
justified, IPI further stated that the agencies must implement an
alternative that provides the maximum net benefits. The agencies
believe that standards that maximized net benefits would be beyond the
point of technological feasibility for this first phase of the HD
National Program. The standards already require the maximum feasible
fuel efficiency improvements for the HD fleet in the 2014-2018 time
frame. Thus, even though, the final standards are highly cost-
effective, and standards that maximized net benefits would likely be
more stringent than those being promulgated in this final action, NHTSA
believes that standards that maximized net benefits would not be
appropriate or technologically feasible in the rulemaking time frame.
The Executive Orders cited by IPI cannot and do not require an agency
to select a regulatory alternative that is inconsistent with its
statutory obligations. Thus, the standards adopted in the final rules
are consistent with the agencies' respective statutory authorities, and
are not established at levels which are infeasible or cost-ineffective.
    Here, the focus of the standards is on applying fuel efficiency and
emissions control technology to reduce fuel consumption, CO2
and other greenhouse gases. Vehicles combust fuel to generate power
that is used to perform two basic functions: (1) Transport the truck
and its payload, and (2) operate various accessories during the
operation of the truck such as the PTO units. Engine-based technology
can reduce fuel consumption and CO2 emissions by improving
engine efficiency, which increases the amount of power produced per
unit of fuel consumed. Vehicle-based technology can reduce fuel
consumption and CO2 emissions by increasing the vehicle
efficiency, which reduces the amount of power demanded from the engine
to perform the truck's primary functions.
    Our technical work has therefore focused on both engine efficiency
improvements and vehicle efficiency improvements. In addition to fuel
delivery, combustion, and aftertreatment technology, any aspect of the
truck that affects the need for the engine to produce power must also
be considered. For example, the drag due to aerodynamics and the
resistance of the tires to rolling both have major impacts on the
amount of power demanded of the engine while operating the vehicle.
    The large number of possible technologies to consider and the
breadth of vehicle systems that are affected mean that consideration of
the manufacturer's design and production process plays a major role in
developing the final standards. Engine and vehicle manufacturers
typically develop many different models based on a limited number of
platforms. The platform typically consists of a common engine or truck
model architecture. For example, a common engine platform may contain
the same configuration (such as inline), number of cylinders,
valvetrain architecture (such as overhead valve), cylinder head design,
piston design, among other attributes. An engine platform may have
different calibrations, such as different power ratings, and different
aftertreatment control strategies, such as exhaust gas recirculation
(EGR) or selective catalytic reduction (SCR). On the other hand, a
common vehicle platform has different meanings depending on the market.
In the heavy-duty pickup truck market, each truck manufacturer usually
has only a single pickup truck platform (for example the F series by
Ford) with common chassis designs and shared body panels, but with
variations on load capacity of the axles, the cab configuration, tire
offerings, and powertrain options. Lastly, the combination tractor
market has several different platforms and the trucks within each
platform (such as LoneStar by Navistar) have less commonality. Tractor
manufacturers will offer several different options for bumpers,
mirrors, aerodynamic fairing, wheels, and tires, among others. However,
some areas such as the overall basic aerodynamic design (such as the
grill, hood, windshield, and doors) of the tractor are tied to tractor
platform.
    The platform approach allows for efficient use of design and
manufacturing resources. Given the very large investment put into
designing and producing each truck model, manufacturers of heavy-duty
pickup trucks and vans typically plan on a major redesign for the
models every 5 years or more (a key consideration in the choice of the
five model year duration during which the vehicle standards are phased
in). Recently, EPA's non-GHG heavy-duty engine program provided new
emissions standards every three model years. Heavy-duty engine and
truck manufacturer product plans typically have fallen into three year
cycles to reflect this regime. While the recent non-GHG emissions
standards can be handled generally with redesigns of engines and
trucks, a complete redesign of a new heavy-duty engine or truck
typically occurs on a slower cycle and often does not align in time due
to the fact that the manufacturer of engines

differs from the truck manufacturer. At the redesign stage, the
manufacturer will upgrade or add all of the technology and make most
other changes supporting the manufacturer's plans for the next several
years, including plans related to emissions, fuel efficiency, and
safety regulations.
    A redesign of either engine or truck platforms often involves a
package of changes designed to work together to meet the various
requirements and plans for the model for several model years after the
redesign. This often involves significant engineering, development,
manufacturing, and marketing resources to create a new product with
multiple new features. In order to leverage this significant upfront
investment, manufacturers plan vehicle redesigns with several model
years of production in mind. Vehicle models are not completely static
between redesigns as limited changes are often incorporated for each
model year. This interim process is called a refresh of the vehicle and
it generally does not allow for major technology changes although more
minor ones can be done (e.g., small aerodynamic improvements, etc).
More major technology upgrades that affect multiple systems of the
vehicle thus occur at the vehicle redesign stage and not in the time
period between redesigns.
    As discussed below, there are a wide variety of CO2 and
fuel consumption reducing technologies involving several different
systems in the engine and vehicle that are available for consideration.
Many can involve major changes to the engine or vehicle, such as
changes to the engine block and cylinder heads or changes in vehicle
shape to improve aerodynamic efficiency. Incorporation of such
technologies during the periodic engine, transmission or vehicle
redesign process would allow manufacturers to develop appropriate
packages of technology upgrades that combine technologies in ways that
work together and fit with the overall goals of the redesign. By
synchronizing with their multi-year planning process, manufacturers can
avoid the large increase in resources and costs that would occur if
technology had to be added outside of the redesign process. We
considered redesign cycles both in our costing and in assessing needed
the lead time required.
    As described below, the vast majority of technology on whose
performance the final standards are predicated is commercially
available and already being utilized to a limited extent across the
heavy-duty fleet. Therefore the majority of the emission and fuel
consumption reductions which would result from these final rules would
result from the increased use of these technologies. EPA and NHTSA also
believe that these final rules will encourage the development and
limited use of more advanced technologies, such as advanced
aerodynamics and hybrid powertrains in some vocational vehicle
applications.
    In evaluating truck efficiency, NHTSA and EPA have excluded
consideration of standards which could result in fundamental changes in
the engine or vehicle's performance. Put another way, none of the
technology pathways underlying the final standards involve any
alteration in vehicle utility. For example, the agencies did not
consider approaches that would necessitate reductions in engine power
or otherwise limit truck performance. The agencies have thus limited
the assessment of technical feasibility and resultant vehicle cost to
technologies which maintain freight utility. Similarly, the agencies'
choice of attributes on which to base the standards, and the metrics
used to measure them, are consciously adopted to preserve the utility
of heavy-duty vehicles and engines.
    The agencies worked together to determine component costs for each
of the technologies and build up the costs accordingly. For 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 bill of materials approach utilized by the
agencies in the light-duty 2012-16 MY vehicle rule. A bill of
materials, in a general sense, is a list of components or sub-systems
that make up a system--in this case, an item of technology which
reduces GHG emissions and fuel consumption. In order to determine what
a system costs, one of the first steps is to determine its components
and what they cost. NHTSA and EPA estimated these components and their
costs based on a number of sources for cost-related information. In
general, the direct costs of fuel consumption-improving technologies
for heavy-duty pickups and vans are consistent with those used in the
light-duty 2012-2016 MY vehicle rule, except that the agencies have
scaled up certain costs where appropriate to accommodate the larger
size and/or loads placed on parts and systems in the heavy-duty classes
relative to the light-duty classes. For loose heavy-duty engines, the
agencies have consulted various studies and have exercised engineering
judgment when estimating direct costs. For technologies expected to be
added to vocational vehicles and combination tractors, the agencies
have again consulted various studies and have used engineering judgment
to arrive at direct cost estimates. Once costs were determined, they
were adjusted to ensure that they were all expressed in 2009 dollars
using a ratio of gross domestic product deflators for the associated
calendar years.
    Indirect costs were accounted for using the ICM approach explained
in Chapter 2 of the RIA, rather than using the traditional Retail Price
Equivalent (RPE) multiplier approach. For the heavy-duty pickup truck
and van cost projections in this final action, the agencies have used
ICMs developed for light-duty vehicles (with the exception that here
return on capital has been incorporated into the ICMs, where it had not
been in the light-duty rule) primarily because the manufacturers
involved in this segment of the heavy-duty market are the same
manufacturers that build light-duty trucks. For the Class 7 and 8
tractor, vocational vehicle, and heavy-duty engine cost projections in
this final rulemaking, EPA contracted with RTI International to update
EPA's methodology for accounting for indirect costs associated with
changes in direct manufacturing costs for heavy-duty engine and truck
manufacturers.\195\ In addition to the indirect cost multipliers
varying by complexity and time frame, there is no reason to expect that
the multipliers would be the same for engine manufacturers as for truck
manufacturers. The report from RTI provides a description of the
methodology, as well as calculations of new indirect cost multipliers.
The multipliers used here include a factor of 5 percent of direct costs
representing the return on capital for heavy-duty engines and truck
manufacturers. These indirect cost multipliers are intended to be used,
along with calculations of direct manufacturing costs, to provide
improved estimates of the full additional costs associated with new
technologies. The agencies did not receive any adverse comments related
to this methodology.
---------------------------------------------------------------------------

    \195\ RTI International. Heavy-duty Truck Retail Price
Equivalent and Indirect Cost Multipliers. July 2010.
---------------------------------------------------------------------------

    Details of the direct and indirect costs, and all applicable ICMs,
are presented in Chapter 2 of the RIA. In addition, for details on the
ICMs, please refer to the RTI report (See Docket ID EPA-HQ-OAR-2010-
0162-0283). Importantly, the agencies have revised the ICM factors and
the way that indirect costs are calculated using the ICMs. As a result,
the ICM factors are now higher, the indirect costs are higher and,
therefore, technology costs are

higher. The changes made to the ICMs and the indirect cost calculations
are discussed in Section VIII of this preamble and are detailed in
Chapter 2 of the RIA.
    EPA and NHTSA believe that the emissions reductions called for by
the final standards are technologically feasible at reasonable costs
within the lead time provided by the final standards, reflecting our
projections of widespread use of commercially available technology.
Manufacturers may also find additional means to reduce emissions and
lower fuel consumption beyond the technical approaches we describe
here. We encourage such innovation through provisions in our
flexibility program as discussed in Section IV.
    The remainder of this section describes the technical feasibility
and cost analysis in greater detail. Further detail on all of these
issues can be found in the joint RIA Chapter 2.

A. Class 7-8 Combination Tractor

    Class 7 and 8 tractors are used in combination with trailers to
transport freight.\196\ The variation in the design of these tractors
and their typical uses drive different technology solutions for each
regulatory subcategory. The agencies are adopting provisions to treat
vocational tractors as vocational vehicles instead of as combination
tractors, as noted in Section II.B. The focus of this section is on the
feasibility of the standards for combination tractors, not the
vocational tractors.
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    \196\ ``Tractor'' is defined in 49 CFR 571.3 to mean ``a truck
designed primarily for drawing other motor vehicles and not so
constructed as to carry a load other than a part of the weight of
the vehicle and the load so drawn.''
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    EPA and NHTSA collected information on the cost and effectiveness
of fuel consumption and CO2 emission reducing technologies
from several sources. The primary sources of information were the 2010
National Academy of Sciences report of Technologies and Approaches to
Reducing the Fuel Consumption of Medium- and Heavy-Duty Vehicles,\197\
TIAX's assessment of technologies to support the NAS panel report,\198\
EPA's Heavy-duty Lumped Parameter Model,\199\ the analysis conducted by
the Northeast States Center for a Clean Air Future, International
Council on Clean Transportation, Southwest Research Institute and TIAX
for reducing fuel consumption of heavy-duty long haul combination
tractors (the NESCCAF/ICCT study),\200\ and the technology cost
analysis conducted by ICF for EPA.\201\ Following on the EISA of 2007,
the National Research Council appointed a NAS committee to assess
technologies for improving fuel efficiency of heavy-duty vehicles to
support NHTSA's rulemaking. The 2010 NAS report assessed current and
future technologies for reducing fuel consumption, how the technologies
could be implemented, and identified the potential cost of such
technologies. The NAS panel contracted with TIAX to perform an
assessment of technologies which provide potential fuel consumption
reductions in heavy-duty trucks and engines and the technologies'
associated capital costs. Similar to the Lumped Parameter model which
EPA developed to assess the impact and interactions of GHG and fuel
consumption reducing technologies for light-duty vehicles, EPA
developed a new version of that model to specifically address the
effectiveness and interactions of the final pickup truck and light
heavy-duty engine technologies. The NESCAFF/ICCT study assessed
technologies available in 2012 through 2017 to reduce CO2
emissions and fuel consumption of line haul combination tractors and
trailers. Lastly, the ICF report focused on the capital, maintenance,
and operating costs of technologies currently available to reduce
CO2 emissions and fuel consumption in heavy-duty engines,
combination tractors, and vocational vehicles.
---------------------------------------------------------------------------

    \197\ Committee to Assess Fuel Economy Technologies for Medium-
and Heavy-Duty Vehicles; National Research Council; Transportation
Research Board (2010). Technologies and Approaches to Reducing the
Fuel Consumption of Medium- and Heavy-Duty Vehicles. (``The NAS
Report'') Washington, DC, The National Academies Press. Available
electronically from the National Academy Press Web site at http://www.nap.edu/catalog.php?record_id=12845.
    \198\ TIAX, LLC. ``Assessment of Fuel Economy Technologies for
Medium- and Heavy-Duty Vehicles,'' Final Report to National Academy
of Sciences, November 19, 2009.
    \199\ U.S. EPA. Heavy-duty Lumped Parameter Model.
    \200\ NESCCAF, ICCT, Southwest Research Institute, and TIAX.
Reducing Heavy-Duty Long Haul Combination Truck Fuel Consumption and
CO2 Emissions. October 2009.
    \201\ ICF International. ``Investigation of Costs for Strategies
to Reduce Greenhouse Gas Emissions for Heavy-Duty On-Road
Vehicles.'' July 2010. Docket Number EPA-HQ-OAR-2010-0162-0283.
---------------------------------------------------------------------------

(1) What technologies did the agencies consider to reduce the
CO2 emissions and fuel consumption of combination tractors?
    Manufacturers can reduce CO2 emissions and fuel
consumption of combination tractors through use of, among others,
engine, aerodynamic, tire, extended idle, and weight reduction
technologies. The standards in the final rules are premised on use of
these technologies. The agencies note that SmartWay trucks are
available today which incorporate the technologies on whose performance
the final standards are based. We will also discuss other technologies
that could potentially be used, such as vehicle speed limiters,
although we are not basing the final standards on their use for the
model years covered by this rulemaking, for various reasons discussed
below.
    In this section we discuss the baseline tractor and engine
technologies for the 2010 model year, and then discuss the types of
technologies that the agencies considered to improve performance
relative to this baseline, while Section III.A.2 discusses the
technology packages the agencies used to determine the final standard
levels.
(a) Baseline Tractor & Tractor Technologies
    Baseline tractor: The agencies developed the baseline tractor to
represent the average 2010 model year tractor. Today there is a large
spread in aerodynamics in the new tractor fleet. Trucks sold may
reflect so-called classic styling (as described in Section II.B.3.c),
or may be sold with aerodynamic packages. Based on our review of
current truck model configurations and Polk data provided through MJ
Bradley,\202\ we believe the aerodynamic configuration of the baseline
new truck fleet is approximately 25 percent Bin I, 70 percent Bin II,
and 5 percent Bin III (as these bin configurations are explained above
in Section II.B. (2)(c). The baseline Class 7 and 8 day cab tractor
consists of an aerodynamic package which closely resembles the Bin I
package described in Section II.B. (2)(c), baseline tire rolling
resistance of 7.8 kg/metric ton for the steer tire and 8.2 kg/metric
ton,\203\ dual tires with steel wheels on the drive axles, and no
vehicle speed limiter. The baseline tractor for the Class 8 sleeper
cabs contains the same aerodynamic and tire rolling resistance
technologies as the baseline day cab, does not include vehicle speed
limiters, and does not include an idle reduction technology. The
agencies assume the baseline transmission is a 10 speed manual. The
agencies received a comment from the ICCT stating that the 0.69 Cd
baseline for high roof sleepers published in the NPRM is higher than
existing studies show. ICCT cited three studies

including a Society of Automotive Engineering paper showing a lower Cd
for tractor trailers. The agencies based the average Cd for high roof
sleepers on available in use fleet composition data, combined with an
assessment of drag coefficient for different truck configurations. The
agencies are finalizing the 0.69 baseline Cd for high roof sleeper
based on our assessment for the NPRM. However, we will continue to
gather information on the composition of the in-use fleet and may alter
the baseline in a future action, should more data become available that
demonstrates our estimate is incorrect.
---------------------------------------------------------------------------

    \202\ MJ Bradley. Heavy-duty Market Analysis. May 2009. Page 10.
    \203\ U.S. Environmental Protection Agency. SmartWay Transport
Partnership July 2010 e-update accessed July 16, 2010, from http://www.epa.gov/smartwaylogistics/newsroom/documents/e-update-july-10.pdf.
---------------------------------------------------------------------------

    Performance from this baseline can be improved by the use of the
following technologies:
    Aerodynamic technologies: There are opportunities to reduce
aerodynamic drag from the tractor, but it is difficult to assess the
benefit of individual aerodynamic features. Therefore, reducing
aerodynamic drag requires optimizing of the entire system. The
potential areas to reduce drag include all sides of the truck--front,
sides, top, rear and bottom. The grill, bumper, and hood can be
designed to minimize the pressure created by the front of the truck.
Technologies such as aerodynamic mirrors and fuel tank fairings can
reduce the surface area perpendicular to the wind and provide a smooth
surface to minimize disruptions of the air flow. Roof fairings provide
a transition to move the air smoothly over the tractor and trailer.
Side extenders can minimize the air entrapped in the gap between the
tractor and trailer. Lastly, underbelly treatments can manage the flow
of air underneath the tractor. As discussed in the TIAX report, the
coefficient of drag (Cd) of a SmartWay sleeper cab high roof tractor is
approximately 0.60, which is a significant improvement over a truck
with no aerodynamic features which has a Cd value of approximately
0.80.\204\ The GEM demonstrates that an aerodynamic improvement of a
Class 8 high roof sleeper cab with a Cd value of 0.60 (which represents
a Bin III tractor) provides a 5 percent reduction in fuel consumption
and CO2 emissions over a truck with a Cd of 0.68.
---------------------------------------------------------------------------

    \204\ See TIAX, Note 198, Page 4-50.
---------------------------------------------------------------------------

    Lower Rolling Resistance Tires: A tire's rolling resistance results
from the tread compound material, the architecture and materials of the
casing, tread design, the tire manufacturing process, and its operating
conditions (surface, inflation pressure, speed, temperature, etc.).
Differences in rolling resistance of up to 50 percent have been
identified for tires designed to equip the same vehicle. The baseline
rolling resistance coefficient for today's fleet is 7.8 kg/metric ton
for the steer tire and 8.2 kg/metric ton for the drive tire, based on
sales weighting of the top three manufacturers based on market
share.\205\ Since 2007, SmartWay trucks have had steer tires with
rolling resistance coefficients of less than 6.6 kg/metric ton for the
steer tire and less than 7.0 kg/metric ton for the drive tire.\206\ Low
rolling resistance (LRR) drive tires are currently offered in both dual
assembly and single wide-base configurations. Single wide tires can
offer rolling resistance reduction along with improved aerodynamics and
weight reduction. The GEM demonstrates that replacing baseline tractor
tires with tires which meet the Bin I level provides approximately a 4
percent reduction in fuel consumption and CO2 emissions over
the prescribed test cycle, as shown in RIA Chapter 2, Figure 2-2.
---------------------------------------------------------------------------

    \205\ See SmartWay, Note 203, above.
    \206\ Ibid.
---------------------------------------------------------------------------

    Weight Reduction: Reductions in vehicle mass reduce fuel
consumption and GHGs by reducing the overall vehicle mass to be
accelerated and also through increased vehicle payloads which can allow
additional tons to be carried by fewer trucks consuming less fuel and
producing lower emissions on a ton-mile basis. Initially for proposal,
the agencies considered evaluating vehicle mass reductions on a total
vehicle basis for combination tractors.\207\ The agencies considered
defining a baseline vehicle curb weight and the GEM would have used the
vehicle's actual curb weight to calculate the increase or decrease in
fuel consumption related to the overall vehicle mass relative to that
baseline. After considerable evaluation of this issue, including
discussions with the industry, we decided it would not be possible to
define a single vehicle baseline mass for the tractors that would be
appropriate and representative. Actual vehicle curb weights for these
classes of vehicles vary by thousands of pounds dependent on customer
features added to vehicles and critical to the function of the vehicle
in the particular vocation in which it is used. This is true of
vehicles such as Class 8 tractors considered in this section that may
appear to be relatively homogenous but which in fact are quite
heterogeneous.
---------------------------------------------------------------------------

    \207\ The agencies are using the approach of evaluating total
vehicle mass for heavy-duty pickups and vans where we have more data
on the current fleet vehicle mass.
---------------------------------------------------------------------------

    This reality led us to the solution we proposed. In the proposal,
we reflected mass reductions for specific technology substitutions
(e.g., installing aluminum wheels instead of steel wheels) where we
could with confidence verify the mass reduction information provided by
the manufacturer even though we cannot estimate the actual curb weight
of the vehicle. In this way, we accounted for mass reductions where we
can accurately account for its benefits.
    For the final rules, based on evaluation of the comments, the
agencies developed an expanded list of weight reduction opportunities,
from which the sum of the weight reduction from the technologies
installed on a specific tractor can be input into the GEM as listed in
Table II-9 in Section II. The list includes additional components, but
not materials, from those proposed in the NPRM. For high strength
steel, the weight reduction value is equal to 10 percent of the
presumed baseline component weight, as the agencies used a conservative
value based on the DOE report. We recognize that there may be
additional potential for weight reduction in new high strength steel
components which combine the reduction due to the material substitution
along with improvements in redesign, as evidenced by the studies done
for light-duty vehicles. In the development of the high strength steel
component weights, we are only assuming a reduction from material
substitution and no weight reduction from redesign, since we do not
have any data specific to redesign of heavy-duty components nor do we
have a regulatory mechanism to differentiate between material
substitution and improved design. We are finalizing for wheels that
both aluminum and light weight aluminum are eligible to be used as
light-weight materials. Only aluminum and not light weight aluminum can
be used as a light-weight material for other components. The reason for
this is data was available for light weight aluminum for wheels but was
not available for other components.
    As explained in Section II.B above, the agencies continue to
believe that the 400 pound weight target is appropriate for setting the
final combination tractor CO2 emissions and fuel consumption
standards. The agencies agree with the commenter that 400 pounds of
weight reduction without the use of single wide tires may not be
achievable for all tractor configurations. The agencies have expanded
the list of weight reduction components which can be input into the GEM
in order to provide the manufacturers with additional means to comply
with the combination tractors and to further encourage reductions in
vehicle weight. The agencies considered increasing the

target value beyond 400 pounds given the additional reduction potential
identified in the expanded technology list; however, lacking
information on the capacity for the industry to change to these light
weight components across the board by the 2014 model year, we have
decided to maintain the 400 pound target. The agencies intend to
continue to study the potential for additional weight reductions in our
future work considering a second phase of truck fuel efficiency and GHG
regulations.
    A weight reduction of 400 pounds applied to a truck which travels
at 70,000 pounds will have a minimal impact on fuel consumption.
However, for trucks which operate at the maximum GVWR which occurs
approximately in one third of truck miles travelled, a reduced tare
weight will allow for additional payload to be carried. The GEM
demonstrates that a weight reduction of 400 pounds applied to the
payload tons for one third of the trips provides a 0.3 percent
reduction in fuel consumption and CO2 emissions over the
prescribed test cycle, as shown in Figure 2-3 of RIA Chapter 2.
    Extended Idle Reduction: Auxiliary power units (APU)s, fuel
operated heaters, battery supplied air conditioning, and thermal
storage systems are among the technologies available today to reduce
main engine extended idling from sleeper cabs. Each of these
technologies reduces the baseline fuel consumption during idling from a
truck without this equipment (the baseline) from approximately 0.8
gallons per hour (main engine idling fuel consumption rate) to
approximately 0.2 gallons per hour for an APU.\208\ EPA and NHTSA agree
with the TIAX assessment of a 6 percent reduction in overall fuel
consumption reduction.\209\
---------------------------------------------------------------------------

    \208\ See the RIA Chapter 2 for details.
    \209\ See the 2010 NAS Report, Note 197, above, at 128.
---------------------------------------------------------------------------

    Vehicle Speed Limiters: Fuel consumption and GHG emissions increase
proportional to the square of vehicle speed. Therefore, lowering
vehicle speeds can significantly reduce fuel consumption and GHG
emissions. A vehicle speed limiter (VSL), which limits the vehicle's
maximum speed, is a simple technology that is utilized today by some
fleets (though the typical maximum speed setting is often higher than
65 mph). The GEM shows that using a vehicle speed limiter set at 62 mph
on a sleeper cab tractor will provide a 4 percent reduction in fuel
consumption and CO2 emissions over the prescribed test
cycles over a baseline vehicle without a VSL or one set above 65
mph.\210\
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    \210\ The Center for Biological Diversity thought that the
agencies; were limiting their consideration of vehicle speed
limiters as a potential control technology due to perceived legal
constraints. As noted above, vehicle speed limiters are a potential
control technology for heavy duty vehicles and there is no statutory
bar on either agency considering the performance of VSLs in
developing the standards.
---------------------------------------------------------------------------

    Transmission: As discussed in the 2010 NAS report, automatic and
automated manual transmissions may offer the ability to improve vehicle
fuel consumption by optimizing gear selection compared to an average
driver. However, as also noted in the report and in the supporting TIAX
report, the improvement is very dependent on the driver of the truck,
such that reductions ranged from 0 to 8 percent.\211\ Well-trained
drivers would be expected to perform as well or even better than an
automatic transmission since the driver can see the road ahead and
anticipate a changing stoplight or other road condition that an
automatic transmission can not anticipate. However, poorly-trained
drivers that shift too frequently or not frequently enough to maintain
optimum engine operating conditions could be expected to realize
improved in-use fuel consumption by switching from a manual
transmission to an automatic or automated manual transmission. Although
we believe there may be real benefits in reduced fuel consumption and
GHG emissions through the application of dual clutch, automatic or
automated manual transmission technology, we are not reflecting this
potential improvement in our standard setting or in our compliance
model. We have taken this approach because we cannot say with
confidence what level of performance improvement to expect.
---------------------------------------------------------------------------

    \211\ See TIAX, Note 198, above at 4-70.
---------------------------------------------------------------------------

    Low Friction Transmission, Axle, and Wheel Bearing Lubricants: The
2010 NAS report assessed low friction lubricants for the drivetrain as
a 1 percent improvement in fuel consumption based on fleet
testing.\212\ The light-duty 2012-16 MY vehicle rule and the pickup
truck portion of this program estimate that low friction lubricants can
have an effectiveness value between 0 and 1 percent compared to
traditional lubricants. However, it is not clear if in many heavy-duty
applications these low friction lubricants could have competing
requirements like component durability issues requiring specific
lubricants with different properties than low friction.
---------------------------------------------------------------------------

    \212\ See the 2010 NAS Report, Note 197, page 67.
---------------------------------------------------------------------------

    Hybrid: Hybrid powertrain development in Class 7 and 8 tractors has
been limited to a few manufacturer demonstration vehicles to date. One
of the key benefit opportunities for fuel consumption reduction with
hybrids is less fuel consumption when a vehicle is idling, but the
standard is already premised on use of extended idle reduction so use
of hybrid technology would duplicate many of the same emission
reductions attributable to extended idle reduction. NAS estimated that
hybrid systems would cost approximately $25,000 per tractor in the 2015
through the 2020 time frame and provide a potential fuel consumption
reduction of 10 percent, of which 6 percent is idle reduction which can
be achieved (less expensively) through the use of other idle reduction
technologies.\213\ The limited reduction potential outside of idle
reduction for Class 8 sleeper cab tractors is due to the mostly highway
operation and limited start-stop operation. Due to the high cost and
limited benefit during the model years at issue in this action (as well
as issues regarding sufficiency of lead time (see Section III.2 (a)
below), the agencies are not including hybrids in assessing standard
stringency (or as an input to GEM). However as discussed in Section IV,
the agencies are providing incentives to encourage the introduction of
advanced technologies including hybrid powertrains in appropriate
applications.
---------------------------------------------------------------------------

    \213\ See the 2010 NAS Report, Note 197, page 128.
---------------------------------------------------------------------------

    Management: The 2010 NAS report noted many operational
opportunities to reduce fuel consumption, such as driver training and
route optimization. The agencies have included discussion of several of
these strategies in RIA Chapter 2, but are not using these approaches
or technologies in the standard setting process. The agencies are
looking to other resources, such as EPA's SmartWay Transport
Partnership and regulations that could potentially be promulgated by
the Federal Highway Administration and the Federal Motor Carrier Safety
Administration, to continue to encourage the development and
utilization of these approaches.
(b) Baseline Engine & Engine Technologies
    The baseline engine for the Class 8 tractors is a Heavy Heavy-Duty
Diesel engine with 15 liters of displacement which produces 455
horsepower. The agencies are using a smaller baseline engine for the
Class 7 tractors because of the lower combined weights of this class of
vehicles require less power, thus the baseline is an 11L engine with
350 horsepower. The agencies

developed the baseline diesel engine as a 2010 model year engine with
an aftertreatment system which meets EPA's 0.20 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 baseline engine is turbocharged with a
variable geometry turbocharger. 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.A.2.6
below.
    With respect to stringency level, the agencies received comments
from Cummins and Daimler stating that the proposed stringency levels
were appropriate for the lead-times. Conversely, the agencies received
comments from several environmental groups (UCS, CATF, ACEEE)
supporting a greater reduction in engine CO2 emissions and
fuel consumption based on the NAS report. Navistar also stated that the
agencies' baseline engine is inappropriate since there is not currently
a 0.20 NOX compliant engine in production. A discussion of
how the baseline engine configuration can be found below in Section
(2)(b)(i).
    Navistar also stated that the baseline engines proposed in the
NPRM, MY 2010 selective catalytic reduction (SCR)-equipped, could not
meet the agencies' statutory obligation to set feasible standards, and
requested instead that MY 2010 engines currently in-use be used to meet
the feasibility factor. The agencies thus disagree with the statement
that SCR is infeasible and therefore, the agencies reaffirm that the
engine used as the baseline engine in the agencies' analysis does
indeed exist. In fact, several engine families have been certified by
EPA using SCR technology over the past two years, all of which have met
the 0.20 g/bhp-hr NOX standard.\214\ EPA disagrees with
Navistar that SCR engines currently certified do not meet this
standard. Compliance with the 0.20 g/bhp-hr FTP NOX standard
is measured based on an engine's performance when tested over a
specific duty cycle (see 40 CFR 86.007-11(a)(2)). This is also true
regarding the SET standard (see 40 CFR 86.007-11(a)(3)). Further, the
FTP and SET tests are average tests, so emissions could go over 0.20
even for some portion of the test itself. Manufacturers are also
required to ensure that their engines meet the NTE standard under all
conditions specified in the regulations (see 40 CFR 86.007-11(a)(4)).
---------------------------------------------------------------------------

    \214\ See 2010 Model Year Engine Certification Data and 2011
Model Year Engine Certification Data files located in the Docket
EPA-HQ-OAR-2010-0162.
---------------------------------------------------------------------------

    Several manufacturers have been able to show compliance with these
standards in applications for certification provided to EPA for several
engine families. Navistar has provided no information indicating that
these tests were false or improper. Indeed, Navistar does not appear to
suggest, or provide any evidence, that engines with working SCR systems
do not meet the NOX standard. Thus, it is demonstrably false
to conclude that the NOX standard cannot be met with SCR-
equipped engines.
    A more detailed response to these comments appears in Section 6.2
of the Response to Comment document for this rule.
    Engine performance for CO2 emissions and fuel
consumption can be improved by use of the following technologies:
    Improved Combustion Process: Fuel consumption reductions in the
range of 1 to 3 percent over the baseline diesel engine 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.\215\
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    \215\ See TIAX. Note 198, Page 4-13.
---------------------------------------------------------------------------

    Turbochargers: Improved efficiency of a turbocharger compressor or
turbine could reduce fuel consumption by approximately 1 to 2 percent
over variable geometry turbochargers in the market today.\216\ 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.
---------------------------------------------------------------------------

    \216\ See TIAX Note 198, Page 4-2.
---------------------------------------------------------------------------

    Higher efficiency air handling processes: To maximize the
efficiency of such processes, induction systems may be improved by
manufacturing more efficiently designed flow paths (including those
associated with air cleaners, chambers, conduit, mass air flow sensors
and intake manifolds) and by designing such systems for improved
thermal control. Improved turbocharging and air handling systems must
include higher efficiency EGR systems and intercoolers that reduce
frictional pressure loss while maximizing the ability to thermally
control induction air and EGR. The agencies received comments from
Honeywell confirming that turbochargers provide a role in reducing the
CO2 emissions from engines. Other components that offer
opportunities for improved flow efficiency include cylinder heads,
ports and exhaust manifolds to further reduce pumping losses. Variable
air breathing systems such as variable valve actuation may provide
additional gains at different loads and speeds. The NESCCAF/ICCT study
indicated up to 1.2 percent reduction could be achieved solely through
improved EGR systems.
    Low Temperature Exhaust Gas Recirculation: Most medium- and heavy-
duty vehicle diesel 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 1 percent.\217\ 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.
---------------------------------------------------------------------------

    \217\ See TIAX, Note 198, Page 4-13.
---------------------------------------------------------------------------

    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 to 2 percent.\218\
---------------------------------------------------------------------------

    \218\ TIAX, Note 198, pg 4-15
---------------------------------------------------------------------------

    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.\219\ Bendix, in their comments to the agencies, confirmed
that there are engine accessories available that can improve an
engine's fuel efficiency.
---------------------------------------------------------------------------

    \219\ See TIAX. Note 198, Page 3-5.
---------------------------------------------------------------------------

    Selective catalytic reduction: This technology is common on 2010
the medium- and heavy-duty diesel engines used in Class 7 and 8
tractors (and the agencies therefore have included it as part of the
baseline engine, as noted above). 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 3 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.\220\ 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 additional 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.\221\ The
agencies estimate an additional 1 to 2 percent reduction may be
feasible in the 2017 model year through additional refinement.
---------------------------------------------------------------------------

    \220\ 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.
    \221\ See TIAX, Note 198, pg. 4-9.
---------------------------------------------------------------------------

    Mechanical Turbocompounding: Mechanical turbocompounding adds a low
pressure power turbine to the exhaust stream in order to extract
additional energy, which is then delivered to the crankshaft. Published
information on the fuel consumption reduction from mechanical
turbocompounding varies between 2.5 and 5 percent.\222\ Some of these
differences may depend on the operating condition or duty cycle that
was considered by the different researchers. The performance of a
turbocompounding system tends to be highest at full load and much less
or even zero at light load.
---------------------------------------------------------------------------

    \222\ NESCCAF/ICCT study (p. 54) and TIAX (2009, pp. 3-5).
---------------------------------------------------------------------------

    Electric Turbocompounding: This approach is similar in concept to
mechanical turbocompounding, except that the power turbine drives an
electrical generator. The electricity produced can be used to power an
electrical motor supplementing the engine output, to power electrified
accessories, or to charge a hybrid system battery. None of these
systems have been demonstrated commercially, but modeled results by
industry and DOE have shown improvements of 3 to 5 percent.\223\
---------------------------------------------------------------------------

    \223\ K. G. Duleep of Energy and Environmental Analysis, R.
Kruiswyk, 2008, pp. 212-214, NESCCAF/ICCT, 2009, p. 54.
---------------------------------------------------------------------------

    Bottoming Cycle: An engine with bottoming cycle uses exhaust or
other heat energy from the engine to create power without the use of
additional fuel. The sources of energy include the exhaust, EGR, charge
air, and coolant. The estimates for fuel consumption reduction range up
to 10 percent as documented in the 2010 NAS report.\224\ However, none
of the bottoming cycle or Rankine systems has been demonstrated
commercially and are currently in only the research stage. See Section
<IP_ADDRESS> of the RIA and Section II.B above.
---------------------------------------------------------------------------

    \224\ See 2010 NAS Report, Note 197, page 57.
---------------------------------------------------------------------------

(2) Projected Technology Package Effectiveness and Cost
(a) Class 7 and 8 Combination Tractors
    EPA and NHTSA project that CO2 emissions and fuel
consumption reductions can be feasibly and cost-effectively achieved in
these rules' time frames through the increased application of
aerodynamic technologies, LRR tires, weight reduction, extended idle
reduction technologies, vehicle speed limiters, and engine
improvements. The agencies believe that hybrid powertrains systems for
tractors will not be sufficiently developed and the necessary
manufacturing capacity put in place to base a standard on any
significant volume of hybrid tractors. The agencies are not aware of
any full hybrid systems currently developed for long haul tractor
applications. To date, hybrid systems for tractors have been primarily
focused on idle shutdown technologies and not the broader energy
storage and recovery systems necessary to achieve reductions over
typical vehicle drive cycles. The final standards reflect the potential
for idle shutdown technologies through the GEM model. Further as
highlighted by the 2010 NAS report, the agencies do believe that full
hybrid powertrains have the potential in the longer term to provide
significant improvements in fuel efficiency and to reduce greenhouse
gas emissions. However lacking any existing systems or manufacturing
base, we cannot conclude such technology will be available in the 2014-
2018 timeframe. Developing a full hybrid system itself would be a three
to five project followed by several more years to put in place
manufacturing capacity. The agencies are including incentives for the
use of hybrid technologies to help encourage their development and to
reward manufacturers that can produce hybrids through prototype and low
volume production methods. The agencies also are not including
drivetrain technologies in the standard setting process, as discussed
in Section II.B.3.h.iv.
    The agencies evaluated each technology and estimated the most
appropriate application rate of technology into each tractor
subcategory. The next sections describe the effectiveness of the
individual technologies, the costs of the technologies, the projected
application rates of the technologies into the regulatory
subcategories, and finally the derivation of the final standards.
(i) Baseline Tractor Performance
    The agencies developed the baseline tractor for each subcategory to
represent an average 2010 model year tractor configured as noted
earlier. The approach taken by the agencies was to define the
individual inputs to the GEM, as shown in Table III-1. For example, the
agencies evaluated the industry's tractor offerings and concluded that
the average tractor contains a generally aerodynamic shape (such as
roof fairings) and avoids classic features such as an exhaust stacks at
the B-pillar, which increases drag. As noted earlier, our assessment of
the baseline new high roof tractor fleet aerodynamics consists of
approximately 25 percent Bin I, 70 percent Bin II, and 5 percent Bin
III tractors. The baseline rolling resistance coefficient for today's
fleet is 7.8 kg/metric ton for the steer tire and 8.2 kg/metric ton for
the drive tire, based on sales weighting of the top three

manufacturers based on market share.\225\ The agencies assumed no
application of vehicle speed limiters, weight reduction technologies,
or idle reduction technologies in the baseline tractor. The agencies
use the inputs in the GEM to derive the baseline CO2
emissions and fuel consumption of Class 7 and 8 tractors. The results
are included in Table III-1.
---------------------------------------------------------------------------

    \225\ U.S. Environmental Protection Agency. SmartWay Transport
Partnership July 2010 e-update accessed July 16, 2010, from http://www.epa.gov/smartwaylogistics/newsroom/documents/e-update-july-10.pdf.

                                                        Table III-1--Baseline Tractor Definitions
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                    Class 7                                                    Class 8
                                    --------------------------------------------------------------------------------------------------------------------
                                                    Day cab                                Day cab                              Sleeper cab
                                    --------------------------------------------------------------------------------------------------------------------
                                       Low roof     Mid roof    High roof     Low roof     Mid roof    High roof     Low roof     Mid roof    High roof
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                    Aerodynamics (Cd)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Baseline...........................         0.77         0.87         0.73         0.77         0.87         0.73         0.77         0.87         0.70
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                             Steer Tires (CRR kg/metric ton)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Baseline...........................          7.8          7.8          7.8          7.8          7.8          7.8          7.8          7.8          7.8
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                             Drive Tires (CRR kg/metric ton)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Baseline...........................          8.2          8.2          8.2          8.2          8.2          8.2          8.2          8.2          8.2
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                  Weight Reduction (lb)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Baseline...........................            0            0            0            0            0            0            0            0            0
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                  Extended Idle Reduction (gram CO2/ton-mile reduction)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Baseline...........................          N/A          N/A          N/A          N/A          N/A          N/A            0            0            0
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                  Vehicle Speed Limiter
--------------------------------------------------------------------------------------------------------------------------------------------------------
Baseline...........................  ...........  ...........  ...........  ...........  ...........  ...........  ...........  ...........  ...........
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                         Engine
--------------------------------------------------------------------------------------------------------------------------------------------------------
Baseline...........................  2010 MY 11L  2010 MY 11L  2010 MY 11L  2010 MY 15L  2010 MY 15L  2010 MY 15L  2010 MY 15L  2010 MY 15L  2010 MY 15L
                                          Engine       Engine       Engine       Engine       Engine       Engine       Engine       Engine       Engine
--------------------------------------------------------------------------------------------------------------------------------------------------------
--------------------------------------------------------------------------------------------------------------------------------------------------------

                                     Table III-2--Class 7 and 8 Tractor Baseline CO2 Emissions and Fuel Consumption
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                    Class 7                                                    Class 8
                                    --------------------------------------------------------------------------------------------------------------------
                                                    Day cab                                Day cab                              Sleeper cab
                                    --------------------------------------------------------------------------------------------------------------------
                                       Low roof     Mid roof    High roof     Low roof     Mid roof    High roof     Low roof     Mid roof    High roof
--------------------------------------------------------------------------------------------------------------------------------------------------------
CO2 (grams CO2/ton-mile)...........          116          128          138           88           95          103           80           89           94
--------------------------------------------------------------------------------------------------------------------------------------------------------
Fuel Consumption (gal/1,000 ton-            11.4         12.6         13.6          8.7          9.4         10.1          7.8          8.7          9.3
 mile).............................
--------------------------------------------------------------------------------------------------------------------------------------------------------

(ii) Tractor Technology Package Definitions
    The agencies' assessment of the final technology effectiveness was
developed through the use of the GEM in coordination with chassis
testing of three SmartWay certified Class 8 sleeper cabs. The agencies
developed the standards through a three-step process. First, the
agencies developed technology performance characteristics for each
technology, described below. Each technology is associated with an
input parameter which is in turn modeled in the GEM. The performance
levels for the range of Class 7 and 8 tractor aerodynamic packages and
vehicle technologies are described in Table III-3. Second, the agencies
combined the technology performance levels with a projected technology
application rate to determine the GEM inputs used to set the stringency
of the final standards. Third, the agencies input the parameters

into GEM and used the output to determine the final CO2
emissions and fuel consumption levels.
Aerodynamics
    The aerodynamic packages are categorized as Bin I, Bin II, Bin III,
Bin IV, or Bin V based on the aerodynamic performance determined
through testing conducted by the manufacturer. A more complete
description of these aerodynamic packages is included in Chapter 2 of
the RIA. In general, the CdA values for each package and tractor
subcategory were developed through EPA's coastdown testing of tractor-
trailer combinations, the 2010 NAS report, and SAE papers.
Tire Rolling Resistance
    The rolling resistance coefficient for the tires was developed from
SmartWay's tire testing to develop the SmartWay certification, in
addition to testing a selection of tractor tires as part of this
program. The tire performance was evaluated in three levels--the
baseline (average), 15 percent better than the average, and an
additional 15 percent improvement. The first 15 percent improvement
represents the threshold used to develop SmartWay certified tires for
long haul tractors. The second 15 percent threshold represents an
incremental step for improvements beyond today's SmartWay level and
represents the best in class rolling resistance of the tires we tested.
Weight Reduction
    The weight reductions were developed from tire manufacturer
information, the Aluminum Association, the Department of Energy, and
TIAX, as discussed above in Section II.B.3.e.
Idle Reduction
    The benefits for the extended idle reductions were developed from
literature, SmartWay work, and the 2010 NAS report. The agencies
received comments from multiple stakeholders regarding idle reduction
technologies (IRT). Two commenters asked us to revise the default value
associated with the IRT technology, and two commenters want to use IRT
in GEM even without automatic engine shut down (AES). The agencies
proposed AES after 5 minutes with no exceptions to help ensure that the
idle reductions are realized in-use. Use of an AES ensures the main
engine will be shut down, whereas idle reduction technologies alone do
not provide that level of certainty. Without an automatic shutdown of
the main engine, actual savings would depend on operator behavior and
thus be essentially unverifiable. The agencies are finalizing the
calculation as proposed, along with the automotive engine shutdown
requirement. Additional details regarding the comments and calculations
are included in RIA Section <IP_ADDRESS>.