manufacturers would likely add technologies that provide heat from
combustion more readily to the catalyst or improve the catalyst
efficiency at lower temperatures. These technologies could include
calibration changes, thermal management, close-coupled catalysts,
catalyst PGM loading, and possibly secondary air injection. In some
cases, where the catalyst light-off response and efficiency are not
enough to address the cold start emissions, hydrocarbon adsorbers may
be applied to trap hydrocarbons until such time that the catalyst is
lit-off. Note that with the exception of hydrocarbon adsorbers each of
these technologies addresses both NMOG and NOX performance.
Key potential technologies are described in greater detail below.
     Engine Control Calibration Changes--These include changes
to retard spark and/or adjust air/fuel mixtures such that more
combustion heat is created during the cold start on gasoline engines.
Diesel engines may use unique injection timing strategies or other
available engine control parameters. Engine calibration changes can
affect NMOG, NOX and PM emissions.
     Thermal Management--This technology includes all design
attributes meant to conduct the combustion heat into the catalyst with
minimal cooling on both gasoline and diesel engines. This includes
insulating the exhaust piping between the engine and the catalyst,
reducing the wetted area of the exhaust path and/or reducing the
thermal mass of the exhaust system. Close-coupling of catalysts
(packaging the catalysts as close to the head of the engine as possible
to mitigate the cooling effects of longer exhaust piping) can also be
effective, but is more difficult to employ than in light-duty
applications because of durability concerns with highly loaded
operation and the potential increase in fuel consumption to protect the
catalyst from high temperatures.
     Catalyst PGM Loading--Additional Platinum Group Metal
(PGM) loading in the catalyst provides a greater number of sites to
catalyze emissions and addresses NMOG, NOX and PM emissions.
     Selective Catalytic Reduction Optimization--Diesel
applications would need to continue to refine this NOX
emissions control strategy through improved hardware design and
implementation in vehicle applications. Additional engineering
enhancements in the control of the SCR system and related processes
would also help reduce emissions levels.
6. Other HDV Provisions
a. HDV Useful Life
    Currently the HDV regulatory useful life, the period of use or time
during which emissions standards apply, is 120,000 miles or 11 years,
whichever occurs first (40 CFR 86.1805-4). For Tier 3 vehicle criteria
emissions we are proposing to extend the useful life to 150,000 miles
or 15 years, whichever occurs first. This change would better reflect
the improvements in vehicle durability and longevity that have occurred
in the several years since the 120,000 mile useful life was
established, and would maintain consistency with the LEV III MDV
program and with our Tier 3 program for large LDTs, for which the same
useful life period has been proposed. California's LEV III staff paper
included a discussion of the feasibility of this longer useful life
based on experience with it in the PZEV element of the ZEV
mandate.\275\
---------------------------------------------------------------------------

    \275\ ``Preliminary Discussion Paper--Amendments to California's
Low-Emission Vehicle Regulations for Criteria Pollutants--LEV III'',
California Air Resources Board, February 8, 2010.
---------------------------------------------------------------------------

    We are proposing that the new useful life requirement apply to Tier
3 HDVs in all bins except those designated as interim bins, consistent
with the purpose of the interim bins to provide for limited carry-over
of pre-Tier 3 vehicle designs during the phase-in period. Although the
percentage application in each year will therefore depend on each
manufacturer's fleet binning strategy, the declining NMOG+
NOX fleet average standard would ensure a robust phase-in of
the new useful life requirement over the 2018-2022 model years, such
that it is expected to be about 50 percent in 2018, and necessarily
reaches 100 percent by 2022 when the interim bins are no longer
available. For those manufacturers choosing to certify to the voluntary
standards, the new useful life will apply even earlier, in 2016 or
2017. For manufacturers choosing the alternative percent-of-sales NMOG+
NOX alternative, we are proposing that the new useful life
requirement apply to all HDVs counted toward the phase-in requirement,
resulting in a generally equivalent useful life phase-in rate to that
of the primary approach. See Section IV.D.4.b for further discussion of
useful life with regard to GHG standards. We are also proposing that
manufacturers may optionally retain the 120,000 mile/11 year useful
life for PM on interim Tier 3 vehicles that are not phased in to the
Tier 3 p.m. standards.

b. Heavy-Duty Alternative Fuel Vehicles
    As in the proposed light-duty program, we are proposing that
manufacturers demonstrate heavy-duty flex fuel vehicle (FFV) and dual-
fuel vehicle compliance with both the FTP and the SFTP emissions
standards when operating on both the conventional petroleum-derived
fuel and the alternative fuel. Dedicated alternative fuel vehicles
would demonstrate compliance with both the FTP and SFTP emission
standards while operating on the alternative fuel. For all of these
vehicles, this includes the requirement to meet FTP emissions standards
when conducting fuel consumption and GHG emissions testing, and also to
meet the FTP and highway test requirements at high altitudes (see
Sections IV.B.6.e and f). Because FFVs can operate on various
combinations of their conventional and alternative fuel, the emissions
requirements apply to operation at any mix of the fuels achievable in
the fuel tank with commercially available fuels, including for
compliance at high altitudes, even though the required demonstration of
compliance is limited to the conventional and alternative fuels
designated for certification testing.
c. Optional Certification for Vehicles Above 14,000 lbs GVWR
    The HD greenhouse gas (GHG) standards include a provision for
optional certification of complete gasoline-fueled HDVs above 14,000
lbs GVWR to g/mi GHG standards on the chassis test.\276\ Because that
rule does not change the requirements for certification to criteria
pollutant standards, manufacturers choosing this option would have to
certify the vehicle for GHGs, but use installed engines certified to g/
hp-hr standards for all other emissions. We believe it may provide
benefits for both the environment and the manufacturers to allow
consistent certification of these vehicles on a chassis test for all
emissions, treating any vehicles so certified in the same way as Class
3 vehicles, including applicable standards, inclusion into fleet
average calculations, test fuel, useful life, and the application of
Tier 3 evaporative emissions requirements.
---------------------------------------------------------------------------

    \276\ 76 FR 57106 (September 15, 2011).
---------------------------------------------------------------------------

    We request comment on the value of, and any issues concerning, our
providing such an option to manufacturers of both gasoline and diesel-
fueled HDVs above 14,000 lbs GVWR, including the applicability of the
existing chassis test cycles for these larger trucks. Comment is also
requested on whether manufacturers of such vehicles that are certified
to a Final Tier 3 bin should be allowed to exclude them from the fleet
average NMOG+NOX calculation, as a means of encouraging the
production of such low-emissions vehicles by not penalizing them for
having emissions somewhat above the Class 3 fleet average. Finally, we
also request comment on whether any such option for diesel-fueled HDVs
should extend to GHG emissions as well.
d. Existing Provision To Waive HDV PM Testing
    EPA's existing program includes a provision for manufacturers to
waive measurement of PM emissions in non-diesel heavy-duty vehicle
emissions testing. We are proposing to eliminate this provision. We
believe that the PM standards we are proposing for these vehicles are
of sufficient stringency that routine waiver of testing would not be
appropriate. The California Air Resources Board LEV III program
reflects this view. We do not expect this change to be onerous for
manufacturers, as the number of heavy-duty vehicle families is not
large. Even so, we request comment on alternative approaches, such as
that being proposed for light-duty vehicles, involving measuring PM on
a subset of families each year. We request comment on any other
potential situations in which waiver of PM measurement may be
appropriate. Note that we are proposing to waive the PM emissions
measurement requirement for small manufacturers, for reasons explained
in Section IV.E.
e. Meeting HDV Standards in Fuel Consumption and GHG Emissions Testing
    As with the proposed light-duty Tier 3 program, we are proposing
that HDVs must meet the FTP bin standards when tested over both the
city and highway test cycles. We do not believe this adds a very
significant test burden as vehicle emissions are already required to be
measured when these tests are run for GHG and fuel consumption
determinations. Nor do we believe that this proposed requirement is
design forcing. Rather, we are proposing this requirement to ensure
that test vehicle calibrations are not set by manufacturers to minimize
fuel consumption and GHG emissions, at the expense of high criteria
pollutant emissions. Considering the additional work involved in
measuring PM emissions and the reduced likelihood of high PM emissions
on the highway test, we are not proposing that PM emissions testing be
included in this requirement, but we ask for comment on whether we
should instead include them, but waive the requirement to measure them
in manufacturers' certification testing, to ensure that any unforeseen
PM control technology challenges in highway driving conditions are
addressed in the future.
f. HDV Altitude Requirements
    As in the past, we intend that HDV Tier 3 standards result in
emissions controls that are effective over a full range of operating
altitudes. We do not anticipate that the proposed FTP bin standards
would require the use of special hardware to achieve compliance at
altitude. We also do not believe that adjustment to the FTP standards
is appropriate for HDV testing at altitude, as we expect that
manufacturers would be able to meet these standards with adequate
compliance margin to cover this test condition. As in the proposed
light-duty program, and for the same reasons, we are not proposing to
require that HDVs comply with SFTP standards at altitude.

C. Evaporative Emissions Standards and Onboard Diagnostic System
Requirements

    Gasoline vapor emissions from vehicle fuel systems, which are a
mixture of hydrocarbon compounds, occur when a vehicle is in operation,
when it is parked, and when it is being refueled. These evaporative
emissions from gasoline-powered vehicles which occur on a daily basis
are primarily functions of temperature, fuel vapor pressure, and
activity. EPA first instituted evaporative emissions standards in the
early 1970s to address hydrocarbon emissions when vehicles are parked
after being driven. These are commonly referred to as hot soak and
diurnal emissions. Over the subsequent years the test procedures have
been modified and improved, the standards have been revised to be more
stringent, and we have addressed emissions which arose from new fuel
system designs by establishing new requirements such as running loss
emission standards and test procedure provisions to address resting
losses (e.g., permeation). Onboard refueling vapor recovery (ORVR)
requirements for control of refueling emissions first began to phase-in
for light-duty vehicles (LDVs) and light-duty trucks (LDTs) in the 1998
MY. These were later expanded to cover medium-duty passenger vehicles
(MDPVs) and some heavy-duty gasoline vehicles (HDGVs). Even though
evaporative and refueling emission control systems have been in place
for

most of these vehicles for many years, evaporative emissions still
contribute 30-40 percent of the on-road mobile source hydrocarbon
inventory. These fuel vapor emissions are ozone and PM precursors, and
also contain air toxics such as benzene. Even though there are mature
evaporative emission control programs in place, further hydrocarbon
emission reductions are needed and can be achieved from highway motor
vehicles. Vehicles demonstrating near zero fuel vapor emissions have
been certified by CARB and a limited number are in-use in California
and other states. Furthermore, test programs conducted by the
Coordinating Research Council and EPA show that attention is needed to
insure better in-use performance of current evaporative control
systems. Cost effective hydrocarbon emission reductions can be achieved
through new vehicle standards and improved focus on in-use performance.
    This section discusses the proposed vehicle-related evaporative
emission standards and related provisions for LDVs, LDTs, MDPVs, and
HDGVs. As discussed below, we are proposing more stringent standards
that would apply for the 2- and 3-day evaporative emissions tests, a
new canister bleed test and emission standard, a new certification test
fuel specification,\277\ and a new fuel/evaporative system leak test
procedure and emission standard. We are also proposing refueling
emission controls for a portion of HDGVs over 10,000 lbs gross vehicle
weight rating (GVWR). This section also describes proposed phase-in
flexibilities, credit and allowance programs, and seeks comment on
several other issues related to evaporative emissions control.
---------------------------------------------------------------------------

    \277\ For flexible fuel vehicles (FFVs) certification fuel for
evaporative and refueling emissions testing would remain a 9 RVP
gasoline splash blended with ethanol to yield a blend containing 15
percent ethanol.
---------------------------------------------------------------------------

    The proposed evaporative emissions program has six basic elements:
(1) The Tier 3 evaporative emission phase-in program (MY 2018-2022+),
(2) the early allowance/credit program (MY 2015-2016), (3) the
transitional program (MY 2017), (4) requirements for HDGVs including
ORVR, (5) a leak emission standard and test procedures, and (6) other
miscellaneous proposed changes and areas for comment.
    In this proposed rule, the vehicle classifications, LDVs, LDTs,
MDPVs, and HDGVs, would remain unchanged from Tier 2. For purposes of
this discussion of the proposed Tier 3 evaporative emissions program,
the vehicle standards can be further placed in four categories: (1)
``Zero evaporative emission'' PZEV vehicles certified by CARB as part
of the ZEV program, (2) vehicles certified by CARB to meet LEV III
evaporative emission program requirements on CARB certification fuel (7
RVP E10), (3) vehicles meeting the proposed Tier 3 evaporative
emissions program requirements using the proposed certification test
fuel (9 RVP E15), and (4) transitional vehicles meeting current EPA
evaporative requirements on Tier 2 certification fuel (9 RVP
E0).278 279 For ease of reference these four categories may
be referred to as PZEV evap, LEV III evap, Tier 3 evap, and Tier 2 evap
in this section.\280\

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

    \278\ We adopted the most recent vehicle evaporative emission
standards for LDVs, LDTs, and MDPVs in 2007 (72 FR 8428, February
26, 2007). The most recent standards for HDGVs were adopted in 2000
(66 FR 5165, January 18, 2001).
    \279\ See Section IV.D.1 for a discussion of the proposed
certification fuel changes, including discussion of options for and
implications of the certification test fuel having 10 percent
ethanol.
    \280\ ``PZEV evap'' as discussed here refers only to the
evaporative emission and useful life requirements of the PZEV
program, not the exhaust emission requirements.
---------------------------------------------------------------------------

1. Tier 3 Evaporative Emission Standards
a. Proposed Standards
    This proposal for evaporative emissions builds on previous EPA
requirements as well as CARB's recent LEV III rule which starts phasing
in with the 2018 MY. This proposal facilitates a national program for
vehicle evaporative emissions control. We believe the proposed program
is appropriate since it would require new evaporative emissions control
technology in new vehicles while also achieving improved in-use system
performance.
    This section describes proposed requirements for LDVs, LDTs, MDPVs,
and HDGVs. The proposal includes more stringent emission standards for
hot soak plus diurnal emissions (2- and 3-day tests), plus a new
canister bleed standard and testing requirement for measuring emissions
from the fuel tank and the evaporative canister. The proposal also
introduces a limited corporate averaging program for demonstrating
compliance with the hot soak plus diurnal standards. We are proposing a
phase-in of the Tier 3 evaporative emission standards that would begin
with the 2017 MY, with incentives for manufacturers to introduce Tier 3
compliant vehicles earlier or in greater numbers than required. The
proposal includes revised provisions for demonstrating compliance with
the evaporative emission standards at high altitude. See Section IV.C.3
for additional provisions for the HDGV category.
i. Hot Soak Plus Diurnal Standards
    Previous hot soak and diurnal emission controls have dramatically
reduced vehicle evaporative emissions over the past thirty plus years.
However, some emissions remain and control technology is available to
capture these emissions in a cost effective manner. Toward that end,
EPA is proposing more stringent hot soak plus diurnal evaporative
emission standards for the Tier 3 program. The standards apply to both
the 2-day and 3-day evaporative emission test requirements.
    The standards are designed to bring into the broader motor vehicle
fleet the ``zero evap'' technology used by the manufacturers in their
partial zero emission vehicles (PZEVs). Manufacturers developed this
``zero evap'' technology as part of their response to meeting the
requirements of the CARB Zero Emission Vehicle (ZEV) program. This
program, which is in effect in 11 other states, allows manufacturers to
meet their ZEV mandate percentages (totally or in-part) by the use of
vehicles which among other characteristics have very low fuel vapor
emissions.
    The standard levels presented in Table IV-18 are designed primarily
to accommodate what is often referred to as new vehicle background
hydrocarbon emissions. These emissions arise from the off-gassing of
volatile hydrocarbons from plastics, rubbers, and other polymers found
in new vehicles (e.g., new tires, interiors, seats, fuel system
components, paints, and adhesives). In the field these emissions
decrease over time as the vehicle ages, but this cannot necessarily be
replicated in the time that manufacturers normally allocate for vehicle
certification. In the past manufacturers have employed techniques such
as vehicle baking (discussed below) to accelerate the rate of this off-
gassing, and until recently it has not been a major consideration for
certification.
    In the past EPA has set relatively uniform (but not identical)
evaporative emission standards for LDVs and LDTs and somewhat higher
values for HDGVs. The proposed hot soak plus diurnal emission standards
presented in Table IV-18 are somewhat higher as vehicles get larger in
weight and physical size. This is because in general the vehicles have
higher levels of non-fuel background emissions as they get larger. As
mentioned above, the standards, which are approximately a 50 percent
reduction from the existing hot soak plus diurnal standards, are
intended

primarily to accommodate non-fuel background emissions. Thus, the
technology focus for the proposed Tier 3 evaporative emission standards
is for vehicles to have essentially zero fuel vapor emissions.
    As described in more detail in Section IV.C.2 below, EPA is
proposing a program that would allow manufacturers to demonstrate
compliance with the proposed hot soak plus diurnal evaporative emission
standards using averaging concepts. Under the proposal, manufacturers
may comply by averaging within each of the four vehicle categories but
for the reasons discussed below, may not rely on averaging across
categories. The technical approaches to meeting the proposed standards
are discussed in Section IV.C.2. EPA is not proposing any changes to
the existing light-duty running loss or refueling emission standards
with the Tier 3 proposal, with the exception of the certification test
fuel requirement.

  Table IV-18--Proposed Evaporative Emission Standards (g/test) \a\ \b\
                                   \c\
------------------------------------------------------------------------
                                                    Highest hot soak +
                                                   diurnal level (over
                Vehicle category                   both 2-day and 3-day
                                                      diurnal tests)
------------------------------------------------------------------------
LDV, LDT1......................................                    0.300
LDT2...........................................                    0.400
LDT3, LDT4, MDPV...............................                    0.500
HDGVs..........................................                    0.600
------------------------------------------------------------------------
\a\ The standards are in grams of hydrocarbons as measured by flame
  ionization detector during the diurnal and hot soak emission tests in
  the enclosure known as the sealed housing for evaporative
  determination (SHED).
\b\ Note that the proposed standards are the same for both tests;
  current standards are slightly different for the 2- and 3-day tests.
\c\ Vehicle categories are the same as in EPA's Tier 2 final rule; see
  65 FR 6698, February 10, 2000.

ii. Canister Bleed Emission Standard
    In addition to more stringent hot soak plus diurnal standards, EPA
is proposing a new canister bleed emission test and standard as part of
the Tier 3 program. The proposed bleed test procedure is described in
Section IV.C.4.a., below. The purpose of the new test and standard is
to ensure that near-zero fuel vapor emissions are being emitted by
vehicles from the fuel tank through the evaporative emission canister.
Under this proposal, manufacturers would be required to measure diurnal
emissions over the 2-day diurnal test procedure from just the fuel tank
and the evaporative emission canister and comply with a 0.020 g/test
standard for all LDVs, LDTs, and MDPVs and 0.030 g/test for HDGVs. The
feasibility of this standard is discussed in Section IV.C.2.g.ii below.
EPA is proposing not to apply the averaging program to this new bleed
test standard as compliance is relatively straightforward and low in
cost. Therefore, each evaporative/refueling emission family certified
by manufacturers would need to demonstrate compliance with their
respective standard. As discussed below, the canister bleed standard
would not apply at high altitude. The canister bleed test and standard
drives canister design elements such as total gasoline working
capacity, internal architecture, and the type of carbon used. Since the
performance of the canister is also evaluated in the hot soak plus
diurnal evaporative emissions sealed housing for evaporative
determination (SHED) test we are proposing that the canister bleed
emission standard not be included in the In-Use Verification Program
but it must be met in use. We would not expect to have canister bleed
specific family criteria for certification but the test would have to
be completed and the standard met for each evaporative/refueling family
including potentially twice if there were two canisters used. A
deterioration factor would not be required, but as mentioned above, the
standard would have to be met in-use and could be evaluated in EPA
confirmatory testing.
iii. Early and Transitional Hot Soak Plus Diurnal Standard
    As part of its LEV III program, CARB has included an alternative
set of evaporative emission standards, referred to as Option 1
standards. These are shown in Table IV-19.

                            Table IV-19--CARB Option 1 Evaporative Emission Standards
----------------------------------------------------------------------------------------------------------------
                                                             Highest hot soak + diurnal level
                                                              (over both 2- and 3-day diurnal
                     Vehicle category                                 tests) (g/test)           Running Loss (g/
                                                           ------------------------------------       mile)
                                                              Vehicle SHED        Rig SHED
----------------------------------------------------------------------------------------------------------------
Passenger Car.............................................             0.350               0.0              0.05
LDT <= 6,000 lbs GVWR.....................................             0.500               0.0              0.05
All other vehicles > 6,000 lbs GVWR.......................             0.750               0.0              0.05
----------------------------------------------------------------------------------------------------------------

     The Option 1 standards include evaporative emission standards (hot
soak plus diurnal) that are slightly higher numerically than our
proposed standards. Vehicles certified under this option may not use
averaging in the CARB LEV III program because they basically represent
the same evaporative emission standards as exist for PZEVs under CARBs
ZEV program wherein averaging is not permitted. Option 1 also includes
an additional test of the vehicle fuel system (rig test) that from an
engineering perspective is practically more difficult to conduct than
the bleed test discussed above and is intended to force manufacturers
to demonstrate at certification that their stand alone (not in chassis)
fuel/vapor control system designs have no (<=54 mg) fuel vapor
emissions. EPA is not proposing that Option 1 be part of the long term
Tier 3 evaporative emission program. While we see the merit of the rig
test as an engineering design and development tool for the
manufacturers, by its very nature, the rig SHED standard is not
implementable as an enforceable standard. We believe that the hot soak
plus diurnal SHED test and the canister bleed test will accomplish the
same objective of keeping fuel vapor emissions to a minimum.
    EPA believes most manufacturers will prefer to certify to the
averaging based standards proposed by EPA (similar in

stringency and program construct to CARB Option 2). However, because
some manufacturers may have vehicle models meeting the CARB Option 1
standards and emission requirements now or in the near future, EPA is
proposing that compliance with the CARB Option 1 standards would be an
acceptable interim alternative to compliance with the proposed Tier 3
evaporative emission standards if the model is certified by CARB before
the 2017 MY. EPA proposes that these vehicles could then be certified
using carryover provisions through the 2019 MY.\281\ As noted in the
following sections, vehicles certified under this provision would count
toward the phase-in percentage requirements and could earn allowances
as discussed below, but the vehicles would not be eligible to earn or
use credits for the evaporative emissions averaging program. Carryover
vehicles would have to meet EPA leak emission standard to be counted
toward the sales percentage requirements for 2018 and later model
years.
---------------------------------------------------------------------------

    \281\ EPA is proposing to incorporate by reference the CARB
Option 1 test procedures and emission standards for this interim
period.
---------------------------------------------------------------------------

b. Useful Life
    Trends indicate that vehicle lifetimes are increasing. It is
important that emission control systems be designed to meet
requirements while vehicles are in use. As discussed in Section IV.A
and IV.B of this proposal, along with the new emission standards, we
are proposing a longer useful life of 150,000 miles/15 years, whichever
comes first, for LDTs up to 6,000 lbs GVWR but over 3,750 lbs loaded
vehicle weight (LVW) (LDT2s), all LDTs over 6,000 lbs GVWR (LDT3/4),
MDPVs, and HDGVs between 8,501 and 14,000 lbs GVWR. The proposed longer
useful life would also apply to certifications to the Tier 3
evaporative emission requirements. For an evaporative/refueling family
certified to 150,000 miles/15 year useful life for evaporative
emissions this useful life would also apply to the refueling, leak, and
high altitude standards, where applicable when a family certifies to
the Tier 3 evaporative emission requirements. All of these standards
impact the fuel and vapor control systems and it is technologically
consistent to require the same useful life for these standards because
they all rely on the mechanical integrity, durability, and operational
performance of the same components in the evaporative emissions control
system.
    Due to limitations in the CAA, for LDVs and for LDTs up to 6,000
lbs GVWR and at or below 3,750 lbs LVW (LDT1s), we are keeping the
current useful life of 120,000 miles/10 years unless, as described in
Section IV.A, a manufacturer elects alternative exhaust emission
requirements that are associated with 150,000 mile/15 year useful life
for these vehicles. For manufacturers that select those optional
standards, the useful life of 150,000 miles/15 years would apply for
all Tier3 evaporative emission standards including the hot soak plus
diurnal emission standards, the refueling emission standard, and the
leak standard because of the design and operating relationships between
the engine, the fuel system, the evaporative control system and their
various components.
    During the early and transitional program periods and until the
final year of the allowed phase-in period for the Tier 3 evaporative
emission program (MY 2015-2022) the differences between the proposed
exhaust and evaporative emission phase-in programs presents the
possibility that in some cases a manufacturer could certify a model to
the Tier 3 exhaust requirements but not necessarily to the Tier 3
evaporative emission requirements.\282\ In those situations, we are
proposing that a family could have a 150,000 miles/15 years useful life
for exhaust emissions but maintain the current useful life for all of
the evaporative and refueling emission standards. We also propose that
during the phase-in period, if a family is certified to the Tier 3
evaporative emission requirements but not yet certified for Tier 3
exhaust emission requirements, then the useful life could be 150,000
miles/15 years for evaporative and refueling emissions standards but
the current useful life for exhaust emissions, However, by the 2022 MY
EPA proposes that the useful life for all of these requirements would
be 150,000 miles/15 years for LDT2/3/4s, MDPVs, and HDGVs since by that
model year all vehicles must be certified using Tier 3 certification
fuel and test procedures and meet Tier 3 evaporative emission
standards.\283\
---------------------------------------------------------------------------

    \282\ By the 2020 MY, all Tier 3 evaporative system emissions
certifications must use Tier 3 certification test fuel and test
procedures. This affects evaporative (hot soak plus diurnal),
canister bleed, refueling, and leak emission standards
certification.
    \283\ The only exception here would be for vehicles not meeting
Tier 3 evaporative emission requirements in the 2022 MY as a result
of the use of previously earned allowances and small businesses
which have until the 2022 MY to meet the proposed Tier 3 evaporative
emission requirements.
---------------------------------------------------------------------------

    OBD regulations call for the systems to operate effectively over
the useful life of the vehicle. We are not proposing to change that
requirement, but rather to clarify that during the early and transition
years of the phase-in (MY 2015-2022), all of the OBD monitoring
requirements have the same useful life as that for the exhaust emission
standard except for the evaporative system leak monitoring requirement
which has the same as that required for the evaporative and refueling
emission standards control systems.
2. Evaporative Emissions Program Structure and Implementation
Flexibilities
a. Percentage Phase-In Requirements
    The proposed Tier 3 evaporative emission standards would be phased
in over a period of six model years (MYs), including a transitional
year in 2017. For MY 2017, except as discussed below, the requirement
would apply to 40 percent of a manufacturer's combined sales of LDVs,
LDT1s, and LDT2s. To be consistent with the start date for new exhaust
standards affecting these vehicles, the phase-in requirements would not
include vehicles over 6,000 lbs GVWR until the 2018 MY. For the 2018-
2019 MYs, the requirement would apply to 60 percent of a manufacturer's
sales of all LDVs, LDTs, MDPVs, and HDGVs. This would increase to 80
percent for MYs 2020 and 2021 and by MY 2022 it would apply to 100
percent of sales in these four categories. Beginning in MY 2018 any
vehicle included in the percentage projection, except vehicles that had
earned allowances would have to meet the leak emission standard.
    Our proposal for MY 2017 has two options and we are seeking comment
on a third option. The first, which we are calling the ``percentage''
option, would require that 40 percent of a manufacturer' s LDVs, LDT1s,
and LDT2s sold outside of California and the states that have adopted
the CARB ZEV or LEV III programs must meet the Tier 3 evaporative
emission requirements on average. The second which we are calling the
``PZEV zero evap only'' option, would require a manufacturer to sell
all of the LDVs, LDT1s, and LDT2s certified with CARB as meeting the
PZEV evaporative emission requirements (zero evap) in MY 2017
throughout all of the U.S. and not to offer for sale any non-PZEV zero
evap version of those vehicles in any state whose vehicles are covered
by the Tier 3 evaporative emission standards. Thus, this would apply to
sales in any state except for California and states that

have adopted the CARB ZEV or LEV III programs under section 177 of the
Clean Air Act. Under this second option, no tracking of sales or end of
year compliance calculation would be required. Some manufacturers may
find this option attractive, as they have more limited product
offerings and find tracking of production and sales more difficult.
    The basic goal of the 2017 MY program is to provide evaporative
emission reductions benefits in the other states which are similar to
those expected in California and the states which adopted LEV III under
section 177 of the Clean Air Act. Due to model phase-out and phase-in
issues related to current and future products, some manufacturers have
indicated that increasing production of Tier 3 evaporative emission
compliant vehicles for the 2017 MY to meet the 40 percent value
discussed above could be difficult and costly. To address this issue,
we are asking for comment on a third option: decreasing this value from
40 percent to 20 percent but requiring that these same vehicles also
meet the leak emission standard in the 2017 MY. This approach has the
potential to address the transition issue and EPA believes that the
leak standard will provide evaporative emission reduction benefits
equal to or greater than the Tier 3 evaporative emission standards.
Thus, under this approach, the manufacturers' product transition
concerns could be addressed and the overall evaporative emission
reductions would still be achieved for 2017 MY vehicles. As discussed
below, beginning in the 2018 MY, a Tier 3 compliant vehicle must also
meet the leak emission standard. This option would be effective only in
the 2017 MY. EPA asks for comment on whether this option should require
the leak emission standard to apply to the same 20 percent of vehicles
that are complying with the Tier 3 evaporative emission requirements,
or whether this option should allow manufacturers the flexibility to
meet some or all of the 20 percent leak emission standard requirement
with vehicles not yet compliant with the Tier 3 evaporative
requirements.
    At the time of certification, manufacturers would identify which
families would be included in their Tier 3 evaporative emission
percentage calculations (this could be families above or below the
individual Tier 3 evaporative emission standards for the given class of
vehicles as well as vehicles meeting CARB's Option 1 standards) and
could also include earned allowances as discussed below. They would use
projected sales information for these families plus allowances as
desired and available, to show how they expect to meet the phase-in
percentages for the model year of interest. At the end of the model
year they would be expected to show that the percentages were met and
if not they would either use additional allowances or bring more
vehicle families into the calculation.
    Requiring a showing at the time of certification based on projected
sales requires due diligence by the manufacturers and EPA, but the Tier
3 evaporative emissions program allows for fleet averaging, so a
validation or ``truing up'' of these sales projections is necessary for
determining compliance with the requirements of the standard. This is
discussed in Sections IV.C.2.c.and d. As discussed further below,
validated sales information would also be used for earning early
allowances and to show compliance with the alternative phase-in
schedule approach.
    For these purposes, vehicles included in the phase-in percentage
could be: (1) Families which certified to CARB LEV III requirements in
MYs 2015 and 2016 (CARB Option 1), (2) families certified to meet Tier
3 evaporative emission requirements, and (3) vehicles from the early
allowance program. However, beginning in the 2017 MY, any new
evaporative/refueling emission family certifications would have to meet
the proposed EPA Tier 3 certification requirements for both test
procedure and certification test fuel for the evaporative and refueling
emission standards. The leak emission standard would apply in the 2018
MY. Furthermore, assuming other regulatory provisions related to
carryover of emissions data are met, 2015-2016 MY CARB evaporative
emissions certifications could be carried over until the end of the
2019 MY and included as compliant vehicles within the program if they
met the leak emission standard.
    The phase-in percentages for MYs 2017 through 2022 reflect a
percentage phase-in concept applied successfully by EPA in previous
rules involving evaporative and refueling emissions control. The
proposed phase-in provides an appropriate balance between the needed
emission reductions and time for the manufacturers to make an orderly
transition to the new technology on such a broad scale. The higher
initial percentage here is appropriate because the expected evaporative
emission control technology is already being used to varying degrees by
16 manufacturers on over 50 vehicle models today and is projected to
gain even deeper penetration by 2017 due to the partial zero emission
vehicles (PZEV) option within the CARB ZEV program.
    As a flexibility, we are proposing to allow manufacturers to
demonstrate compliance with the phase-in percentage requirements of the
evaporative emissions program by using a manufacturer-determined
alternative phase-in percentage scheme. Under this approach, before the
2018 MY, manufacturers would have to present a plan to EPA which
demonstrates that the sum of the product of a weighting factor and the
percentages of their U.S. vehicle sales for each model year from 2018
through 2022 is greater than or equal to 1040. The 1040 value is equal
to the sum of the product of the weighting factors and the percentage
requirements for MYs 2018 through 2022, calculated in the following
manner: [(5)(2018MY %)+4(2019MY %)+3(2020MY %)+2(2021MY %)+(1)(2022MY
%)]. This would allow manufacturers to use a phase-in more consistent
with product plans which may call for a lower percentage in the early
years or to benefit from producing and selling more than the minimum
percentage of compliant vehicles early. This flexibility could also be
helpful in the event that a manufacturer elects to put some vehicles on
a different phase-in schedule for meeting Tier 3 exhaust and
evaporative emission standards. As explained further below, any
allowances earned could be counted toward compliance with the 1040
value. Within this proposed flexibility EPA asks for comment in three
areas. First, we seek comment on the need for and value of this
alternative phase-in percentage flexibility option. Second, we did not
include the 2017 MY in this flexibility because we believe that the
PZEV zero evap nationwide option, the use of any earned allowances, and
the ability to have a deficit in a given year are sufficient. However,
we ask for comment on including the 2017 MY ``percentage'' option in
this flexibility (both the 40 and 20 percent approaches discussed
above). If after comment the 40 percent option from the 2017 MY is
included in the final rule, the sum of the percentages would include an
additional 240= (6)(40) for a total; of 1280; the equation above would
add a term of (6)(2017MY %). Similarly, we ask for comment on whether
the 20 percent option from the 2017 MY should be included in the
alternative phase-in approach. If it is included in the final rule, the
sum of the percentages would include an additional 120= (6)(20) for a
total; of 1160; the equation above would add a term of (6)(2017MY %).

b. Early Allowance Program
    We are proposing incentives for early introduction of vehicles
compliant with the Tier 3 evaporative emission regulations.
Manufacturers could take advantage of these incentives prior to MY 2018
by selling vehicles that meet the Tier 3 evaporative emission
regulations earlier than required or in greater numbers than required.
    As described below, manufacturers could earn ``allowances'' for
selling any vehicle certified to the proposed Tier 3 evaporative
emission regulations earlier than required. The vehicles could be LDVs,
LDTs, MDPVs, or HDGVs. Specifically these include the following: (1)
For MYs 2015 and 2016, any LDVs and LDTs meeting the Tier 3 evaporative
emission regulations and sold outside of California and the states that
have adopted CARB's ZEV or LEV III programs, (2) for MYs 2015-2017, any
MDPV or HDGV meeting the Tier 3 evaporative emission regulations early
and sold in any state, (3) for MY 2017, any LDT3/4 meeting the Tier 3
evaporative emission regulations and sold outside of California and the
states that have adopted CARB's LEV III or ZEV programs, and (4) for
MYs 2015-2017, any HDGV between 10,001 and 14,000 lbs GVWR meeting the
refueling emissions regulations and sold outside of California and the
states that have adopted CARB's LEV III or ZEV programs.
    In order to demonstrate compliance with the proposed Tier 3
evaporative emission regulations, the vehicles could be certified to
either the proposed Tier 3 evaporative emission standards or CARB's
PZEV zero evaporative emission and useful life requirements. Vehicles
generating allowances would have to meet the proposed evaporative
emission standards (CARB Option 1 or EPA Tier 3), the high altitude
evaporative emission standard, the canister bleed standard as well as
the refueling emission standards. Manufacturers would earn one
allowance for each qualifying vehicle sold. Manufacturers can use these
allowances in MY 2017 through 2022 to help demonstrate compliance with
the phase-in percentage requirements and fleet average evaporative
emission standards for those years.
    Allowances would be used in the compliance determination in the
following manner. Vehicles qualifying for allowances could be used in
the fleet average evaporative emission standard calculation for any
year during the phase-in. This would apply to the primary phase-in and
alternative phase-in programs. Allowance vehicles would be entered into
the compliance calculation with an emission value equivalent to the
evaporative emission standard for their vehicle category from Table IV-
18 even if it was certified to CARB Option 1 standards (Table IV-19).
For the percent phase-in requirement in either the primary or
alternative phase-in schemes, allowance vehicles would count for one
vehicle for each allowance used within their vehicle category. For the
primary scheme this would be counted as one vehicle, but for the
alternative phase-in option the value would be multiplied by the
weighting factor (5 for 2018, 4 for 2019, 3 for 2020, etc). Within the
alternative phase-in scheme the manufacturer would be limited to using
these early allowances for no more than 10 percentage points of the
phase-in requirements in any given model year (e.g., MYs 2018-2022).
EPA believes this limitation is appropriate. Early introduction of
``zero evap'' technology should be encouraged, but not necessarily at
the expense of its widespread use across the various vehicle categories
as the phase-in progresses. The proposed allowances are designed
primarily to facilitate manufacturer transition during the program
phase-in. As such, we propose that they could not be traded between
manufacturers and unused allowances would expire after the 2022 MY.
    An example here may be helpful in demonstrating how the proposed
concept would work. Take a hypothetical manufacturer who earned 10,000
allowances in 2015 and 2016 and sells 100,000 units per year. In 2018,
the manufacturer would have a phase-in requirement of 60 percent or
60,000 vehicles. For the primary phase-in option the manufacturer could
use part or all of its allowances in 2018. For the alternative phase-in
scheme the proposed regulations would limit the use of allowances to 10
percentage points at the 60 percent. Without a multiplier this would
require the use of all 10,000 allowances in 2018, but with the proposed
multiplier only 2,000 allowances would be needed to reach the 10
percentage point maximum. Using a similar calculus, the manufacturer
could use another 10 percentage points in 2019, but it would require
2,500 allowances since the multiplier is 4. The number of allowances to
reach 10 percentage points would increase each year as the multiplier
decreased.
    For the MY 2017, manufacturers choosing EPA's proposed
``percentage'' option (see Section IV.C.2.a) could earn allowances for
sales of LDT3s, LDT4s, MDPVs, and HDGVs that meet the proposed Tier 3
evaporative emission standards and other related requirements assuming
their LDV, LDT1/2 sales meet the 40 percent requirement. Similarly,
manufacturers choosing EPA's proposed ``PZEV zero evap only'' option
could earn allowances in MY 2017 for LDT3/4s, MDPVs, and HDGVs that
meet the CARB Option 1 evaporative emission standards and related
requirements. For both the ``percentage'' and ``PZEV zero evap only''
options for the 2017 model year, to avoid double counting, the
allowances would be earned only for those vehicles sold outside of
California and the states that have adopted CARB's LEV III/ZEV program
requirements. Vehicles earning allowances could either be vehicles
certified to the Tier 3 evaporative emission standards or vehicles
certified using carryover data from the CARB PZEV zero evaporative
emission requirements from the 2015 or 2016 MYs. Since credits and
allowances serve primarily the same purpose and allowing for splits of
allowances/credits greatly complicates program implementation, we are
proposing that manufacturers could only earn allowances in MYs 2015-
2017 for any qualifying LDT3s, LDT4s, MDPVs, and HDGVs since these
vehicles are not covered by the proposed Tier 3 standards until the
2018 MY. EPA asks for comment on whether this opportunity to earn
allowances coupled with the aforementioned restriction on their use is
the appropriate balance.
c. Evaporative Emissions ABT
    Throughout EPA's programs for mobile source emission controls, we
have often included emission averaging programs for exhaust emissions.
An emission averaging program is an important factor we take into
consideration in setting emission standards under the Clean Air Act. An
emission averaging program can reduce the cost and improve the
technological feasibility of achieving standards, helping to ensure the
standards achieve the greatest achievable reductions, considering cost
and other relevant factors, in a time frame that is earlier than might
otherwise be possible. Manufacturers gain flexibility in product
planning and the opportunity for a more cost-effective introduction of
product lines meeting a new standard. Emission averaging programs also
create an incentive for the early introduction of new technology, which
allows certain emission families to act as leaders for new technology.
This can help provide valuable information to manufacturers on the
technology before they apply the technology throughout their product
line.

    These programs generally involve averaging and banking, and
sometimes trading (ABT). Averaging allows a manufacturer to certify one
or more families at emission levels above the applicable emission
standards as long as the increased emissions are offset by one or more
families certified below the applicable standards. These are referred
to as family emission limits (FELs). The over-complying families
generate credits that are used by the under-complying families.
Compliance is determined on a total mass emissions basis to account for
differences in production volume, and on other factors as necessary.
The average of all emissions for a particular manufacturer's production
within category must be at or below the level of the applicable
emission standards. Banking allows a manufacturer to generate emission
credits and bank them for future use in its own averaging program in
later years. Trading allows a manufacturer to sell credits or obtain
credits from another manufacturer.
    EPA is proposing an emissions ABT program for the Tier 3 hot soak
plus diurnal evaporative emissions standards. This would be the EPA's
first averaging program for evaporative emissions from light-duty or
heavy-duty vehicles. It would not apply to the high altitude standard,
the canister bleed standard or the leak emission standard because it is
the low altitude ``zero evap'' hot soak plus diurnal standard which
will drive the fundamental technology used to comply with all of these
requirements. EPA is proposing to include trading of emission credits
between manufacturers, but in past similar programs there have been
very few trades. Incorporating trading within the program adds a
significant degree of complexity, so we are seeking comment on the need
for and value of including trading.
    The evaporative emissions ABT program would start with the 2017 MY
for the percentage option. The programs would continue for the 2018 MY
and beyond and would not sunset, as does the allowance program.
Vehicles generating averaging/banking credits in the 2017 MY or later
would not be permitted to also generate allowances as this would be
double counting.
    A key element of an averaging program is the identification of the
averaging sets. This sets the criteria for which emission families can
be averaged for purposes of compliance as well as credit and deficit
determinations. We are proposing four averaging sets and the applicable
emission standard for each of the averaging sets as shown in Table IV-
18. Except as noted in section d below, credit exchanges between
averaging sets would not be permitted. Participation in averaging is
voluntary since a manufacturer could elect to certify each family
within the averaging set to its individual limit as if there was no
averaging program.
    An evaporative emission ABT includes two very distinct steps. The
first is the determination of the credit/deficit status of each family
relative to its applicable standard from Table IV-18. The second is the
role of ABT in the overall compliance demonstration which will be
discussed in Section IV.C.2.d which follows.
    A manufacturer choosing to participate in the evaporative emissions
ABT program would certify each emission family to an FEL. The FEL
selected by the manufacturer becomes the emission standard for that
emission family. As noted below, emission credits (or deficits) are
based on the difference between the emission standard that applies (by
vehicle category) and the FEL. The vehicles would have to meet the FEL
for all emission testing.
    We are proposing that the FELs selected by the manufacturer would
have to be selected at 0.025 g/test increments above or below the
applicable Tier 3 evaporative emission standards for each vehicle
category. FELs could not be set any higher than 0.500 g/test for LDVs,
0.650 g/test for LDT1s and LDT2s, 0.900 g/test for LDT3s and LDT4s,
1.000 g/test for MDPVs, 1.4 g/test for HDGVs at or below 14,000 lbs
GVWR, and 1.9 g/test for those above 14,000 lbs GVWR, respectively.
These FEL caps are the 3-day hot soak plus diurnal emission standards
currently applicable under EPA's regulations. The vehicle groupings for
defining these FEL caps differ somewhat from the groupings that apply
for the standards; we request comment on the need to reconcile these
different groupings.
    Evaporative emission credits under the proposed Tier 3 hot soak
plus diurnal standards would be calculated differently in the 2017
model year and the 2018 and later model years. For 2017 calculations
would be based on sales in the U.S. excluding California and the
section 177 states which have adopted the LEV III/ZEV programs. For
2018 and later model years it would be based on all 50 states.
Calculations would use the following equation: Credits = (fleet average
standard - fleet average FEL) x ``U.S. sales''. The ``fleet average
standard'' term here is the applicable Tier 3 hot soak plus diurnal
standard for the vehicle category from Table IV-18. The sales number
used in the 2018 and later MY calculation would be the number of
vehicles of the evaporative emission families in that category sold in
the U.S. which are subject to the Tier 3 evaporative emission
standards.\284\ Emission credits banked under the proposed evaporative
emission ABT program would have a five year credit life and would not
be discounted. This means the credits would maintain their full value
through the fifth model year after the model year in which they are
generated. At the beginning of the sixth model year after they are
generated, the credits would expire and could not be used by the
manufacturer. We are proposing to limit credit life so there is a
reasonable overlap between credit generating and credit using vehicles.
As mentioned above, for purposes of the compliance calculation,
allowance vehicles would have an FEL equivalent to the EPA emission
standard (Table IV-18) for their respective vehicle category.
---------------------------------------------------------------------------

    \284\ If EPA ultimately decided to continue the disaggregated
approach to fleet compliance calculations, we could potentially base
compliance with the proposed Tier 3 evaporative emission
requirements on U.S. sales (i.e., non-California and non-section 177
states).
---------------------------------------------------------------------------

    We request comment on all aspects of the ABT program. In
particular, we request comment on the structure of the proposed
evaporative emission ABT program and how the various provisions may
affect manufacturers' ability to utilize ABT to achieve the desired
evaporative emission-reductions in the most efficient and economical
way. We also ask for comment on basing ABT calculations on nationwide
sales in 2018 and later model years, even if there is a separate
calculation for California and the section 177 states.
d. Compliance Demonstration
    Demonstration of compliance with the evaporative emissions
standards would be done after the end of each model year. There are two
steps. In the first step, manufacturers would have to show compliance
with the phase-in percentages whether they used the primary phase-in
scheme or an alternative phase-in scheme. It is sales from these
families together with their respective FELs which would be used to
make the demonstration of compliance with the emission standard on
average within each vehicle averaging set. Compliant vehicles types for
these purposes would be the same as described in Section IV.C.2.a above
for projected sales. If the required sales percentages are not met by
direct sales or allowances, non-Tier 3 vehicles would have to be
identified to make up the shortfall. In the second step, using

the family emission limits, manufacturers would calculate the sales-
weighted average emission levels within each of the four vehicle
categories using U.S. sales.\285\ Manufacturers would be allowed to use
credits only within a defined averaging set. The averaging sets are:
(1) LDVs and LDT1s, (2) LDT2s, (3) LDT3s, LDT4s, and MDPVs, and (4)
HDGVs. These sales-weighted calculated values would have to be at or
below the emission standard for that vehicle category as proposed in
Table IV-18, unless credits from ABT are used. If the difference
between the standard and the sales-weighted average FEL is a positive
value this could be a banked credit available for future use. If the
difference between the standard and the sales-weighted average FEL is a
negative value this would be a credit deficit. Credit deficits would be
allowed to be carried forward. However, manufacturers would be required
to make up the deficit within the next three model years with credits
from vehicles in the same averaging set except as described below. As
discussed above, manufacturers would be required to identify and
include in the calculations vehicle families from each and any covered
category (see Table IV-18) whose total annual nationwide sales in the
given model year equals or exceeds the prescribed percentages. If the
inclusion of non-Tier 3 vehicles results in an exceedance of the hot
soak plus diurnal emission standard for that category of vehicles, the
credit deficit would have to be made up in a subsequent model year.
---------------------------------------------------------------------------

    \285\ The only exception here would be for vehicles not meeting
Tier 3 evaporative emission requirements in the 2022 MY as a result
of the use of previously earned allowances.
---------------------------------------------------------------------------

    Allowances could also be used to demonstrate compliance with the
percentage phase-in requirements and the vehicle category average
emission standard. For purposes of the percentage phase-in requirements
vehicles which have earned allowances are counted as compliant in the
percentage calculation. For purposes of the calculations for compliance
with the emission standard, allowance vehicles enters into the
evaporative emissions ABT calculation as having an emission rate
equivalent to the standard for that category of vehicle. Thus,
allowance vehicles would help in demonstrating compliance with the
percentage phase-in requirement (up to ten percentage points per model
year) and would help in reducing deficits since their calculation value
would be equivalent to the level of the standard. EPA asks for comment
on whether allowances should be permitted to be used across vehicle
categories during the transition years.
    As was discussed above, during the 2017-2019 model years EPA is
allowing manufacturers to meet the percentage phase-in requirements
using carryover certification data from vehicles certified to CARBs
Option 1 standards in the 2015 or 2016 model years. These vehicles may
have CARB Option 1 certification values slightly higher than those
proposed for EPA's Tier 3 program for the given vehicle and vehicle
category. Since the emission standard values in Tables IV-18 and IV-19
are very similar for any given vehicle category, for purposes of
simplification during the phase in, EPA proposes that any CARB Option 1
vehicles used in the 2017-2019 MY emission standard compliance
determination be entered into the calculation with the emission level
equivalent to the Tier 3 vehicle category in which the vehicle model
would otherwise fit. Furthermore, we are proposing not allowing
manufacturers to generate emission credits for families certified with
EPA based on carryover CARB PZEV evaporative emissions data using CARB
Option 1 as in Table IV-19. We are proposing not to include these
vehicles in the ABT program since the programs are not directly
comparable, and the structure of the current CARB ZEV program, which is
the genesis of most PZEV offerings, allows for a different number of
PZEV sales as a function of manufacturer size.
    As mentioned above, we are proposing to limit use of credits only
within a defined averaging set. Cost effective technology is available
to meet the proposed hot soak plus diurnal emission standards on
average within each of the vehicle categories in the averaging sets,
especially since the proposed standards are designed to accommodate
nonfuel hydrocarbon background emissions. Thus, further flexibility is
not needed. Moreover, we are proposing to constrain averaging to within
these sets because of equity issues for the manufacturers. We are
concerned that the four or five manufacturers with a wide variety of
product offerings in most or all of these categories would have a
competitive advantage over the majority of manufacturers which have
more limited product lines. This effect could be even more pronounced
if the number of evaporative families was considered, since larger more
diverse manufacturers have more models and thus more evaporative
families. EPA asks for comment on issues related to averaging sets.
    Manufacturer use of credits from different averaging sets to
demonstrate compliance would be permitted in limited cases. As noted
above, if a manufacturer has a credit deficit at the end of a model
year in a given averaging set, they would have to use credits from the
same averaging set during the next three years to make up the deficit.
However, if a deficit still exists at the end of the third year, we
propose that the manufacturer could use credits from a different
averaging set to cover the remaining deficit with the following
limitations. Manufacturers would be able to use credits from the LDV
and LDT1 averaging set to address remaining deficits in the LDT2
averaging set, and vice versa. We also are proposing that manufacturers
be permitted to use credits from the LDT3, LDT4, and MDPV averaging set
to address remaining deficits in the HDGV averaging set, and vice
versa. No other use of credit exchanges across different averaging sets
would be allowed. These restrictions are being proposed because of
equity concerns caused by the different nature and size of various
manufacturer product lines.
    During the program phase in there will be a declining percentage of
vehicles not yet covered by the proposed Tier 3 evaporative emission
requirements and thus covered by the current EPA requirements in 40 CFR
86.1811-09 and 86.008-10. These vehicles would need to be certified to
current EPA requirements or seek EPA certificates based on LEV II or
LEVIII emission data, subject to the certification fuel requirements
discussed below.
    For both the percentage phase-in and sales-weighted average
calculation steps above, we are proposing to base the calculation on
nationwide sales (excluding California and the section 177 states in
the 2017 MY) and annual nationwide sales beginning in the 2018 MY. We
believe this approach is consistent with the manufacturers' plans for
50-state vehicles. A program design which would enable a nationwide
program has been an important premise of this proposal. Furthermore,
this is simpler for the manufacturers and for EPA since it relieves the
need to project future model year sales or track past model year sales
at a disaggregated level. We recognize that decisions by manufacturers
on a national fleet versus a bifurcated approach such as exists today
(California and section 177-states separate from the rest of U.S.
sales) have

not yet been made.\286\ The CARB LEV III and EPA phase-in requirements
are identical beginning in 2018, so EPA sees little need for concern
that a nationwide-based accounting approach could lead to
disproportionate state by state impacts or the encouragement of
practices which would lead to any particular state or area not
receiving the anticipated emission reductions with this nationwide
approach to the calculation. However, for evaporative emissions for the
2017 MY we are proposing that percentage phase-in and sales be done on
a disaggregated level (i.e., California and section 177 states and the
remainder of the country) since at the present time the anti-
backsliding provisions of the LEV III evaporative emissions program
stays in place through the 2017 MY. This is being done differently for
the calculations for the early allowance program because these ``zero
evap'' vehicles are already counted in the pre-existing ARB program.
---------------------------------------------------------------------------

    \286\ If the decision is ultimately made to continue the
disaggregated approach to fleet compliance calculations, the
compliance with the proposed Tier 3 requirements would be based on
U.S. sales (non-California, non-section 177 states).
---------------------------------------------------------------------------

    As was discussed above, manufacturers not meeting the percentage
phase-in requirements would need to include non-Tier 3 vehicles in the
count and include their emissions in the overall calculation of
compliance with the hot soak plus diurnal standard and resolve
shortfalls in compliance with the emission standard with future
reductions, earned allowances, or credits. Resolving this sales
percentage shortfall problem becomes a bit more complicated for the
2017 MY 20 percent option upon which EPA is seeking comment, because it
would require that 20 percent of vehicles meet the proposed Tier 3
evaporative emission requirements and that 20 percent meet the proposed
leak emission standard. These may or may not be the same vehicles,
(e.g., non-Tier 3 vehicles could end up in the end of year calculation
and we are seeking comment on whether to allow the two 20 percent
requirements to be allowed to be met on different vehicles). As a means
to resolve this potential problem, EPA asks comment on a provision
which would require that any shortfall of either of the 20 percent
values (Tier 3 evaporative or leak emission standard) for the 2017 MY
be covered by future sales of vehicles meeting the Tier 3 evaporative
emission requirements in excess of the evaporative emission percentage
sales requirement for that MY or some combination of MYs. For example,
if a manufacturer were 5 percentage points short in the 2017 MY, then
it would have to accelerate sales of vehicles meeting Tier 3
evaporative emission requirements in the 2018-2021 MYs to cover the 5
percentage points (e.g., 65 percent in 2018 instead of 60 percent or 63
percent in 2018 MY and 62 percent in the 2019 MY, etc.).
e. Small Volume Manufacturers
    As another flexibility, we are proposing that small volume
manufacturers, those with average annual nationwide sales of 5,000
units or less, be permitted to delay meeting the proposed Tier 3
evaporative emission standards, including the requirement to use EPA
certification test fuel, until the 2022 MY (see Section IV.E.5 below
for a discussion of our proposed 5,000 vehicle threshold). This would
include the hot soak plus diurnal standards, the canister bleed
emission standard, and the leak emission standard. In the interim,
these vehicles would have to meet the current evaporative and refueling
emission standards. The initial determination of whether a manufacturer
is under the 5,000 unit threshold would be based on the three year
average of actual nationwide sales for MYs 2012-2014. This allowance
would not be affected if a qualifying manufacturer's nationwide sales
later exceeded that value before 2022. Similarly, new market entrants
(not in the market in the 2012 MY) with projected sales of less than
5,000 units could be covered by the small volume manufacturer
provisions. However, in this case if actual running average nationwide
sales exceeded 5,000 units per year in any three consecutive model
years they would have to meet the Tier 3 evaporative requirements in
the third model year thereafter. For example, if a new market entrant
in 2015 projected nationwide production of 4,000 units per year and the
average of actual values in 2015-2017 exceeded 5,000 units per year
they would have to meet Tier 3 evaporative requirements by the 2020 MY.
f. High-Altitude Requirements
    We adopted the most recent vehicle evaporative emission standards
in 2007.\287\ These newest standards apply only to testing under low-
altitude conditions.\288\ In that rule, we decided to continue to apply
the previous ``Tier 2'' standards for testing under high-altitude
conditions. This was necessary to achieve an equivalent level of
overall stringency for high-altitude testing. This was intended to
account for the various effects of altitude and lower atmospheric
pressure on vapor generation rates, canister loading and purging
dynamics, and other aspects of controlling evaporative emissions due
primarily to lower air and vapor concentrations in air. While it is
important for vehicles to have effective emission controls at high
altitudes, we do not want the high-altitude standards and test
procedures to dictate the fundamental design of the Tier 3 evaporative
emission control systems since the high altitude vehicle population is
only about five percent of the national total. Therefore, we believe it
is appropriate to address this goal by applying the current EPA 2-day
low altitude evaporative emission standards and requirements for high-
altitude testing. The vehicle categories for the high altitude
standards in this proposed rule are the same as for the low altitude
standards. The proposed standards are presented below in Table IV-20.
This would both reduce emissions at high altitude and again create a
requirement to confirm that emission controls function effectively at
high altitude without forcing manufacturers to apply altitude-specific
technologies. Furthermore, the leak emission standard proposed in
Section IV.C.5.b below would apply equally at low and high altitude
testing.
---------------------------------------------------------------------------

    \287\ 72 FR 8428 (February 26, 2007).
    \288\ High-altitude conditions means a test altitude of 1,620
meters (5,315 feet). Low altitude conditions means a test altitude
less than 549 meters (1,800 feet).

    Table IV-20 Proposed High-Altitude Evaporative Emission Standards
                                [g/test]
------------------------------------------------------------------------
                                                    Highest hot soak +
                                                   diurnal level (over
                Vehicle category                   both 2-day and 3-day
                                                     tests) (g/test)
------------------------------------------------------------------------
LDV, LDT1......................................                     0.65
LDT2...........................................                     0.85
LDT3, LDT4.....................................                     1.15
MDPV...........................................                     1.25
HDGVs <= 14,000 lbs GVWR.......................                     1.75
HDGVs > 14,000 lbs GVWR........................                      2.3
------------------------------------------------------------------------

    A few additional points should be noted about our proposed Tier 3
high altitude evaporative emissions control program. First, by
proposing to apply the current low altitude evaporative emission
standards and requirements by category for high-altitude, we are
proposing not to include the canister bleed test and emission standard.
These vehicles would have to meet the canister bleed emission standard
at low altitude and any adjustment to meet the

standard at high altitude to account for canister adsorption and
desorption effects of higher altitudes would result in fundamentally
the same technology and increase the testing burden, but not
necessarily lead to more emissions control. Therefore, we believe the
low-altitude canister bleed test is sufficient for achieving the
proposed level of emission control for operation in both low-altitude
and high-altitude conditions. Second, for vehicles certified with FELs
above or below the applicable standard for testing at low altitude, we
propose that the same differential apply to the FELs for high-altitude.
For example, if an LDV was certified with an FEL of 0.400 g instead of
the 0.300 g standard, the high-altitude FEL would be 0.75 g (0.65g +
0.10g). This high-altitude FEL would not be used for any emission-
credit calculations, but it would be used as the emission standard for
compliance purposes. Third, gasoline RVP for certification test fuel
would be set at 7.8 RVP with 15 percent ethanol, as specified in
Section IV.D. Finally, we are proposing a minor adjustment to the high
altitude test procedures. Today, the 2- and 3-day test procedures apply
equally at low and high altitude. We are proposing to keep that
requirement but to allow for an adjustment of 5[emsp14][deg]F in the
temperatures related to the running loss test within the 3-day test
cycle. Thus, the applicable fuel and ambient temperatures at Sec.
86.134-96 (f) and (g) would 90  5[emsp14][deg]F instead of
95  5[emsp14][deg]F for high altitude testing. EPA believes
this is appropriate given the differences in atmospheric conditions at
low versus high altitude and will still result in equivalent control of
running loss emissions at higher altitudes. We request comment on the
alternative approach of keeping test temperatures the same, but
omitting the 3-day test cycle for testing at high altitude. This would
effectively establish the 2-day test cycle as a sufficient means of
demonstrating that emission control systems continue to operate
properly at high altitude.
    As mentioned above, emission data from vehicles meeting the current
CARB zero evap and useful life requirements could be used to qualify
that vehicle to meet the Tier 3 evaporative emission regulations for
the 2017-2019 MYs. To qualify for a federal certificate, the vehicle
would also have to meet the Tier 3 high altitude evaporative emission
requirements. While CARB requires vehicles to meet EPA high altitude
requirements, we ask for comment on the need for and value of an
interim option which would permit manufacturers to gain such
certification by an engineering demonstration that the vehicle would
comply at any altitude rather than by performing additional testing.
g. Technological Feasibility
    The basic technology for controlling evaporative emissions was
first introduced in the 1970s. Manufacturers routed fuel tank and
carburetor vapors to a canister filled with activated carbon, where
vapors were stored until engine operation allowed for purge air to be
drawn through the canister to extract the vapors for delivery to the
engine intake. Over the past 30 years, evaporative emission standards
have changed several times, most notably in the mid-1990s when enhanced
evaporative controls were required to address 2- and 3-day diurnal
emissions and running losses. Refueling emission controls were added
with phase-in beginning in the 1998 MY. Almost universally
manufacturers elected to integrate evaporative and refueling emission
control systems. In the mid-2000s more stringent evaporative emission
standards with E10 durability gasoline led to the development and
adoption of technology to identify and eliminate permeation of fuel
through fuel tanks, fuel lines, and other fuel-system components.
i. Hot Soak Plus Diurnal
    The current baseline technology for LDVs, LDTs, and MDPVs is a
properly designed and assembled fuel/evaporative system for controlling
emissions over the 2- and 3-day test sequences to meet the current
standard of 0.650 grams/test. This involves activated carbon canisters
which capture gasoline vapors, with engine calibrations designed to
maximize canister purge over the test sequence. Fuel systems generally
include widespread use of various grades of permeation-resistant
materials.
    The anticipated control technologies to comply with the proposed
hot soak plus diurnal evaporative emission standards include an
improved carbon canister designs to even better capture vapor emissions
from the canister, air intake designs to prevent the escape of unburned
fuel from the engine's crankcase, various upgrades to further limit
potential micro-sized leaks, and further steps to reduce permeation
rates. Applying these new or improved technologies will allow
manufacturers to meet the proposed 300 mg standard for LDVs/LDT1s. The
proposed evaporative emission standards are slightly higher for larger
vehicles to account for potentially higher background emissions and in
some cases larger surface area components, but the baseline and
anticipated control technologies follow a very similar path. These
baseline and control technologies are described further in the rest of
this section.
    Current evaporative canisters use high working-capacity activated
carbon, usually with multiple compartments, to optimize vapor loading
and purging behavior. These canisters sometimes employ carbons of
different working capacities within each chamber. Testing indicates
that the total canister adsorption capacity in grams of gasoline vapor
is generally dictated by the requirements of the refueling emission
test and standard rather than the evaporative emission test (either the
2- or 3-day sequence).
    Manufacturers have identified the engine's intake system as another
source of evaporative emissions. These result from crankcase vapors and
from unburned fuel from injectors, or sometimes from an injection event
that occurred shortly before engine shutdown. We estimate a typical
emission rate of about 40 mg associated with each engine shutdown
event; however, since the actual emission rates depend on timing of
individual injection events and cylinder position at shutdown, baseline
emission rates can vary significantly. These vapors must follow a
contorted path before reaching the ambient air, which would generally
cause these emissions to show up during the first day of the diurnal
test rather than the hot soak test. One way to prevent these emissions
is to add activated carbon to the air intake downstream of the air
filter, typically in the form of reticulated foam coated with activated
carbon. This device would have only a few grams of working capacity and
would be designed to purge easily to ensure that the vapor storage is
available at engine shutdown. This carbon insert would almost
completely eliminate any vapor emissions from the air intake system.
    Manufacturers wanting to avoid adding any specialized emission
control component to control evaporative emissions from the air intake
could pursue alternative approaches. First, it is possible to allow the
engine to continue rotating for 2-3 revolutions after engine shutdown
to sweep any hydrocarbon vapors from the intake system into or through
the cylinder. These vapors could be burned in the cylinder, oxidized at
the catalyst, or stored until the engine starts again. This may still
allow for a small amount of residual vapor release, but this should be
a very small quantity. Vehicle owners

would be unlikely to notice this amount of engine operation after
shutdown. Second, to the extent that manufacturers use direct
injection, there should be no fuel vapor coming from the intake system.
Any unburned fuel coming from the injectors would be preserved in the
cylinder or released to the exhaust system and the catalyst. A small
amount of crankcase vapor might remain, but this would likely not be
enough to justify adding carbon to the intake system.
    Fuel tanks are designed to limit permeation emissions. Fuel tanks
are typically made of high-density polyethylene with an embedded
barrier layer of ethyl vinyl alcohol (EvOH) representing about 1.8
percent of the average wall thickness. The EvOH layer is effective for
reducing permeation emissions. Recent developments in production
processes have led to improved barrier coverage around the ends of the
tank where the molded plastic is pinch-welded to form a closed vessel.
We are expecting manufacturers to increase the EvOH barrier thickness
to about 3 percent of the average wall thickness to provide a more
uniform barrier layer, to provide better protection with ethanol-based
fuels, and to improve permeation resistance generally. These changes
are expected to decrease emission rates over the diurnal test from
about 40 mg per day to 15 mg per day from the fuel tank assembly or
less.
    Fuel lines are also already designed for low permeation rates. The
biggest portion of fuel and vapor lines are made of metal, but that may
still leave several feet of nonmetal fuel line. There may be
development of new materials to further reduce permeation rates, but it
is more likely that manufacturers will adjust the mix of existing types
of plastic fuel lines to achieve the desired performance at the lowest
possible price.
    The bigger area of expected development with respect to fuel lines
is to re-engineer fuel systems to further reduce the number of
connections between fuel-system components and other fuel-line
segments. Today these systems may involve more than the optimum number
of connections and segments due to assembly and production
considerations or other factors. Designing the fuel system more
carefully to minimize connection points will limit possible paths for
fuel vapors to escape. This would reduce emission rates and it should
also improve system durability by eliminating potential failure points.
A broader approach to addressing this source of emissions is to
integrate designs and to move fuel-system components inside the fuel
tank, which eliminates the concern for vapor emissions and permeation
from those components and connections.
    A remaining area of potential evaporative emissions is the
connection between the fill neck and the fuel tank. Manufacturers can
reduce emissions by perhaps 10 mg per day by making this connection
permeation-resistant. The challenge is to design a low-cost solution
that is easily assembled and works for the demanding performance needs
related to stiffness/flexibility. The best approach is likely either to
use mating parts made from low-permeation materials, or to use
conventional materials but cover this joint with material that acts as
a barrier layer.
    Purge rates are currently designed to flow relatively large volumes
of outside air through the canister when the purge solenoid is
activated. This involves using available manifold vacuum to create
purge flow, with limits in place to avoid drawing too much unmetered
fuel vapor from the canister. Tightening the evaporative emission
standard would lead manufacturers to address remaining emission sources
from micro-size leak points, permeation, and diffusion, as noted above.
Since the amount of additional vapor being captured by the carbon
canister is small and the test procedure is not changing, we do not
expect the change in standards to drive changes in purge strategy,
rates, or canister capacity. Nonetheless, vehicle system and engine
changes to improve fuel economy could impact future purge strategies.
Thus, as part of this approach, manufacturers may incorporate designs
to reduce vapor volume/mass directed to the canister and thus
potentially reduce the purge air volume requirements. In addition,
canister designs can be optimized to increase the effectiveness of a
given volume of purge air. This could involve selecting different
combinations of carbon characteristics and canister architecture types
and by adding features to add heat (or preserve heat) in the canister
during a purge event. It is also possible that fuel economy strategies
which impact purge volume may lead some manufacturers to add vacuum
pumps to supplement engine-based purge on some vehicle models in the
future.
    It is worth noting that there may be some models where
manufacturers incorporate hardware or another control technique that
may not be widely used across by all manufacturers or across all
models. This is especially true for this set of proposed emission
control requirements since we are considering such a wide array of
basic vehicle and engine designs. Also, future vehicle/engine systems
such as hybrids may have more unique challenges in areas such as the
diurnal fuel tank vapor load sent to the activated carbon canister and
subsequent purging of those vapors. In response to this challenge,
manufacturers may employ techniques to reduce fuel tank vapor
generation and/or to enhance purge efficiency. Hardware such as a vapor
blocking valve or other techniques to enhance purge efficiency from the
canister through heating may be employed to a limited degree.
    The technologies discussed above are in use to varying degrees on
many of the CARB PZEV zero evap vehicles mentioned above. Taken
together, we believe these technologies provide manufacturers with
effective tools for reducing emissions sufficiently to meet the
proposed evaporative emission standards.
ii. Canister Bleed Emission Standard
    More stringent evaporative emission standards have led to more
careful measurements, which led manufacturers to discover that 80 mg or
more of fuel vapor would diffuse from the canister vent as a result of
the normal redistribution of vapors within the activated carbon while
the vehicle is at rest. The emission rate depends on the tank volume,
its fill quantity, and the size and architecture of the canister and
the characteristics of the carbon itself. While the biggest effect of
this vapor distribution is a uniform concentration within the canister,
it can also cause vapors to escape through the canister vent even
without continued canister loading that would result from fuel tank
heating. These are referred to as canister bleed emissions. These
emissions occur to some degree during the 2- and 3-day evaporative
emissions test, but a separate standard is needed if the goal of near
zero fuel vapor emissions is to be achieved.
    The design to address this concern is a supplemental ``scrubber''
canister (or canister compartment) with a very low working capacity
carbon. Adding 100 or 200 ml of this type of carbon near the canister
vent provides a margin of ``reserve capacity'' to capture diffusion
losses from the canister. Since this extra carbon has low working
capacity and it purges readily, it is typically cleared of hydrocarbon
vapors and ready to perform its function after any amount of engine
operation or even with natural back purge which occurs when the fuel in
the tank cools. This scrubber element is expected to eliminate all but
5-10 mg of emissions from the evaporative canister over the measurement
procedure.

iii. Leak Emission Standard
    Vapor leaks in the vehicle fuel/evaporative system can arise from
micro-cracks or other flaws in various fuel/evaporative system
component structures or welds, problems with component installations,
and more generally from connections between components and fuel lines
and vapor lines. Because these emissions from these areas would occur
in the 2-3 day evaporative emissions test if the problems were present,
manufacturers have taken steps to address these potential problem areas
as part of their overall evaporative emissions control strategy. Since
the 2- and 3-day hot soak plus diurnal standards are proposed to become
more stringent and leak emissions occur during the evaporative
emissions test, we expect manufacturers to take the measures described
above in Section IV.C.2.g.i. These include reducing connections,
improving the quality of fuel and vapor line connections, use of
improved component materials and revised installation practices.
Manufacturers could also review their OBD leak warranty data and
related information from OBD queries to help inform their strategies.
One of the key reasons for proposing a leak emission standard is to
promote the continuing development of designs, part production
techniques, and assembly practices which will yield less in-use
emissions deterioration and improved in-use emissions performance. EPA
believes this focus on in-use durability is important because a vehicle
with even a small leak, e.g., the size of the 0.020-0.040 inch orifice
diameter monitored by OBD systems would likely emit above the proposed
hot soak plus diurnal evaporative emission standard in use.
3. Heavy-Duty Gasoline Vehicle (HDGV) Requirements
a. Overview of the Proposal for HDGVs
    As presented above, EPA is proposing to include HDGVs within the
Tier 3 evaporative emissions program. The proposed hot soak plus
diurnal and canister bleed test emission standards that would apply to
these HDGVs are as presented in Table IV-18 and the high altitude
standard is presented in Table IV-20. These vehicles would be included
in the averaging calculation beginning in the 2018 MY and would be
eligible for creating and using allowances and credits as discussed
above. Furthermore, for the reasons discussed below, EPA is proposing
that HDGVs equal to or less than 14,000 lbs GVWR be required to meet
the refueling emission standard by the 2018 MY.
b. Background on the HDGV Sector
    HDGVs are generally gasoline-powered vehicles with either a GVWR of
greater than 8,500 lbs, or a vehicle curb weight of more than 6,000
lbs, or a basic vehicle frontal area in excess of 45 square feet.\289\
HDGVs are predominantly but not exclusively commercial vehicles, mostly
trucks and other work type vehicles built on truck chassis. EPA often
discusses HDGVs in three basic categories for regulatory purposes
according to their GVWR class. These include Class 2b (8,501-10,000 lbs
GVWR), Class 3 (10,001-14,000 lbs GVWR), and Class 4 and above (over
14,000 lbs GVWR). These are further sub-categorized into complete and
incomplete vehicles.\290\ Class 2b HDGVs are mostly produced by the
manufacturers as complete vehicles and are very similar to lower GVWR
LDTs of the same basic model sold by the manufacturers. Class 3 HDGVs
are also built from LDT chassis with fuel system designs that are
similar to their Class 2b and LDT counterparts, but these are on some
occasions sent to secondary manufacturers as incomplete vehicles to
attach a load carrying device or container. EPA estimates that more
than 95 percent of Class 2b/3 vehicles are complete when they leave the
original equipment manufacturer (OEM). Class 4 and above HDGVs are
built on a more traditional heavy-truck chassis and in most cases leave
the OEM as an incomplete vehicle. For Class 2b/3 vehicles, it is common
to certify the vehicle for emissions purposes (exhaust, evaporative,
etc) as a full chassis, while for Class 4 and above the vehicle is
certified as a chassis for evaporative emissions while the engine is
dynamometer certified for exhaust emissions.
---------------------------------------------------------------------------

    \289\ MDPVs also meet the definition of HDVs, but they are
classified separately for evaporative and refueling emission
purposes. See 40 CFR 86.1803-01.
    \290\ Vehicles may be complete or incomplete vehicles. A
complete HDGV is one that has the primary load carrying device or
container (or equivalent equipment) attached, normally by the
vehicle OEM. An incomplete vehicle is one that does not have the
primary load carrying device or container (or equivalent equipment)
attached when it is first sold. This may include vehicles sold to
secondary vehicle manufacturers.
---------------------------------------------------------------------------

    For LDVs and LDTs, the current EPA evaporative and refueling
emission test procedures are the same for all vehicle categories and
the emission standards are of a similar but not always identical
stringency, within the subclasses. However, this is not true for HDGVs.
For HDGVs, the level of the evaporative emission standards and the test
procedures vary by category and the refueling emission control
requirements are also different. There are several reasons for these
differences, including variations in the size, design, and other
properties of the basic fuel system, the dimensions of the vehicles,
and the potential for actions of secondary manufacturers to impact the
fuel system. There are many fuel system similarities between Class 2b/3
HDGVs and heavy LDTs, but fewer similarities between heavy LDTs and
HDGVs in Class 4 and above.
    Over the past 15 to 20 years, there have been several notable
changes in HDGV products and market that have influenced the
application of evaporative and refueling emission control requirements
and may impact potential new or revised requirements going forward.
Most noteworthy among these are the increased use of diesel engines
across all weight classes and the emergence of better defined market
segments for primary OEMs and secondary manufacturers.
    The increased use of diesel engines has reduced overall HDGV sales
and brought about a consolidation of manufacturer HDGV product
offerings. For Class 2b/3 HDGVs, these are now all derived from LDT
chassis and have the same basic fuel system and engine characteristics.
This has led EPA to extend the light-duty evaporative and refueling
test procedures and emission standards to the Class 2b/3 HDGVs, when
applicable. In a rule promulgated in 2000, EPA required manufacturers
to certify these HDGVs using light-duty test procedures. Also, in this
same rule, EPA extended the vehicle refueling emission standards to
complete Class 2b vehicles. These actions were technically appropriate
because of the similarities between the LDT and Class 2b HDGVs and fuel
systems and the large fraction of complete Class 2b HDGVs produced by
the vehicle manufacturers. Today, fuel systems for Class 3 HDGVs are
comparable those for Class 2b HDGVs, so it is reasonable and
technically feasible to extend the Class 2b refueling emission
requirements to Class 3 HDGVs.
    Class 4 and heavier HDGVs still play a small but important role in
the traditional truck and heavy-duty vehicle markets. These vehicles
are sometimes distinctly different from Class 2b/3 vehicles in terms of
testing, chassis designs, and fuel system characteristics; secondary
manufacturers also play a larger role in the overall completion of the
vehicle. For these vehicles, the engines are certified for emissions on
an engine dynamometer while the evaporative emissions are certified
separately on the vehicle chassis. Furthermore, these vehicles are
larger

dimensionally (which often means longer fuel and vapor lines) and have
larger volume fuel tanks (sometimes two), which may be mounted on the
underbody or side-rail. It is common for a secondary manufacturer to
complete the vehicle by adding the cargo container or other working
equipment box or package (e.g., small cargo truck or tow truck) and in
some cases to reconfigure components. While the extrapolation of
refueling emission control technology is conceptually straightforward,
in some cases there may be unique technical issues related to
implementing refueling emission controls for these heavier HDGVs
relative to Class 2b/3 HDGVs and LDTs.
    Based on these considerations, EPA is proposing that the refueling
emission standards in Sec.  86.1816-05 to apply to Class 3 HDGVs as
well. This is appropriate because the fuel and evaporative control
systems on these vehicles are very similar to those on their slightly
lighter-weight Class 2b counterparts, and in some cases Class 3 HDGVs
are already designed to meet this proposed requirement. EPA is
proposing that this requirement be met beginning in the 2018 MY. EPA is
also proposing that manufacturers be permitted to comply as early as
the 2015 MY to earn on a one-to-one basis allowances which could be
used to phase-in the Class 3 refueling emission control requirement or
as an allowance under the Tier 3 evaporative emission program. EPA
believes this is appropriate since the expected daily average reduction
in vehicle refueling emissions for this class of vehicles is large
relative to the reduction in evaporative emissions expected under Tier
3. Any certifications, including those done early, must use EPA Tier 3
test procedures and certification test fuels.
c. Other Potential Program Elements for HDGVs
    EPA is seeking comments on several other programmatic elements
related to the Tier 3 evaporative and refueling emission control
proposal.
    First, even if we do not revise the current evaporative emission
standards for these vehicles and they are not required to control
refueling emissions, we are seeking comment on requiring manufacturers
to certify their evaporative emissions using Tier 3 certification test
fuel. Tier 3 certification test fuel would provide equivalent or better
emissions control as compared to current certification test fuel in
terms of the fuel quality impact on emission control system designs to
meet the existing evaporative emission standards and would provide
equivalent or better in-use performance. Requiring this new
certification test fuel has the potential to add efficiency to the
certification process since manufacturers could certify one system for
EPA and CARB for each evaporative family. Since incomplete vehicles and
those over 14,000 lbs GVWR often do not use the same test vehicle/
engine for evaporative and exhaust emission testing, we seek comment on
whether a requirement for vehicle evaporative and/or refueling emission
certification on Tier 3 test fuel would technically necessitate engine
exhaust emission certification on Tier 3 test fuel.
    Second, as mentioned in Section IV. B., EPA is also seeking comment
on requiring the use of Tier 3 certification test fuel for HDGVs which
are engine-dynamometer certified, not chassis-certified, for exhaust
emissions. This would potentially include all engine families certified
for use in HDGVs above 8,500 lbs. GVWR. We are seeking comment on this
change because we believe it may be the best and most representative
technical approach for the future in the context of the engine/emission
control system/fuel system design and performance and fuel quality.
Overall, we believe this change to the certification test fuel for
HDGVs would provide equivalent or better emissions control for the
regulated pollutants as compared to current certification test fuel, in
terms of the impact of fuel quality on emission control system designs
and in-use performance, and may also simplify manufacturers' testing
operations by providing for a single test fuel. We are also seeking
comment on putting this requirement in place in the 2020-2022 MY time
frame. Consistent with the approach proposed in Section IV.D.4 for
light- and heavy-duty vehicles, we are committed to the principle of
ensuring that any change in test fuel for heavy-duty engines would not
affect the stringency of either the fuel consumption or GHG emissions
standards. As part of the separate rulemaking discussed in Section
IV.D.4, we would expect to establish the appropriate test procedure
adjustment for HD engine fuel consumption standards and to determine
the need for any test procedure adjustment for GHG emissions standards
based on the change in certification test fuels.
    Third, to simplify the evaporative emission regulations for HDGVs
and to bring them more in line with the current structure of the
product offerings in this sector, we are proposing to permit
evaporative emissions certification by engineering analysis for
vehicles above 14,000 lbs GVWR (instead of above 26,000 lbs GVWR as is
permitted in the current regulations). These HDGVs would remain subject
to the emission standards when tested using the specified procedures.
This is the same cut point allowed by CARB and would allow for one
certification method. Furthermore, for HDGVs over 14,000 lbs GVWR, we
request comment on taking an additional step to rely even further on
design parameters and engineering analysis. Under this approach,
manufacturers would need to demonstrate that the design of their purge
strategy, canister capacity, and overall control system would control
emissions to the same degree as similar (or comparable) Class 2b or
Class 3 vehicles that meet emission standards when tested over the
established measurement procedures. The standard would be a performance
standard in that the manufacturer could use any design that met the
criteria of controlling emissions to the same degree that occurs in
vehicles that meet the emissions standard. However, unlike the proposed
approach, compliance with the standard would be based solely on an
engineering review of the design. Compliance would not be determined by
measuring performance on the emissions test. This would take into
account the limitations in managing any significant degree of testing
with these over-size vehicles. In particular, we request comment on the
enforceability of taking the approach of a design standard.
    Fourth, we are proposing a revised description of evaporative
emission families that does not reference sealing methods for
carburetors or air cleaners as this technology is now obsolete for
heavy-duty gasoline engines.
    Fifth, we also seek comment on the implications on these
evaporative emission standards were we to require the certification
test fuel to be 10 psi RVP E10 as discussed below in Section IV.D.1.
    Sixth, we are proposing to clarify how evaporative emission
standards affect engine manufacturers and proposing more descriptive
provisions related to certifying vehicles above 26,000 lbs GVWR using
engineering analysis. These improved descriptive provisions would apply
to vehicles above 14,000 GVWR lbs if the proposed change in GVWR cut
point for engineering analysis certification is finalized.
    Finally, EPA is asking for comment on several other provisions
related to the heavier HDGVs (over 14,000 lbs GVWR). First, if we do
not include these heavier HDGVs in the Tier 3 final rule requirements,
we are asking comment on whether manufacturers should be

able to voluntarily certify any HDGVs not covered by the rule to the
same requirements as being proposed for Class 2b/3 HDGVs, and through
this action earn allowances and credits for use within the Tier 3
program as discussed above for other vehicles. This would include both
evaporative and refueling emissions standards. Second, EPA also asks
comment on whether there should be a provision to permit HDGVs over
14,000 lbs GVWR to be grouped with those between 10,001 and 14,000 lbs
GVWR for purposes of complying with evaporative and refueling emission
control standards and related provisions. In these cases, we would
expect these HDGVs to meet all the requirements applicable to the group
in which they are being included (e.g., useful life, OBD, etc.).
4. Test Procedures and Certification Test Fuel
a. Review and Update of Testing Requirements
    EPA adopted the current test requirements for controlling
evaporative emissions in 1993.\291\ Those changes included: (1) Diurnal
testing based on heating and cooling the ambient air in the SHED \292\
instead of forcing fuel temperatures through a specified temperature
excursion; (2) repeated 24-hour diurnal measurements to capture both
permeation and diurnal emissions; (3) high-temperature hot soak
testing; (4) high-temperature running-loss measurements with a separate
standard, including controlled fuel temperatures according to a fuel-
temperature profile developed for the vehicle; and (5) canister
preconditioning to ensure that vehicles could effectively create
canister capacity to prepare for several days of non-driving.
---------------------------------------------------------------------------

    \291\ 58 FR 16002 (March 24, 1993).
    \292\ SHED is the Federal Register acronym for sealed housing
for evaporative determination. The SHED is the enclosure in which
the evaporative emissions are captured before measurement.
---------------------------------------------------------------------------

    These test procedures are generally referred to as ``enhanced
evap'' testing. EPA adopted these ``enhanced evap'' test procedures in
coordination with CARB. The test requirements include two separate test
sequences to demonstrate the effectiveness of evaporative emission
controls. The ``two-diurnal sequence'' involves canister loading to
two-gram breakthrough, followed by driving for the exhaust test (about
31 minutes), a hot soak test, and two days of cycled ambient
temperatures. The ``three-day sequence'' involves canister loading with
50 percent more vapor than needed to reach breakthrough, followed by
driving for the exhaust test, driving for the running loss test (about
97 minutes total), a high-temperature hot-soak test, and three days of
cycled ambient temperature.
    The 2-day sequence was intended primarily to insure a purge
strategy which would create enough canister capacity to capture two
days of diurnal emissions after limited driving. The two-day
measurement period was effective for requiring control of permeation
and other fugitive emissions. The 3-day sequence was intended to
establish a design benchmark for achieving adequate canister storage
capacity to allow for several days of parking on hot summer days, in
addition to requiring vehicle designs that prevent emissions during
high-temperature driving and shutdown conditions.
    After adopting these evaporative test procedures, we set new
standards for refueling emissions control which called for onboard
refueling vapor recovery (ORVR).\293\ Manufacturers have typically
designed their ORVR systems to be integrated with their evaporative
controls, using a single canister and purge strategy to manage all fuel
vapors vented from the fuel tank. Due to the magnitude of the refueling
emission load and the manner in which the load rates affect activated
carbon capture efficiency, it has become clear that ORVR testing with
these integrated systems serves as the benchmark for achieving adequate
canister storage capacity.
---------------------------------------------------------------------------

    \293\ 59 FR 16262 (April 6, 1994).
---------------------------------------------------------------------------

    In the nearly 20 years since adopting these test procedures,
manufacturers have made great strides in developing designs and
technologies to manage canister loading and purging and to reduce
permeation emissions. Except as discussed below, we are not proposing
to change the test procedures for demonstrating compliance with the
proposed Tier 3 emission standards.
    As described above, we are proposing to adopt a new standard based
on measured values over a ``canister bleed test,'' which is intended to
measure only fuel vapors which diffuse from the evaporative canister.
CARB developed this procedure as a means of setting a standard that
would not be affected by nonfuel background emissions. This procedure
is a variation of the established two-day test sequence. The canister
is preconditioned by purging and loading to breakthrough, then attached
to an appropriate test vehicle for driving over the duty cycle for the
exhaust test. The canister is then attached to a fuel tank for
measurement. After a stabilization period, the tank and canister
undergo two days of temperature cycling. Canister emissions are
measured using a flame ionization detector (FID), either using a
conventional SHED approach or by collecting emissions in a bag and
measuring the mass. Rather than repeating CARB's regulations, we are
proposing to incorporate those regulations by reference into the CFR.
This will avoid the possibility of complications related to minor
differences that may occur with separate test procedures.
    CARB also adopted a fuel system ``rig test'' as an optional
approach to demonstrate control of evaporative emissions without the
effects of the nonfuel hydrocarbon emissions that are seen in testing
the whole vehicle in the SHED. We generally expect manufacturers to
comply with the proposed EPA requirements which include the canister
bleed test and emission standard instead of CARB Option 1 which
includes the rig test and emission standard. However, since we are
proposing to accept CARB Option 1 certifications for the 2017 through
2019 model years, we are also proposing to incorporate by reference
CARB's rig test into the CFR to accommodate those manufacturers that do
in fact rely on this approach.
    Also, as discussed further below, we are proposing to adopt a new
leak test procedure which would be used to measure leak rates for the
proposed leak emission standard. The leak test standard test procedure
is contained in the proposed regulatory text. Further detail can be
found in the draft Regulatory Impact Analysis (Appendix to Chapter 1).
    Manufacturers have raised a pair of related concerns regarding the
current test procedures. First, hybrid vehicles and new engine designs
for meeting fuel economy standards and CO2 emission
standards increase the challenge of maintaining an adequate purge
volume to prepare vehicles for the diurnal test. For hybrid vehicles
this is related to the amount of time the engine is running. For other
technologies this is related to the trend toward decreasing available
vacuum in the intake manifold, which is the principal means of drawing
purge air through the canister. Second, preconditioning the canister by
loading to breakthrough serves as a disincentive for some control
strategies that might otherwise be effective at reducing emissions,
such as designs involving greater canister capacity or better
containment of fuel vapors inside the fuel tank. In addition, we have
learned from studying in-use emissions and in-

use driving behaviors and usage patterns that it is not uncommon for
vehicles to go for an extended period with little or no opportunity to
purge the canister.
    We request comment on an optional adjustment to the test procedure
intended to address these three concerns. In this alternative, for
designs involving pressurized tanks, manufacturers would determine an
alternative vapor load to precondition the canister before the exhaust
test. If, for example, a fuel system is designed to stay sealed up to 1
psi and to vent vapors to the canister if rising temperatures trigger a
pressure-relief valve, the manufacturer could quantify the actual vapor
load to the canister during three consecutive days of cycling through
diurnal test temperatures. This three-day vapor load would be the
amount of fuel vapor used to precondition the canister (loaded at the
established rate of 15 grams per hour). This canister loading may also
involve butane instead of fuel vapor, but we would likely require a
greater mass of butane to account for the fact that it is easier to
remove the butane from the activated carbon in the canister. This
approach would be flexible to accommodate any design target for
pressurizing fuel tanks. Canister preconditioning for the ORVR test
(for integrated and nonintegrated systems) would remain unchanged.
b. Test Fuel
    EPA is proposing to change the certification test fuel
specifications as described in Section IV.D. Here we discuss some
implications for evaporative and refueling emissions testing. We are
proposing to revise the certification test fuel specification
(including durability fuel) in conjunction with the proposed Tier 3
standards, principally to include ethanol and reduce sulfur such that
the test fuel better aligns with the current and projected in-use fuel.
Any Tier 3 evaporative emission certification would have to use Tier 3
certification test fuel and test procedures. This could be done as
early as the 2015 MY and would be required for all vehicle models by
the 2020 MY. We are further proposing to apply the new test fuel at the
same time to ORVR testing. Therefore, beginning in the 2017 MY if
manufacturers do any new testing to demonstrate compliance with the
proposed Tier 3 evaporative emission standards, they would need to
submit test data to demonstrate compliance with the refueling emission
standards using the new certification test fuel as well as the leak
(when applicable), refueling, canister bleed, and high altitude testing
requirements and emission standards. We are also proposing that any
family that is not yet captured within the Tier 3 phase-in percentage
may remain on current certification fuel or, as discussed below,
California certification test fuel and test procedures through the 2019
MY. By the 2020 MY all evaporative and refueling emission
certifications would have to be on EPA test procedures and
certification fuels. It is useful to clarify that any confirmatory or
in-use testing for these families would be done on the fuel on which
they were originally certified. However, by the 2020 MY all vehicles
must be certified with Tier 3 certification test fuel and that test
fuel would have to be used in confirmatory and in-use testing.
    Finally, we are proposing that any vehicle certified to the
refueling spit back standard separately (mostly incomplete HDGVs) may
continue to do so using current certification fuel until the 2022 MY
even if it's evaporative and/or refueling emissions are certified on
Tier 3 certification fuel. This is reasonable since the fill quality of
the vehicle and eliminating spit back are not necessarily related to
the ethanol or sulfur content of the gasoline.
    There are two main fuel properties that influence evaporative
emissions: Ethanol content and vapor pressure. Current requirements
specify an emission test fuel with no ethanol for emissions testing;
however, the current regulation specifies that manufacturers must
perform service accumulation (durability) using fuel with, at a
minimum, the highest concentration of ethanol permissible under federal
law for in-use gasoline and that is commercially available in at least
one state. In this case, this provision has the effect of insuring that
manufacturers would design their fuel systems to account for the effect
of ethanol on permeation emissions. Even without ethanol in the test
fuel, the extended operation with gasoline-ethanol blends for service
accumulation would effectively force the manufacturers to design
systems which effectively control emissions from the blended fuel. By
regulation manufacturers must use a 10 percent ethanol fuel in current
evaporative emissions durability work. As a result, adding ethanol to
the test fuel for Tier 3 evaporative and refueling emission testing
should pose no new or greater challenge for manufacturers. A second
issue related to adding ethanol to the certification test fuel relates
to the emission measurement in the SHED. Emissions are detected by
flame ionization detectors (FID), which are less responsive to ethanol
than gasoline. This effect causes under-reporting from the ethanol
portion of the fuel vapor. Fuel-related emissions from the vehicle may
be slightly more weighted toward ethanol than gasoline, depending on
how the different fuel constituents permeate through various fuel-
system materials, how they evaporate from the bulk fuel in the tank at
varying temperatures, and how they adsorb onto and desorb from the
activated carbon in the canister. We are proposing to address this
issue by the use of a prescribed scaling factor. Under this approach
manufacturers would simply multiply their SHED measurement results by a
fixed value to adjust upward for the difference in the FID response to
ethanol. Data available to EPA suggest that a scaling value of
approximately 1.1 would be appropriate for E15.\294\ This means that
the value measured in the SHED would be multiplied by 1.10 to account
for a difference in the FID response. This was determined using data
which indicates that from a near worst case perspective the term within
the bracket { {time}  below equals 1.1.

    \294\ Moulis, C. (2012, January). SHED FID Responses for
Ethanol. Memorandum to the docket.
---------------------------------------------------------------------------

MHC adj = [(PBVn/T)-
(.000297)(ppmCfid)*{1 + ((1-ra)
(reth))/ 1 + ((reth)(ra)){time} ]

    This adjustment would apply to hot soak plus diurnal, refueling,
canister bleed, and spitback emission standards testing. For higher
ethanol blends (such as E85), the regulation already specifies
measurement and calculation procedures to adjust for this effect. We
are not proposing any changes to these procedures.
c. Vehicle Preconditioning for Nonfuel Hydrocarbon Emissions for the
Tier 3 Evaporative Emission Standards
    The proposed Tier 3 hot soak plus diurnal, leak, and canister bleed
emission standards taken together are expected to bring about the
widespread use of technology which effectively eliminates fuel vapor
emissions. The canister bleed and leak emission standards are not
influenced by non fuel hydrocarbon emissions from the vehicle. Nonfuel
hydrocarbon emissions from the vehicle are measured as part of SHED
emission testing, and are indistinguishable for fuel hydrocarbons when
a FID is used to measure the concentration. The level of these nonfuel
hydrocarbon emissions vary by vehicle and component design and
material. These emissions arise from paint, adhesives, plastics, fuel/
vapor lines, tires, and other rubber or polymer components and are
generally greater

with larger size vehicles. These nonfuel hydrocarbon emissions are
usually highest with newly manufactured vehicles and decrease
relatively quickly over time.
    Currently, manufacturers often conduct some preconditioning to
reduce or eliminate the effects of these nonfuel hydrocarbon emissions
on evaporative emissions measurements in the SHED. In the past, this
practice has not been addressed through regulatory provisions. However,
given the stringent level of the proposed Tier 3 hot soak plus diurnal
evaporative emission standards, and that nonfuel hydrocarbon emissions
are expected to be a significant portion of the hydrocarbon emissions
measured in the SHED, EPA believes that some sort of preconditioning
before certification testing is appropriate and that a regulatory
provision addressing this practice may be warranted. Providing some
recognition of and allowance for this practice would help to create the
proper balance between necessary and proper preconditioning to address
high nonfuel hydrocarbon emissions and excessive preconditioning which
could undermine the intent of the proposed hot soak plus diurnal
emission standard (~ 50 mg or less of fuel evaporative emissions). EPA
believes the goal of evaporative emissions preconditioning should be to
get nonfuel hydrocarbon emissions to what we call vehicle background
levels. A working definition of vehicle background level might be the
level which would occur naturally twelve months after production. A
provision in the regulations which addresses preconditioning reduces
ambiguity for the manufacturers and could reduce or eliminate any
uncertainty in the true meaning of certification test results.
    Manufacturer activity with regard to preconditioning often involves
two practices. First, manufacturers in some cases ``bake'' their test
vehicles at temperatures of 50 [deg]C or higher for periods of up to
ten or more days to accelerate the off-gassing of these nonfuel
hydrocarbon emissions before testing is conducted. While this practice
is common, there is no standardized method or protocol for this
preconditioning prior to new vehicle certification testing. For
example, some manufacturers bake for a set period of time in a climate
chamber while others bake in the climate chamber and periodically
measure nonfuel background in a SHED until an acceptable or stable
level of nonfuel hydrocarbon emissions is achieved. Second,
manufacturers often remove, modify, or clean certain components which
are the largest source of nonfuel hydrocarbon emissions.
Preconditioning could also include measures to eliminate minor fuel
drips, spills, or other fuel remnants which occur as a result of
vehicle preparation for testing.
    We are not proposing to specify standardized preconditioning
practices or protocols with regard to addressing nonfuel hydrocarbon
emissions before evaporative emission certification testing. However,
we are proposing general provisions in four areas. First, we would
specify in the regulations that preconditioning for the purpose of
addressing nonfuel hydrocarbon emissions is permitted. Second, we would
specify that any preconditioning is voluntary. Third, we would specify
that if preconditioning is conducted, the details must be specified to
EPA before certification testing, (i.e., at the time of the pre-
certification planning meeting). The goal of this preconditioning
should be to get nonfuel hydrocarbon emissions to what we would term
vehicle background levels as discussed above. The specifics to be
discussed with EPA could include details on vehicle baking practices
such the temperature and time duration in the climate chamber and
practices conducted as an alternative or complement to vehicle baking
such as installing used tires (drive and spare) on certification
vehicles, and allowing the windshield washer tank to be filled only
with water. In seeking to understand this issue, we ask for comment on
which components are the largest sources of these nonfuel hydrocarbons
and of these which are practical to modify or remove for the
evaporative emissions test.
    Fourth, as part of these considerations we would specifically
propose that no preconditioning be permitted for testing of any vehicle
aged more than twelve months from its date of manufacture. The only
exception we would consider is the use of an aged spare tire in lieu of
the spare tire on the test vehicle. For these vehicles, nonfuel
hydrocarbon emissions would presumably be reduced to a stable level due
to natural off gassing which begins after the vehicle is manufactured.
Emissions from any replacement parts or other vehicle maintenance would
presumably be encompassed within the margin below the standard created
by this natural off-gassing. EPA asks comment on how to address testing
of vehicles with relatively new drive tires and whether used drive
tires should be allowed in these circumstances. Data available to EPA
indicates that the background emission rate stabilizes to about two-
thirds of the level of the standard after about twelve months. These
levels are adequately below the proposed Tier 3 evaporative emission
standards so that nonfuel background would not unduly influence test
pass/fail outcomes and are within the range of values EPA expects to be
accommodated within the proposed evaporative emission standard. This
proposed restriction for vehicles older than 12 months would include
certification, confirmatory and in-use testing for any vehicle
certified to the proposed Tier 3 evaporative emission standards. We
request manufacturer data related to the change in nonfuel hydrocarbon
emission rates over time and on the best method to consider these
emissions as part of preconditioning before evaporative emission
testing.
d. Reciprocity With CARB
    Over the past 15 years EPA's ``enhanced evap'' test procedures have
been based on testing with 9 pound per square inch (psi) RVP gasoline
with test temperatures representing a summer day with peak temperatures
of about 96[emsp14][deg]F. CARB adopted the same basic procedures, but
specified that testing should occur with 7 psi RVP gasoline at
temperatures of up to 105[emsp14][deg]F. EPA and CARB agreed that
certification could be based on testing with either EPA or CARB
conditions and that these provided equivalent stringency for purposes
of evaporative control system design. However, the provision allowing
for this equivalence of test data preserved EPA's ability to also test
with either EPA or CARB temperature conditions. CARB always specified
EPA test conditions for refueling as they were deemed worst case. CARB
recently moved to change their certification test fuel to a 7 RVP
gasoline with 10 percent ethanol and as discussed in Section IV.D, we
are now proposing to change the Federal certification test fuel
specification to a 9 RVP gasoline with 15 percent ethanol.
    During the development of this proposal we carefully considered the
practice of CARB/EPA reciprocity with regard to certification test
fuels, hot soak plus diurnal test procedures, and emission test results