In previous determinations of CAA sec. 211(f), we looked broadly at
the use of the new fuel or fuel additive in all gasoline-powered
engines, vehicles, and equipment. This was appropriate at that time
because all gasoline-powered engines, vehicles and equipment were
certified using essentially the same fuel and were compatible with any
gasoline. Now, in light of the CAA sec. 211(f)(4) waivers, and the
changed certification fuel, E15 can be used in MY2001 and newer motor
vehicles but its use in other gasoline powered products has
demonstrated adverse effects on emissions and materials compatibility.
The legislative history of the 1977 CAA Amendments makes clear that the
purpose of CAA sec. 211(f) is to ensure that the introduction of new
fuels and fuel additives into commerce does not adversely impact
vehicle emissions.\118\
---------------------------------------------------------------------------

    \118\ See S. Rep. 95-127, (95th Cong., 1st Sess.), at 90 (``The
Administrator may waive the prohibition if the applicant establishes
that the additive will not impair the emission performance of
vehicles produced in model year 1975 and subsequent years.'').
---------------------------------------------------------------------------

    We retain certain aspects of previous interpretations. The first
E15 sec. 211(f)(4) waiver decision, in 2010, was the last occasion on
which we articulated our interpretation of CAA sec. 211(f), including
the relationship between the CAA sec. 211(f)(1) provision and the CAA
sec. 211(f)(4) waiver provision.\119\ We stated that the CAA sec.
211(f)(1) ``prohibition has evolved over time,'' but ``the concept of
applying this prohibition based on the relevant subset of vehicles
continues.'' \120\ For example, we explained that ``diesel fuel does
not need to be substantially similar to the fuel used in the
certification of gasoline vehicles, and E85 does not need to be
substantially similar to fuel used in the

certification of diesel vehicles.'' \121\ We also recognized that, in
approving a fuel as substantially similar, EPA could consider narrow as
well as broad subsets of motor vehicles when evaluating a fuel or fuel
additive for introduction into commerce under CAA sec. 211(f)(1).
---------------------------------------------------------------------------

    \119\ 75 FR 68145 (November 4, 2010).
    \120\ Id.
    \121\ Id.
---------------------------------------------------------------------------

    In assessing whether a fuel is substantially similar to a
certification fuel, we must look only to its use in the engines and
vehicles within which it can be used, and not its use in vehicles and
engines which are fueled by other types of fuel. Consistent with our
past interpretation, we again find that the use of the term ``any'' in
the prohibition (``any . . . vehicle or engine'') does not mean all
motor vehicles or 100 percent of the motor vehicle fleet.\122\ This is
supported by the plain meaning of the term ``any,'' which can mean
``one, some, or all indiscriminately of whatever quantity.'' \123\
---------------------------------------------------------------------------

    \122\ Id.
    \123\ Webster's Third New International Dictionary (1976); see
Green v. Biddle, 21 U.S. 1, 38 (1823) (``where the words of a law,
treaty, or contract, have a plain and obvious meaning, all
construction, in hostility with such meaning, is excluded'').
---------------------------------------------------------------------------

    As discussed further in Section <IP_ADDRESS> of the RTC, the use of the
phrase ``any fuel utilized in the certification of any model year 1975,
or subsequent model year, vehicle or engine'' clearly encompasses fuels
utilized in subsequent model years, such as Tier 3 E10 certification
fuel. In particular the reference to a certification fuel for a
``subsequent model year'' permits our comparison of E15 to Tier 3 E10
certification fuel, a fuel utilized in the certification of MY2020 and
later light-duty motor vehicles.
    For this CAA sec. 211(f)(1) sub sim interpretation we are faced for
the first time, however, with a situation where there are different
gasolines used in the certification of different gasoline vehicles and
equipment, and a different in-use gasoline (E15) that can only be used
in a subset of in-use vehicles and engines. Because of this, the
appropriate scope of review is all of the various vehicles and engines
within which gasoline can be used, and our assessment under sub sim
evaluates the appropriateness of fueling those vehicles and engines
with various gasoline-ethanol blends. In this unique circumstance, we
have the benefit of the CAA sec. 211(f)(4) waiver analyses that
supported partial grants of CAA sec. 211(f)(4) waivers for E15 in 2010
and 2011. These data provide technical information useful to informing
our sub sim analysis for E15. The use of data collected or analyzed in
the context of a CAA sec. 211(f)(4) to inform a sub sim determination
under CAA sec. 211(f)(1) is consistent with our prior practice. For
example, in making the sub sim determination in our 1991 sub sim
interpretive rule, we considered evidence that supported the CAA sec.
211(f)(4) waivers granted to methanol.\124\ Based on the data in those
waiver analyses, as well as additional data gathered in the eight years
since that waiver, we have assessed whether E15 is sub sim to the Tier
3 E10 certification fuel for use in all of the vehicles and engines
that could be exposed to fueling on E15 in-use.
---------------------------------------------------------------------------

    \124\ 56 FR 5352, 5353 (February 11, 1991). We explained that
``although methanol is not included in the group of aliphatic
alcohols and ethers covered by today's [sub sim interpretive rule]
revision, the evidence in these fuel waiver dockets involving
methanol supports the conclusion that unleaded gasolines containing
aliphatic ethers and/or alcohols (excluding methanol), at up to 2.7
percent oxygen by weight, are substantially similar to unleaded
gasoline used in light-duty vehicle emissions certification.'' Id.
---------------------------------------------------------------------------

    In this action, we are also extending our assessment beyond those
vehicles and engines certified under CAA sec. 206. We are again in a
unique circumstance where due to our analysis under the CAA sec.
211(f)(4) waiver (which covers all motor vehicles, motor vehicle
engines, nonroad engines, and nonroad vehicles), we have knowledge of
the use of E15 in particular vehicles and engines causing or
contributing to emission systems failures.\125\ Because we have the
benefit of this information, we find it appropriate to assess under
211(f)(1) whether E15 is sub sim to E10 when used in those vehicles and
engines. Some of these vehicles and engines are certified under CAA
sec. 213(a).\126\ Therefore, we are also looking at whether E15 is sub
sim to Tier 3 E10 certification fuel when used in nonroad products
certified under CAA sec. 213(a).
---------------------------------------------------------------------------

    \125\ See 75 FR 68144 (November 4, 2010).
    \126\ CAA sec. 213(a)
---------------------------------------------------------------------------

    In the proposal, we suggested that the comparison was relatively
narrow--comparing the use of E15 to the use of Tier 3 E10 certification
fuel in Tier 3 vehicles alone; i.e., the fuel utilized in the
certification of that vehicle or engine. We received many comments
suggesting this is not an appropriate assessment under CAA sec.
211(f)(1) and we are not taking this approach in this action. Instead,
we have concluded that it is appropriate to broaden our analysis to
consider the use of E15 in all vehicles and engines that could be
exposed to fueling on E15 in-use to determine whether E15 is
substantially similar to Tier 3 E10 certification fuel.
    Many commenters suggested that CAA sec. 211(f)(1) should be
protective of all vehicles and engines in the fleet. We agree, and this
action protects vehicles and engines by finding that the use of E15 in
any MY2000 or older light-duty gasoline motor vehicle, any heavy-duty
gasoline motor vehicle or engine, any highway or off-highway
motorcycle, or any gasoline-powered nonroad engines, vehicles or
equipment is not sub sim to Tier 3 E10 certification fuel. We also
maintain the prohibition on use in these vehicles, engines and
equipment implemented in the MMR.\127\ These actions are being taken to
protect the vehicles and engines for which use of E15 would be harmful.
---------------------------------------------------------------------------

    \127\ 40 CFR 80.1504(a)(1).
---------------------------------------------------------------------------

    In past sub sim interpretative rules, we have provided physical and
chemical characteristics of fuels and fuel additives that would be
considered sub sim to certification fuel. These interpretative rules
broadly applied to a variety of fuel and fuel additives. Then, at
registration, fuel and fuel additive manufacturers must demonstrate
whether their fuel or fuel additive is sub sim or has a CAA sec.
211(f)(4) waiver from being sub sim.
    In this interpretative rule we are taking both steps for E15 as
compared to tier 3 E10 certification fuel--interpreting what is
``substantially similar'' to tier 3 E10 certification fuel, and
providing a narrow definition for gasoline-ethanol blends containing
greater than ten and less than 15 percent ethanol, and fuel additives
utilized in that fuel that is sub sim to tier 3 E10 certification fuel
and determining that E15, as a fuel, is sub sim. We are putting forth
our determination that E15 meeting certain criteria is sub sim when
used in MY2001 and newer light-duty vehicles.
4. Criteria for Determining Whether a Fuel Is ``Substantially Similar''
    In this action, we are considering whether E15 is sub sim to Tier 3
E10 certification fuel when used in all motor vehicles and motor
vehicle engines certified under CAA sec. 206 and nonroad products
certified under CAA sec. 213(a).
    As discussed in Section II.A.4, CAA sec. 211(f)(1) prohibits fuel
and fuel additive manufacturers from introducing into commerce fuel or
fuel additives that are not substantially similar to fuel or fuel
additives utilized in the certification of motor vehicles. CAA sec.
211(f)(4) provides a waiver from this prohibition for fuels and fuel
additives that can be established that such fuel or fuel additive, or a
specified

concentration thereof, will not cause or contribute to a failure of any
emission control device or system (over the useful life of the motor
vehicle, motor vehicle engine, nonroad engine, or nonroad vehicle in
which such device or system is used) to achieve compliance by the
vehicle or engine with the emission standards to which it has been
certified pursuant to CAA sec. 206 and 213(a).
    To make this assessment, we have generally considered the effects
of a fuel or fuel additive on emissions (exhaust and evaporative),
materials compatibility, and driveability for motor vehicles and motor
vehicle engines certified under CAA sec. 206.\128\
---------------------------------------------------------------------------

    \128\ See, e.g., 56 FR 5354 (February 11, 1991).
---------------------------------------------------------------------------

    The criteria we consider when determining whether a fuel or fuel
additive is sub sim to certification fuel under CAA sec. 211(f)(1) are
similar to those criteria we consider when determining whether a new
fuel or fuel additive should receive a waiver to CAA sec. 211(f)(1)
under CAA sec. 211(f)(4). When determining whether a fuel or fuel
additive is sub sim to certification fuel under CAA sec 211(f)(1), we
have interpreted the criteria of emissions, materials compatibility,
and driveability as necessary to ensure that any fuel or fuel additive
determined to be sub sim will not impair the emission controls of
vehicles, engines, and equipment, as intended by Congress. While the
areas for consideration under CAA sec. 211(f)(1) and sec. 211(f)(4) are
similar, the requirements in each provision differ. CAA sec. 211(f)(1)
only requires that fuels be sub sim to certification fuel, while CAA
sec. 211(f)(4) requires that the new fuel or fuel additive will not
cause or contribute to any vehicles or engines exceeding their
emissions standards over the fuel useful life of the vehicles or
engines.
    In practice, EPA has implemented CAA secs. 211(f)(1) and 211(f)(4)
by evaluating similar criteria when defining which fuels are sub sim
and when evaluating 211(f)(4) waiver requests (i.e., emissions,
materials compatibility, and driveability).\129\ This is because these
three areas speak both to whether a fuel or fuel additive is sub sim to
certification fuel and whether such a fuel will damage a vehicle or
engine's emission controls. We consider these criteria to be
intrinsically linked as they are intended to answer the same question:
Whether a fuels or fuel additive will harm emissions controls on
vehicles and engines or result in increases in regulated emissions.
---------------------------------------------------------------------------

    \129\ See 75 FR 68144-68145 (November 4, 2010).
---------------------------------------------------------------------------

    Furthermore, we believe that any new fuel or fuel additive that
would cause or contribute to vehicles and engines exceeding emissions
standards is, by definition, not substantially similar to certification
fuel under sub sim. Given the intent of CAA sec. 211(f)(1) to protect
emission controls, it would be inappropriate to define sub sim in a
manner that included fuels or fuel additives that caused or contributed
to vehicles exceeding their emissions standards. As a result, we have
in the past interpreted sub sim conservatively to help ensure that this
situation did not arise. We continue to believe that this is
appropriate to ensure that CAA sec. 211(f)(1) protects the emission
controls of vehicles and engines certified under CAA secs. 206 and 213.
We also believe the converse is true for newer light-duty motor
vehicles (i.e., MY2001 and newer). In older vehicles, especially MY2000
and older motor vehicles, where certified emission standards were
relatively less stringent than more modern standards (i.e., National
Low Emission Vehicle (NLEV), Tier 2, and Tier 3 vehicle emission
standards), there was a substantial amount of headroom (i.e., the
amount between the actual level at which a vehicle is certified and the
standard that the vehicle is subject to, typically around 50 percent of
the standard,\130\ which allowed for fuels or fuel additives to
significantly increase emissions in absolute terms without causing
vehicles to exceed emission standards. In modern vehicles, with more
stringent emissions standards, it is almost impossible to have large,
absolute increases in emissions and have a vehicle or engine meet its
emissions standards. Even small absolute changes in emissions can cause
vehicles to exceed emission standards. We believe that when a relative
increase in the emissions profile of a new fuel or fuel additive
compared to a certification fuel is sufficient to result in vehicles
and engines exceeding certified emissions standards in use, the new
fuel or fuel additive is not substantially similar to the certification
fuel since there is very little room in standards for small absolute
changes. Thus, while our analysis accompanying the E15 partial waivers
considered whether E15 caused or contributed to vehicles and engines
exceeding emissions standards over the full useful lives of the
vehicles, we believe that the same analysis can inform our
determination and in what circumstances E15 is sub sim to Tier 3 E10
certification fuel.
---------------------------------------------------------------------------

    \130\ See 75 FR 68111 (November 4, 2010).
---------------------------------------------------------------------------

    In order to determine whether E15 is sub sim to Tier 3 E10
certification fuel, we must consider the effects that E15 would have on
all vehicles, engines, and equipment relative to Tier 3 E10
certification fuel. For each class of vehicles, engines, and equipment,
we need to evaluate E15's relative effect on emissions, materials
compatibility, and driveability. For the most part, we have already
considered the effects of E15 on all vehicles, engines, and equipment
certified under CAA secs. 206 and 213 in the E15 partial waivers and
the MMR. In those actions, we evaluated the effect of E15 use on
emissions (exhaust and evaporative), materials compatibility, and
driveability over the full useful lives of MY2000 and older motor
vehicles, MY2001 and newer light-duty motor vehicles, nonroad products
(including motorcycles and marine engines), and heavy-duty gasoline-
fueled vehicles. While the focus of the analysis for the E15 waiver
decisions was on E15 relative to indolene (i.e., E0) and this sub sim
determination is on E15 relative to E10, we generally anticipate that
there would be less differences when E15 is compared to E10 in the
national vehicle and engine fleet. A summary of our finding for these
classes of vehicles and engines is presented below, but the full
discussion and all data and literature used to support our findings is
contained in the E15 waivers and the MMR and are incorporated here by
reference and included in the docket. Although we incorporate the
discussion and all data and literature in support of the E15 partial
waivers, we are not reopening those waivers with this action. We
separately discuss in sections II.C.6-8 the following vehicles and
classes:

 MY2000 and older motor vehicles
 MY2001 through 2019 light-duty motor vehicles
 MY2020 and newer light-duty motor vehicles (i.e., Tier 3
vehicles)
 Vehicles, engines, and equipment prohibited from E15 use

    Since Tier 3 certified vehicles did not exist at the time of the
E15 waivers and the MMR, we consider those vehicles separately from the
MY2001-2019 light-duty vehicles. As described in Section II.C.9, it is
appropriate for us to restrict the applicability of this new definition
of sub sim to only those vehicles, engines, and equipment for which we
are determining that E15 is sub sim to Tier 3 certification fuel.
5. Impact of Volatility on ``Substantially Similar''
    In determining whether a fuel is substantially similar, our
analysis compares a fuel (in this case, E15) to a fuel utilized in the
certification of motor vehicles (in this case, Tier 3 E10 certification
fuel). Our certification fuel

regulations specify a volatility limit for Tier 3 E10 certification
fuel of 9.0 psi.\131\ In this action, we are also considering our sub
sim interpretation, in the context of our interpretation of CAA sec.
211(h)(4) described above.
---------------------------------------------------------------------------

    \131\ See 79 FR 23414, 23526 (April 28, 2014). See also 40 CFR
1065.710.
---------------------------------------------------------------------------

    EPA proposed two alternative analyses for a sub sim interpretation
for E15. The first analysis compared E15 at 10.0 psi--i.e., after
application of the CAA sec. 211(h)(4) waiver--to E10 certification fuel
at 9.0 psi RVP. The second analysis compared E15 at 9.0 psi RVP to E10
certification fuel at 9.0 psi RVP. For the reasons explained below, we
have adopted the latter interpretation in this final action--comparing
E15 at 9.0 psi RVP to E10 certification fuel at 9.0 psi RVP. As stated
in Section II.A.1, CAA sec. 211(f) exists to protect the emissions
control systems of vehicles and engines and thus prevent the
degradation of those systems. The emissions control systems of vehicles
and engines have become increasingly sensitive to changes in volatility
as emissions standards have become increasingly stringent over time.
Therefore, changes in volatility can also affect the efficacy of
evaporative emissions systems. It would be inappropriate to completely
ignore the volatility of a fuel in evaluating whether it is sub sim,
especially as volatility relates to evaporative emissions. We continue
to believe that the volatility of fuel is important to consider when
determining whether a fuel or fuel additive is substantially similar to
fuel utilized in the certification of vehicles and engines under CAA
sec. 211(f)(1). In particular, the volatility of fuels can have a
significant impact on the evaporative emissions (as well as exhaust
emissions) from a vehicle, one of the considerations EPA has analyzed
under sub sim historically and in this action, as described in this
section.
    In the proposal, we suggested that it may be appropriate to utilize
our previous approach to volatility in a sub sim determination. In
previous sub sim interpretative rules and corresponding definitions, we
have required gasoline to only meet the volatility requirement of a
single volatility class defined in ASTM Standard D4814-88, which range
from 7.0 psi to 15.0 psi over the course of the year. We viewed this as
appropriate when considering fuels and fuel additives that themselves
are not impacting the volatility of gasoline during the summer months.
When volatility impacts do not impair evaporative emissions controls
that are important to air quality, we only need to consider the
volatility impacts of the fuel or fuel additive to ensure that the fuel
still falls within the bounds of what is considered to be gasoline.
Therefore, we do not find it would be appropriate to compare E15 at
10.0 psi to E10 at 9.0 psi.
    In this action, we are providing a new interpretation of CAA sec.
211(h)(4) that applies the 1-psi waiver to ethanol blends greater than
10 but no more than 15 volume percent ethanol. There, Congress provided
a 1-psi waiver for the blending of gasoline-ethanol blends in order to
promote ethanol blending in gasoline and ensure that those gasoline-
ethanol blends could remain in use. CAA sec. 211(h)(4) does not provide
any additional analysis or consideration for EPA prior to the
application of the 1-psi waiver, nor does it provide guidance to EPA on
the operability of the statutory provisions. E15 will be treated
similarly to E10 under CAA secs. 211(f)(1) and 211(h)(4); blendstocks
produced by fuel and fuel additive manufacturers typically meet a
lower-RVP standard, and then, upon addition of ethanol by downstream
parties, the blended fuel is given an RVP allowance, allowing up to 1.0
psi higher RVP. The approach we are taking gives meaning to both
211(f)(1) and its consideration of volatility in determining whether a
fuel is sub sim, and 211(h)(4) which provides the 1-psi waiver.
Therefore, the 1-psi waiver operates after other limitations on the
introduction of E15 into commerce.
    Therefore, the analysis under CAA sec. 211(f) is limited in scope
in this particular situation. We need not address the 1-psi waiver that
is expressly provided in another provision of CAA sec. 211 by analyzing
emission impacts at the volatility level provided through the waiver in
order to determine whether a fuel is substantially similar to a
certification fuel. In this case, we need not look at the emissions
impacts of E15 at 10.0 psi RVP because CAA sec. 211(h)(4), as
interpreted in this action, will itself allow for the 1-psi waiver for
E15. It is not the case that volatility is wholly irrelevant to our
evaluation of what is sub sim, given that the level of RVP for gasoline
certification fuel used to certify motor vehicles is 9.0 psi, but
rather in this case, we find it would be inappropriate to limit under
sub sim the volatility of a fuel that Congress allowed a 1-psi waiver
from the volatility standard, under CAA sec. 211(h)(4). Our
determination under sec. 211(f)(1) only allows E15 to be introduced
into commerce without a CAA sec. 211(f)(4) waiver.\132\ It is the
operation of CAA sec. 211(h)(4) that allows E15 to receive the 1-psi
waiver, resulting in E15 having to meet a 10.0 psi RVP limit, rather
than a 9.0 psi RVP limit.
---------------------------------------------------------------------------

    \132\ E10 was granted a waiver under CAA sec. 211(f)(4) without
any conditions, in contrast to other CAA sec. 211(f)(4) waivers,
which included, for example, conditions on fuel characteristics such
as RVP.
---------------------------------------------------------------------------

    It follows that our point of comparison is E15 at 9.0 psi to Tier 3
E10 certification fuel (i.e., E10 at 9.0 psi). Additionally, our
finding in this action that E15 is substantially similar to Tier 3 E10
certification fuel when used in MY2001 and newer light-duty motor
vehicles is limited to E15 at 9.0 psi. In considering whether E15 is
sub sim to tier 3 E10 certification fuel in the areas of materials
compatibility, emissions, and driveability, we have done so comparing
E15 at 9.0 psi to Tier 3 E10 certification fuel at 9.0 psi. This
approach recognizes the importance of volatility on evaporative
emissions, one of the criteria we have historically considered in
evaluating whether a fuel is sub sim.
6. Technical Rationale and Discussion for Tier 3 Vehicles (MY2020 and
Newer)
    As discussed above, we have considered whether a fuel has similar
effects on emissions, materials compatibility, and driveability when
defining what fuels are substantially similar to certification fuel.
Based on existing data and our engineering judgement, we have concluded
that E15 at 9.0 psi RVP, with its additional oxygen content, would have
effects on emissions, materials compatibility, and drivability
substantially similar to Tier 3 E10 certification fuel (also at 9.0 psi
RVP) in Tier 3 vehicles. While test data is still limited on Tier 3
vehicles, we have been able to draw upon test data and information on
prior year motor vehicles (primarily NLEV and Tier 2 certified vehicles
representative of MY2001 and newer light-duty motor vehicles) to
support this conclusion as the impacts on Tier 3 motor vehicles are
expected to be of a similar or lesser concern than on prior year motor
vehicles.
a. Exhaust Emissions
    In the 2010 and 2011 CAA sec. 211(f)(4) partial waivers for E15, we
concluded from available data that neither the immediate combustion
effects nor the long-term durability impacts of operating on E15 would
prevent MY2001 and newer light-duty motor vehicles from complying with
their full useful life emission

standards.\133\ This decision was supported by a large study conducted
by DOE that tested 27 high-sales vehicles spanning model years 2000 to
2007 \134\ using ethanol splash blends made from Tier 2 certification
gasoline (E0).\135\ Analysis of the resulting data shows that E15
produced approximately 5 percent higher nitrogen oxides
(NOX), 4 percent higher non-methane organic gases (NMOG),
and 4 percent lower CO compared to E10, though none of these
differences was statistically significant. This work did not measure
particulate matter (PM) emissions, but the expectation at the time was
that PM should react to ethanol in a similar way as NMOG emissions.
---------------------------------------------------------------------------

    \133\ See 75 FR 68096 (November 4, 2010).
    \134\ This study was designed to evaluate the long-term exhaust
emissions effects of E15 on NLEV and Tier 2 light-duty vehicles.
    \135\ Knoll, K., West, B., Huff, S., Thomas, J. et al.,
``Effects of Mid-Level Ethanol Blends on Conventional Vehicle
Emissions,'' SAE Technical Paper 2009-01-2723, 2009. This preamble
refers to this study as ``the DOE study''.
---------------------------------------------------------------------------

    Since the time of the 2010 and 2011 waiver decisions, additional
data have been published on the effects of gasoline-ethanol blends on
Tier 2 vehicles.\136\ The EPAct/V2/E-89 study (referred to as the
``EPAct study''), jointly conducted by EPA, DOE/National Renewable
Energy Laboratory (NREL), and the Coordinating Research Council (CRC)
in 2009 to 2010, looked at the short-term effects of five fuel
properties, including ethanol concentration, on emissions from 15 high-
sales light-duty vehicles from MY2008. Measurements included gaseous
pollutants, and PM, a pollutant whose relationship to fuel properties
had previously not been examined in much detail for gasoline vehicles.
The size and scope of this study allowed for statistical models to be
developed that could be used to correlate the impacts of the five fuel
properties, including ethanol concentration, on emissions, enabling
projections to be made of the emission impacts of a wide range of
fuels, not limited to those tested. Results generally confirmed the
NOX and CO emission impacts described above from the
addition of ethanol to gasoline, while indicating that the effects on
NMOG and PM are more complex and depend on other fuel parameters, such
as the fuel's distillation profile and aromatics content.\137\ \138\
For example, comparing E15 and E10 fuels in the DOE study, the EPAct
statistical models estimate approximately 2 percent higher
NOX, 4 percent lower NMOG, 2 percent lower CO, and 2 percent
higher PM for E15. If we instead assume E10 market fuel as a starting
point, the EPAct models project splash blending to E15 will produce 2
percent higher NOX, 2 percent higher NMOG, 2 percent lower
CO, and 4 percent higher PM.\139\
---------------------------------------------------------------------------

    \136\ Tier 2 vehicles generally include light-duty motor
vehicles produced between MY2007-2019. Some manufacturers began
making Tier 2 vehicles as early as MY2004 and some can continue to
do so as late as MY2021.
    \137\ EPA Office of Transportation and Air Quality. ``EPAct/V2/
E-89: Assessing the Effect of Five Gasoline Properties on Exhaust
Emissions from Light-Duty Vehicles Certified to Tier 2 Standards:
Final Report on Program Design and Data Collection''. EPA-420-R-13-
004. April 2013. The preamble refers to this as ``the EPAct Study''.
    \138\ Butler, A., Sobotowski, R., Hoffman, G., and Machiele, P.,
``Influence of Fuel PM Index and Ethanol Content on Particulate
Emissions from Light-Duty Gasoline Vehicles,'' SAE Technical Paper
2015-01-1072, 2015, doi:10.4271/2015-01-1072.
    \139\ Since these figures represent the output of multivariate
models whose coefficients survived a process of statistical testing,
they are interpreted as meaningful despite being small.
---------------------------------------------------------------------------

    Another observation from this study was that the sensitivity of
emissions to ethanol blending varied significantly across the test
vehicles. Because the EPAct test fleet was designed to include a range
of high-sales vehicles, it is reasonable to expect the average effect
across the test vehicles to be representative of the in-use fleet of
Tier 2 vehicles with port-fuel-injection.
    Two studies (projects E-94-2 and E-94-3) published by CRC in 2017
and 2018, respectively, examined the effects of ethanol and PM Index on
PM and other emissions from MY2012 to2015 Tier 2 vehicles, all with
gasoline direct injection (GDI) engines and several with
turbocharging.\140\ \141\ The E-94-2 study used a parametric design,
meaning one fuel property was changed at a time while holding others
constant; so for example, test fuels differing in ethanol content were
matched in PM Index, T50, RVP, and several other properties.\142\
Results for the overall test fleet of 16 vehicles in E-94-2 showed no
statistically significant effect of E10 relative to E0 for total
hydrocarbons (THC), NOX, or CO, while PM increased by 19
percent for the regular-grade (87 anti-knock index or AKI) test fuels.
The E-94-3 study tested a four-vehicle subset on four E10 splash blends
made from the E0 fuels in E-94-2, and found a PM increase of 21% on
average, consistent with the effect found in the larger E94-2 study.
Assuming this PM effect is linear over small fuel changes, we would
expect around 10 percent higher PM when moving from E10 to E15.
Comparing these results to the EPAct study and DOE study above suggests
that later-technology vehicles with direct injection (though still
certified to Tier 2 emission standards) have equal or lower sensitivity
to ethanol for gaseous emissions, but may be more sensitive for PM.
---------------------------------------------------------------------------

    \140\ Morgan, Peter; Smith, Ian; Premnath, Vinay; Kroll,
Svitlana; Crawford, Robert. ``Evaluation and Investigation of Fuel
Effects on Gaseous and Particulate Emissions on SIDI In-Use
Vehicles''. SwRI 03.20955. Southwest Research Institute, San
Antonio, TX. CRC E-94-2. Coordinating Research Council, Alpharetta,
GA. March 2017.
    \141\ Morgan, Peter; Lobato, Peter; Premnath, Vinay; Kroll,
Svitlana; Brunner, Kevin; Crawford, Robert. ``Impacts of Splash-
Blending on Particulate Emissions for SIDI Engines''. SwRI 03.20955-
1. Southwest Research Institute, San Antonio, TX. CRC E-94-3.
Coordinating Research Council, Alpharetta, GA. June 2018.
    \142\ This parametric study design is referred to as ``match
blending'', where the hydrocarbon components of each test fuel are
adjusted so that specific properties, such as octane, RVP, and/or
aromatics content, are matched across different ethanol levels in
the final blends. This is in contrast to ``splash blending'', where
no effort is made to control fuel properties as ethanol is added,
making it impossible to ascertain whether observed impacts are due
to the presence of ethanol or the other resulting changes in the
fuel.
---------------------------------------------------------------------------

    Another study published in 2018 by the University of California,
Riverside Center for Environmental Research and Technology (CE-CERT)
looked at the effects of ethanol and aromatics on emissions from five
vehicles, model years 2016 or 2017, all with GDI engines and certified
to Tier 3 and/or LEV III standards.\143\ While this provides a useful
look at recent-model technology impacts, it should be noted that,
because this study only employed five test vehicles, we are less
certain how well this study's average effects represent this technology
type in the in-use fleet. The test fuels included E0, E10, and E15 that
were closely aligned on aromatic content (at two levels, 21 percent and
29 percent by volume) but the mid-point distillation temperature (T40-
T50) was uncontrolled, and declined significantly as the ethanol
content increased.\144\ Results of this study showed no statistically
significant difference in NOX, non-methane hydrocarbons
(NMHC), or PM when comparing E15 to E10 at either aromatics level.
While not statistically significant, a trend of increasing PM with an
increase in ethanol content was observed at the higher aromatics level,
suggestive of a reinforcing interaction between ethanol and aromatics
that has been described in other published work. At the lower aromatics
level, the trend

suggests PM increase from E0 to E10 and then decrease from E10 to E15.
---------------------------------------------------------------------------

    \143\ Karavalakis, G; Durbin, T; Yang, J; Roth, P., ``Impacts of
Aromatics and Ethanol Content on Exhaust Emissions from Gasoline
Direct Injection (GDI) Vehicles''. University of California, CE-
CERT, April 2018.
    \144\ The EPAct study found T50 to have a meaningful and
statistically significant impact on NMOG, NMHC, NOX, and
PM emissions. Consequently, the results of this study are likely
confounded by changes in mid-point distillation, making it difficult
to ascertain statistically significant impacts of the ethanol
content changes and limiting the usefulness of the study.
---------------------------------------------------------------------------

    While there are limited data on Tier 3 vehicles, the results of the
Tier 2 and Tier 3 vehicle studies cited above are nevertheless largely
consistent with each other given that ethanol blending affects many
other fuel properties, given that ethanol is blended into gasoline in
various ways that affect the collateral property changes differently,
and given the varying impacts from vehicle to vehicle. This makes it
difficult to interpret trends across the body of literature without
detailed information on multiple fuel properties. However, since the
early 1990s, a number of programs have studied the effects of ethanol
on emissions from earlier vintage vehicles, and based on these studies,
emissions models have been published, including the Complex Model,\145\
Predictive Model,\146\ and MOVES simulator,\147\ and the results from
the more recent studies are also largely consistent with them given the
vehicle to vehicle differences, uncontrolled variables, and statistical
uncertainty. Namely, ethanol blending causes slight increases in
NOX emissions and slight decreases for CO emissions.
---------------------------------------------------------------------------

    \145\ See ``Complex Model Used to Analyze RFG and Anti-dumping
Emissions Performance Standards,'' available at https://www.epa.gov/fuels-registration-reporting-and-compliance-help/complex-model-used-analyze-rfg-and-anti-dumping.
    \146\ See ``California Gasoline Predictive Models, and CARBOB
Model Development,'' available at https://www.arb.ca.gov/fuels/gasoline/premodel/pmdevelop.htm.
    \147\ See ``Moves and Other Mobile Source Emissions Models,''
available at: https://www.epa.gov/moves.
---------------------------------------------------------------------------

    Earlier studies did not evaluate PM emission impacts from ethanol
blending, so we are limited to consideration of only the more recent
studies. The CRC E-94-3 and CE-CERT studies both tested ethanol splash
blends in recent model year GDI vehicles, and one found an increase in
PM with incremental ethanol (E0 to E10) while the other showed no
significant impact (E10 to E15). Neither study controlled T50 between
ethanol levels, but a notable difference between them was the range of
T50 levels in the test fuels. The E10 test fuel in the CE-CERT study
had lower T50 levels and additional ethanol blending depressed T50
significantly, more consistent with what we would expect in a median
market fuel moving to E15, versus the higher T50s in the CRC study
where E10 was the upper blend limit.148 149 Applying the
findings of the EPAct study to the CE-CERT study suggests that the PM
reduction from declining T50 in the low-aromatic CE-CERT E15 would have
offset a small PM increase caused by ethanol's hindrance of droplet
evaporation, as described elsewhere in the
literature.150 151 In the case of the high-aromatics fuels
in that study, the PM trend suggests this T50 benefit was not
sufficient to fully overcome the droplet cooling effect. As a general
conclusion, it seems reasonable to accept the CE-CERT study conclusion
that moving from E10 to E15 in a T50, aromatics, and PM Index space
representative of typical market fuels is not expected to produce a
significant increase in tailpipe PM emissions from Tier 2 and 3
vehicles.
---------------------------------------------------------------------------

    \148\ ``Fuel Trends Report: Gasoline 2006-2016.'' US EPA Office
of Transportation and Air Quality, Washington, DC. EPA420-R-17-005.
October, 2017. See Section 6.C.f. on E200 data, which can be
converted to T50.
    \149\ ``Determination of the Potential Property Ranges of Mid-
Level Ethanol Blends.'' American Petroleum Institute, Washington,
DC. April 2010. See Figure 7.
    \150\ Butler, A., Sobotowski, R., Hoffman, G., and Machiele, P.,
``Influence of Fuel PM Index and Ethanol Content on Particulate
Emissions from Light-Duty Gasoline Vehicles,'' SAE Technical Paper
2015-01-1072, 2015.
    \151\ Burke, S., Rhoads, R., Ratcliff, M., McCormick, R. et al.,
``Measured and Predicted Vapor Liquid Equilibrium of Ethanol-
Gasoline Fuels with Insight on the Influence of Azeotrope
Interactions on Aromatic Species Enrichment and Particulate Matter
Formation in Spark Ignition Engines,'' SAE Technical Paper 2018-01-
0361, 2018.
---------------------------------------------------------------------------

    While some criteria pollutants would have relative increases
(NOX) and others have similar decreases (VOC and CO) while
still others are less certain (PM) on E15 compared to E10, these
changes are all relatively small. In the E15 CAA sec. 211(f)(4) partial
waivers, we determined that effects of this magnitude were too small to
cause or contribute to MY2001 and newer light-duty motor vehicles to
exceed the vehicles' certified exhaust emissions standards and we
expect that this would also be the case for Tier 3 vehicles. To put
this into context, Table II.C-1 shows gram-per-mile exhaust emission
standards (limits) for FTP-cycle certification of new light-duty motor
vehicles under recent Federal regulatory programs. Vehicle
manufacturers typically try to calibrate their products to have
compliance margins of on the order of 50 percent when new to ensure
they will meet emission requirements over their full useful lives,
meaning their actual emission level is often about half the standard.
The Tier 3 standards are still being phased in, but we expect
compliance margins may be somewhat smaller as the lower emission levels
such as Tier 3 Bin 30 are more challenging to meet. In any case, these
margins are significantly larger than even the 10 percent PM effect
estimated from the CRC E-94-3 study.

                Table II.C-1--FTP-Cycle Exhaust Emission Standards for Recent Light-Duty Programs
----------------------------------------------------------------------------------------------------------------
             Certification level/bin                NOX (g/mi)      NMOG (g/mi)      CO (g/mi)      PM (mg/mi)
----------------------------------------------------------------------------------------------------------------
NLEV/TLEV.......................................             0.4           0.125             3.4  ..............
Tier 2/Bin 5....................................            0.05           0.075             3.4              10
                                                 --------------------------------
Tier 3/Bin 30...................................         0.030 NMOG + NOX                    3.4               3
----------------------------------------------------------------------------------------------------------------

    While CAA sec. 211(f)(1) does not define the magnitude of
acceptable emission impacts or other specific criteria for how to
determine whether a fuel or fuel additive is substantially similar to
certification fuel, we believe that the small changes in exhaust
emissions compared to the certification levels for E15 relative to Tier
3 E10 certification fuel used in Tier 3 vehicles can be considered to
be within the scope of what we have determined to be sub sim in our
prior sub sim interpretive rulemakings. For example, if a Tier 3
vehicle were certified on E10 fuel with PM emissions of 2.0 mg/mi (33%
compliance margin), a 10% PM increase due to fueling the vehicle with
E15 would increase its PM emissions to 2.2 mg/mi. This is still
significantly below its 3 mg/mi compliance limit (26% compliance
margin).
    Therefore, we believe that E15 is sub sim to Tier 3 E10
certification fuel from the perspective of exhaust emissions for Tier 3
light-duty motor vehicles.

b. Evaporative Emissions
    EPA has set evaporative emission standards for motor vehicles since
1971. During the ensuing years, these evaporative standards have
continued to evolve, resulting in additional evaporative emissions
reductions. Consideration of whether E15 is substantially similar to
Tier 3 E10 certification fuel for evaporative emissions requires
consideration of the applicable evaporative emissions standards to
which the particular motor vehicles were certified, in this case Tier 3
motor vehicles. There are now six main components to motor vehicle
evaporative emissions that are important for our standards: (1) Diurnal
(evaporative emissions that come off the fuel system as a motor vehicle
heats up during the course of the day); (2) refueling emissions
(evaporative emissions that come off the fuel system as the vehicle is
refueled); (3) hot soak (evaporative emissions that come off a hot
motor vehicle as it cools down after the engine is shut off); (4)
running loss (evaporative emissions that come off the fuel system
during motor vehicle operation); (5) permeation (evaporative emissions
that come through the walls of elastomers in the fuel system and are
measured as part of the diurnal test); and (6) unintended leaks due to
deterioration/damage that is now largely monitored through onboard
diagnostic systems.
    For hot soak, permeation, and unintended leak evaporative
emissions, we expect that E15 would have a similar effect as Tier 3 E10
certification fuel. In the E15 partial waivers, we stated that we did
not expect that E15 would have an effect on hot soak, permeation, and
unintended leak evaporative emissions based on a review of the data and
on the fact that auto manufacturers have been required to age vehicles
on E10 for evaporative emissions durability testing since MY2004. We
are not aware of any information suggesting that Tier 3 vehicles would
behave differently since they are aged for evaporative emissions
durability on E15 and certified on Tier 3 E10 certification fuel.
Furthermore, in our review of the testing of permeation on pre-Tier 3
vehicles (i.e., prior to changes made to address permeation) in the E15
partial waiver decisions, while ethanol was shown to significantly
worsen permeation emissions, the effect appears to be fully reached at
E10, as there was no discernable worsening of the impacts at higher
ethanol concentrations.\152\ Vehicle manufacturers have now redesigned
their fuel systems to control permeation on E10 sufficiently to meet
the Tier 3 evaporative emission standards. Consequently, we do not
anticipate permeation emissions with E15 to be any higher than with
E10.
---------------------------------------------------------------------------

    \152\ See 75 FR 68115-68120 (November 4, 2010) and 76 FR 4675-
4681 (January 26, 2011).
---------------------------------------------------------------------------

    Refueling, diurnal, and running loss evaporative emissions are
mostly a function of volatility of the fuel. As discussed in Section
II.C.4, to determine whether a fuel is sub sim to Tier 3 E10
certification fuel, it is necessary to evaluate the volatility of the
fuel relative to Tier 3 E10 certification fuel. This is because the
volatility plays a significant role in these evaporative emission
sources independent of the level of ethanol concentration in the fuel.
For this sub sim determination, we are evaluating whether E15 at 9.0
psi is sub sim to Tier 3 E10 certification fuel at 9.0 psi. In general,
if two fuels have the same RVP, the expected refueling, diurnal, and
running loss evaporative emissions from the two fuels would be similar
regardless of the ethanol content. In this situation, since there is no
difference in RVP, E15 at 9.0 psi RVP would be expected to have
essentially identical evaporative emissions to E10 at 9.0 psi RVP from
refueling, diurnal, and running loss emissions sources. We find that
E15 at 9.0 psi RVP is sub sim to Tier 3 E10 certification fuel at 9.0
psi RVP for Tier 3 light-duty motor vehicles.
c. Materials Compatibility
    Materials compatibility is a key factor in considering what fuels
or fuel additives are sub sim to certification fuel, insofar as poor
materials compatibility can lead to serious exhaust and evaporative
emission compliance problems not only immediately upon use, but
especially over the full useful life of vehicles and engines. In the
E15 partial waivers, we determined that the use of E15 in MY2001 and
newer light-duty motor vehicles ``will not [result in] materials
compatibility issues that lead to exhaust or evaporative emissions
exceedances.'' \153\ We explained that ``[n]ewer motor vehicles, such
as Tier 2 and NLEV vehicles (MY2001 and newer), on the other hand, were
designed to encounter more regular ethanol exposure compared to earlier
model year motor vehicles'' since EPA's in-use verification program
would require auto manufacturers to place more ``emphasis on real world
motor vehicle testing'' prompting manufacturers to consider
commercially available fuels containing ethanol when developing and
testing their emissions systems.\154\ Based on this assessment, in
addition to confirmatory data from DOE's extensive test program that
aged MY2001 and newer motor vehicles up to 120,000 miles on E15, we
concluded that MY2001 and newer motor vehicles would not have materials
compatibility issues with E15.
---------------------------------------------------------------------------

    \153\ See 75 FR 68122-68123 (November 4, 2010); 76 FR 4681
(January 26, 2011).
    \154\ See 75 FR 68122 (November 4, 2010).
---------------------------------------------------------------------------

    Since granting the E15 partial waivers, E15 is now used as an aging
fuel for service accumulation for evaporative durability testing.\155\
Auto manufacturers have used E15 for service accumulation for
evaporative durability testing since at least MY2014. This means that
many Tier 2 vehicles since MY2014 and all Tier 3 vehicles have been
aged on E15 and have been designed with materials capable of handling
E15 for extended periods of time. As such, we expect that Tier 3
vehicles would have similar, if not better, materials compatibility
with E15 compared to MY2001 and newer motor vehicles since Tier 3
vehicles since manufacturers are required to use E15 as an aging fuel
for evaporative durability testing and therefore design these motor
vehicles to encounter E15 in-use.
---------------------------------------------------------------------------

    \155\ See 40 CFR 86.1824-08(f)(1).
---------------------------------------------------------------------------

    Therefore, we would not expect any materials compatibility issues
from E15 in Tier 3 vehicles and we find that E15 would have
substantially similar materials compatibility effects as Tier 3 E10
certification fuel.
d. Driveability
    A change in the driveability of a motor vehicle that results in
significant deviation from normal operation (e.g., stalling,
hesitation, etc.) would result in increased emissions. These increases
may not be demonstrated in the emission certification test cycles but
instead are present during in-use operation. In addition to consumer
dissatisfaction, a motor vehicle stall and subsequent restart can
result in significant increases in emissions because emission rates are
typically highest during vehicle starts, especially cold starts.
Further, concerns exist if the consumer or operator tampers with the
motor vehicle in an attempt to correct the driveability issue since
consumers may attempt to modify a motor vehicle from its original
certified configuration. Thus, in defining substantially similar we
have considered whether fuels or fuel additives have an adverse effect
on driveability relative to certification fuel.
    We concluded in the E15 partial waivers that we did not believe
that E15 would cause driveability concerns for

MY2001 and newer motor vehicles. We reviewed the data and information
from the over 30 different test programs evaluated to grant the E15
partial waivers and we found ``no specific reports of driveability,
operability or on-board diagnostics (OBD) issues across many different
vehicles and duty cycles including lab testing and in-use operation.''
\156\
---------------------------------------------------------------------------

    \156\ See 76 FR 4681-82 (January 26, 2011).
---------------------------------------------------------------------------

    After granting the partial E15 waivers, we believe that late model
Tier 2 and Tier 3 vehicles also have better capability of operating on
E15, since as mentioned above, auto manufacturers have been required to
use E15 as an aging fuel for evaporative durability aging since at
least MY2014.
    We also believe that the producers and distributors of gasoline
adhere to ASTM specifications for gasoline (i.e., ASTM D4814),\157\
which helps address the driveability of gasoline that contains up to 15
volume percent ethanol. As E15 has been in the market since at least
2012, industry, through ASTM International, has worked to develop
voluntary consensus-based standards to help ensure the quality of E15
made and used in the marketplace. For example, ASTM D4814-18c includes
language to ensure that gasoline-ethanol blends have certain physical
and chemical characteristics, such as distillation parameters falling
within specified ranges, to ensure that when the gasoline-ethanol
blended fuel is used, driveability issues will not arise.\158\
---------------------------------------------------------------------------

    \157\ ASTM Standard D4814, 2019, ``Standard Specification for
Automotive Spark-Ignition Engine Fuel,'' ASTM International, West
Conshohocken, PA, 2003, DOI: 10.1520/C0033-03, https://www.astm.org.
    \158\ Id.
---------------------------------------------------------------------------

    For these reasons, we find that E15 would have similar driveability
characteristics to Tier 3 E10 certification fuel for Tier 3 light-duty
motor vehicles.
e. Conclusion
    For reasons described above, we find that E15 is substantially
similar to Tier 3 E10 certification fuel when E15 is used in Tier 3
vehicles (i.e., MY2020 and newer light-duty motor vehicles). As
discussed above, when interpreting which fuels and fuel additives are
sub sum to certification fuel under CAA sec. 211(f)(1), we consider the
potential effects that a new fuel or fuel additive may have on a motor
vehicle's emissions (exhaust and evaporative), materials compatibility,
and driveability. Regarding emissions, we expect that E15 would exhibit
similar exhaust and evaporative emissions for Tier 3 vehicles certified
on Tier 3 E10 certification fuel. For materials compatibility and
driveability, we find E15 is sub sim since E15 is being used as a
service accumulation fuel for evaporative emissions aging and for the
reasons described in the E15 partial waivers regarding materials
compatibility and driveability for MY2001 and newer light-duty motor
vehicles. For all the reasons described above, we find E15 is sub sim
to Tier 3 E10 certification fuel for Tier 3 light-duty motor vehicles.
7. Technical Rationale for MY2001-2019 Light-Duty Motor Vehicles
    We find that E15 is sub sim to Tier 3 E10 certification fuel in
MY2001-2019 light-duty motor vehicles. As discussed in Section II.C.4,
it is necessary to consider how E15 would perform relative to Tier 3
E10 certification fuel in each class of vehicles, engines, and
equipment. In the E15 partial waivers, we considered the relative
effects of E15 to E10 when used in these vehicles as a basis to
determine that MY2001-2019 light-duty motor vehicles will not
experience issues with materials compatibility and driveability.\159\
Additionally, as described above in the analysis for Tier 3 vehicles,
much of the emissions testing to date to evaluate the effects of E15
has been conducted on vehicles representative of MY2001-2019 light-duty
vehicles. Based on this existing data and our prior engineering
judgment expressed in the E15 partial waivers, we have concluded that
E15, with its additional oxygen content and identical RVP relative to
Tier 3 E10 certification fuel, would have effects on emissions,
materials compatibility, and drivability substantially similar to E10
in MY2001-2019 light-duty motor vehicles.
---------------------------------------------------------------------------

    \159\ See 75 FR 68124 (November 4, 2010) and 76 FR 4681-4682
(January 26, 2011).
---------------------------------------------------------------------------

a. Exhaust Emissions
    In the E15 partial waivers, we argued that auto manufacturers
developed vehicles around MY2001 to accommodate in-use exposure to E10,
and that this accommodation would result in similar performance of
emissions, materials compatibility, and driveability on E15.\160\ We
also pointed to the large compliance margins in certified exhaust
emissions for NLEV and Tier 2 vehicles (collectively MY2001-2019
vehicles) in the E15 waiver decisions.\161\ We contextualized the
relatively small changes in emissions as a small fraction of the
compliance margin and argued that these small changes would not cause
MY2001-2019 motor vehicles to exceed their emissions standards.\162\ We
continue to believe that our engineering analysis presented in the E15
waivers is appropriate, and that MY2001-2019 motor vehicles will have
substantially similar exhaust emissions on E15 when compared to Tier 3
E10 certification fuel.
---------------------------------------------------------------------------

    \160\ See 75 FR 68125-68126 (November 4, 2010) and 76 FR 4667
(January 26, 2011).
    \161\ See 75 FR 68111 (November 4, 2010) and 76 FR 4669 (January
26, 2011).
    \162\ Id.
---------------------------------------------------------------------------

    As we stated in the first E15 partial waiver, ``the largest
improvements to emission controls and hardware durability came after
2000 with the introduction of several new emission standards and
durability requirements forcing manufacturers to better account for the
implications of in use fuels on the evaporative and exhaust emission
control systems.'' \163\ Overall, the transition from Tier 1 (generally
pre-MY2000 and older vehicles) to NLEV (generally MY2001-2003) and then
to Tier 2 (generally MY2004-2019) exhaust standards called for design
changes that all moved in the same direction of increased control of
exhaust emissions through increasingly sophisticated emissions control
systems aimed at reducing the level of emissions created by the
combustion of the fuel in the engine combined with increased control of
these emissions by the catalyst system. This increasing sophistication
was based on better air fuel ratio control, and increased efficiency,
durability and faster light-off of the catalyst. While Tier 2 standards
called for the most sophisticated engine and catalyst system designs at
the time, the NLEV standards prompted major redesign efforts by
manufacturers that were later expanded and advanced even further to
meet, and earn credits towards compliance with, Tier 2 standards. From
an engineering perspective, the emissions control systems of pre-Tier
2, NLEV vehicles are significantly more robust than those used in
MY2000 and older motor vehicles and more like those of Tier 2 motor
vehicles in terms of the degree of sophistication of engine controls
and catalyst technology. In the second E15 waiver decision, we reviewed
the available emission control technologies of NLEV vehicles to
determine that they had adapted most of the control strategies that
were employed in Tier 2 vehicles.\164\ These control strategies
involved controlling for oxygen content of fuels to largely reduce the
risks associated with gasoline-ethanol blended fuel use.
---------------------------------------------------------------------------

    \163\ See 75 FR 68125 (November 4, 2010).
    \164\ See 76 FR 4669 (January 26, 2011).

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

    Furthermore, we highlighted that another important regulatory
change for improving the exhaust emissions control durability of
MY2001-2006 light-duty motor vehicles was the Compliance Assurance
Program (``CAP2000''), which took effect by MY2000 for light-duty motor
vehicles. CAP2000 placed more emphasis on in-use performance of vehicle
emission controls, including the potential impacts of operation from
different available in-use fuels. In particular, the In-use
Verification Program (IUVP) introduced under CAP2000 requires
manufacturers to perform exhaust and evaporative emissions tests on
customer vehicles in the in-use fleet to confirm the durability
projections that manufacturers make at certification. These motor
vehicles would now be exposed to gasoline-ethanol blends in use.
    Another consideration in our engineering analysis in the second E15
waiver decision was the extent to which MY2001-2006 light-duty motor
vehicles emit at levels below the applicable standards and therefore
have a compliance margin. Compliance margins are generally designed
into motor vehicles by manufacturers to account for possible variations
in production vehicles and changes to vehicle emissions control systems
from actual field usage, such as how the vehicle is typically operated
and the type of fuel used. The larger the compliance margin, the more
likely it is that vehicles would accommodate any emissions increases
from fueling with E15 and continue to meet emission standards in-use.
In the second E15 waiver decision, we surveyed the certification data
for MY2001-2006 motor vehicles and the results showed that the average
full useful life compliance margin (which accounts for in-use
deterioration) for the entire MY2001- 2006 light-duty motor vehicle
fleet was approximately 66 percent.\165\ We also reviewed in-use data
from the IUVP program, which indicated that motor vehicles actually
achieved a similar compliance margin when operated in real-world
conditions.\166\ The size of the compliance margins for MY2001-2006
light-duty motor vehicles suggests manufacturers were in fact designing
and building motor vehicles that were significantly cleaner than
required as part of a planned migration to technologies capable of
meeting the tighter Tier 2 standards.
---------------------------------------------------------------------------

    \165\ See 76 FR 4669 (January 26, 2011).
    \166\ See 75 FR 68111-68112 (November 4, 2010) and 76 FR 4669
(January 26, 2011).
---------------------------------------------------------------------------

    We relied on the available literature, primarily the data collected
from the DOE catalyst study, to confirm our engineering analysis of the
emissions behavior of NLEV and Tier 2 vehicles. These data showed that
E15 would not cause NLEV or Tier 2 vehicles to exceed their emissions
standards both in the short- and long-term. Furthermore, most of the
data discussed in Sections II.C.6.a and II.F were based on tests
conducted on MY2001-2019 motor vehicles and we believe that the
estimated emissions changes from using E15 relative to Tier 3 E10
certification fuel or E10 market fuel in MY2001-2019 are representative
of vehicle technologies classes in this time period (i.e., NLEV, Tier
2, and early Tier 3 vehicles).
    Because of the extensive analysis in the E15 waiver decisions and
the large compliance margins in the MY2001-2019 light-duty motor
vehicle fleet, we find that E15 is sub sim to Tier 3 E10 certification
fuel when used in those vehicles.
b. Evaporative Emissions
    As mentioned in Section II.C.6.b, we evaluate evaporative emissions
in terms of six sources of evaporative emissions: (1) Diurnal
emissions, (2) refueling emissions, (3) hot soak, (4) running loss, (5)
permeation, and (6) emissions from unintended leaks. In the E15 waiver
decisions,\167\ we explained that as with exhaust emissions, emission
control improvements adopted in response to applicable regulatory
requirements are important to the consideration of the potential impact
of a fuel or fuel additive on evaporative emissions. A number of
regulatory actions occurred by MY2001 that placed an emphasis on the
control of evaporative emissions and on real-world testing of motor
vehicles, which in turn led to changes in evaporative emission control
systems. These regulatory changes, together with test data reviewed in
the E15 waivers,\168\ support the conclusion that MY2001-2019 light-
duty motor vehicles operated on E15 at 9 psi RVP would have similar
evaporative emissions if those vehicles were operated on Tier 3 E10
certification fuel.
---------------------------------------------------------------------------

    \167\ See 75 FR 68112-68113 (November 4, 2010) and 76 FR 4673-
4674 (January 26, 2011).
    \168\ See 75 FR 68120 (November 4, 2010) and 76 FR 4663-4664
(January 26, 2011).
---------------------------------------------------------------------------

    As mentioned in Section II.C.6.b, we evaluated the effects E15
would have relative to E10 for hot soak, permeation, and unintended
leak evaporative emissions in MY2001-2019 motor vehicles in the E15
waivers. We found that motor vehicles designed and aged on E10 for
evaporative emissions durability would have similar hot soak,
permeation, and unintended leak evaporative emissions if operated on
E15. As explained in the first E15 partial waiver, since these elements
are largely a function of the materials used to design the evaporative
emission controls, if an auto manufacturer designed a system to
encounter a gasoline-ethanol blended fuel in-use, it is likely that the
vehicle's evaporative emissions control would handle E10 and E15
similarly. Therefore, we find that E15 is sub sim to Tier 3 E10
certification fuel for hot soak, permeation, and unintended leak
evaporative emissions for MY2001-2019 motor vehicles.
    Also, as mentioned in Section II.C.6.b, diurnal, refueling, and
running loss emissions are mostly a function of the volatility of the
gasoline used. If two fuels had the same volatility, we would expect
the same or similar diurnal, refueling, and running loss emissions. As
we are only considering whether E15 at 9.0 psi RVP is sub sim to Tier 3
E10 certification fuel with 9.0 psi RVP we can conclude that E15 at 9.0
psi RVP is sub sim to Tier 3 E10 certification fuel in MY2001-2019
light-duty motor vehicles. We base this finding on the fact that E15 at
9.0 psi would have the same volatility as Tier 3 E10 certification
fuel.
c. Materials Compatibility
    We find that E15 at 9 psi RVP is substantially similar to Tier 3
E10 certification fuel when used in MY2001-2019 light-duty motor
vehicles as it relates to materials compatibility. Materials
compatibility is a factor in considering whether a fuel is sub sim
since poor materials compatibility can lead to serious exhaust and
evaporative emissions compliance problems not only immediately upon
using the new fuel or fuel additive, but especially over time.
    Similar to Tier 3 vehicles, pre-Tier 2 and Tier 2 vehicles (MY2004-
2019) were aged with E10 for evaporative durability beginning with
MY2004. Due to this long-term exposure of E10, we explained in the
first E15 waiver decision that these motor vehicles would not have
materials compatibility issues. For NLEV vehicles, in the second E15
waiver decision, we argued that ``the CAP2000 in-use testing and
durability demonstration requirements as well as the introduction of
OBD leak detection monitors and enhanced evaporative emission test
procedures have led manufacturers to design vehicles using materials
that will continue to function properly with respect to evaporative
emissions when

gasoline-ethanol blends are used.'' \169\ This includes materials
compatible with long-term use of gasoline-ethanol blends, as the
standards apply for the useful life of the vehicle, and the IUVP test
program and the OBD leak detection requirement monitor compliance
throughout the useful life. We noted in the second E15 waiver decision
that data from IUVP, EPA's in-use surveillance program, and
manufacturer emission defect information reports had not detected any
failures attributable to ethanol up to E10 in these vehicles.\170\
---------------------------------------------------------------------------

    \169\ See 76 FR 4681 (January 26, 2011).
    \170\ See 76 FR 4681 (January 26, 2011).
---------------------------------------------------------------------------

    Based on our engineering judgment discussed in the E15 waiver
decisions, we expect that there will not be materials compatibility
issues with E15 in MY2001-2019 light-duty motor vehicles. Therefore, we
conclude that E15 at 9.0 RVP is sub sim to Tier 3 E10 certification
fuel in MY2001-2019 light-duty motor vehicles.
d. Driveability
    We find that E15 at 9.0 psi RVP is substantially similar to Tier 3
E10 certification fuel when used in MY2001-2019 light-duty motor
vehicles as it relates to driveability. As mentioned in Section
II.C.7.a and described in the E15 partial waivers, auto manufacturers
developed light-duty motor vehicles to use gasoline-ethanol blends that
were becoming more prevalent in the marketplace by MY2001. This was
tied to the implementation of new vehicles emission standards that
focused on in-use performance in fuels; namely, the CAP 2000 program
and NLEV for exhaust emissions, and the enhanced evaporative emission
standards.\171\ Additionally, as auto manufacturers began complying
with the Tier 2 standards (beginning with MY2004), auto manufacturers
were required to use E10 as an aging fuel for evaporative emission
durability testing.\172\ Due to this focus on in-use performance for
MY2001 and newer light-duty motor vehicles, which were designed to run
on E10 in use, we believe E15 would affect driveability similarly to
Tier 3 E10 certification fuel used in these vehicles.
---------------------------------------------------------------------------

    \171\ See 75 FR 68104 (November 4, 2010) and 76 FR 4680 (January
26, 2011).
    \172\ See 40 CFR 86.113-04.
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    We evaluated driveability of MY2001-2019 vehicles extensively in
the E15 partial waivers. In the first E15 partial waiver, we found that
``[t]here is no evidence from any of the test programs cited by Growth
Energy or in the data from the DOE Catalyst Study of driveability
issues for Tier 2 motor vehicles fueled with E15 that would indicate
that use of E15 would lead to increased emissions or that might cause
motor vehicle owners to want to tamper with the emission control system
of their motor vehicle.'' \173\ In the second E15 partial waiver, we
found that ``[t]he Agency's review of the data and information from the
different test programs finds no specific reports of driveability,
operability or OBD issues across many different vehicles and duty
cycles including lab testing and in-use operation [in MY2001-2006
light-duty motor vehicles].'' \174\
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    \173\ See 75 FR 68097 (November 4, 2010).
    \174\ See 76 FR 4681-4682 (January 26, 2011).
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    Based on both our engineering rationale that MY2001 and newer
light-duty motor vehicles were designed by auto manufacturers to
operate on gasoline-ethanol blends and our thorough review of the
available literature in the E15 partial waivers, which showed no
driveability, operability or OBD issues across over 30 reviewed studies
on E15 covering MY2001 and newer vehicles, we find that E15 at 9.0 psi
RVP is substantially similar to Tier 3 E10 certification fuel when used
in MY2001-2019 light-duty motor vehicles as it relates to driveability.
e. Conclusion
    We find that E15 at 9.0 psi RVP is sub sim to Tier 3 E10
certification fuel when used in MY2001-2019 vehicles. In conjunction
with our finding that E15 at 9.0 psi RVP is sub sim to Tier 3 E10
certification fuel when used in MY2020 and newer light-duty motor
vehicles (i.e., Tier 3 certified light-duty vehicles) as discussed in
Section II.C.6, these findings collectively mean that we find that E15
at 9.0 psi RVP is sub sim to Tier 3 E10 certification fuel when used in
MY2001 and newer light-duty vehicles.
8. Technical Rationale for Other Vehicles, Engines, and Equipment
    We conducted an analysis of whether E15 is substantially similar to
E10 certification fuel for MY2000 and older light-duty motor vehicles,
heavy-duty gasoline-fueled motor vehicles, and nonroad vehicles,
engines, and equipment. For the reasons explained below, we conclude
that E15 is not sub sim to E10 certification fuel for these types of
vehicles and engines.
a. MY2000 and Older Light-Duty Motor Vehicles
    We conclude that E15 would not be substantially similar to Tier 3
E10 certification fuel used in MY2000 and older light-duty motor
vehicles. As we argued in the first E15 partial waiver decision and in
the MMR, MY2000 and older light-duty motor vehicles were generally not
designed to operate on gasoline-ethanol blended fuels.\175\ We
determined that E15 in these vehicles could lead to increases in
emissions that result in vehicles exceeding certified emission
standards and issues with materials compatibility as auto manufacturers
likely did not use components compatible with ethanol in fuel systems.
---------------------------------------------------------------------------

    \175\ See 75 FR 68125-68126 (November 4, 2010) and 76 FR 44412
(July 25, 2011).
---------------------------------------------------------------------------

    MY2000 and older light-duty motor vehicles have much less
sophisticated emissions control systems compared to more modern
vehicles and, may experience conditions that lead to immediate emission
increases and may exceed their emission standards if operated on E15.
Vehicles produced prior to the mid-1980s were equipped primarily with
carbureted engines. The air/fuel (A/F)ratio of the carburetor is preset
at the factory based on the expected operating conditions of the engine
such as ambient temperature, atmospheric pressure, speed, and load. As
a result, carburetors have ``open loop'' fuel control, which means that
the air and fuel are provided at a specified, predetermined ratio that
is not automatically adjusted during vehicle operation. As fuel
composition can vary, an engine with a carburetor and open loop fuel
control would never detect whether the desired A/F ratio was achieved.
Since the vehicles produced prior to the mid-1980s operated ``open
loop'' all of the time with no ability to react to changes in the A/F
ratio, the addition of ethanol to the fuel tended to make the A/F ratio
leaner, typically resulting in an immediate emission impact of reducing
HC and CO emissions, but increasing NOX emissions. However,
some of these older open loop systems already operate at the lean edge
of combustion on current commercial fuels so an increase in ethanol may
cause them to begin to misfire resulting in HC and CO increases.
Concerning long-term exhaust emissions, in the first E15 waiver, we
concluded that for MY2000 and older light-duty motor vehicles,
enleanment \176\ resulting in higher exhaust temperatures could cause
accelerated catalyst deterioration which

would result in higher emissions long-term.\177\
---------------------------------------------------------------------------

    \176\ Enleanment refers to increasing the amount of oxygen in
the mixture of air and fuel that enters the engine for combustion.
At any one air to fuel ratio, adding ethanol to the fuel adds
additional oxygen to the mixture of air and fuel, tending to enlean
the mixture.
    \177\ See 75 FR 68128 (November 4, 2010).
---------------------------------------------------------------------------

    Concerning materials compatibility, in the first E15 partial waiver
we found that ``a number of pre-Tier 2 motor vehicles, including Tier 0
motor vehicles (from the 1980s to 1995) and Tier 1 motor vehicles (from
1996 to 2001), may have been designed for only limited exposure to E10
and consequently may have the potential for increased material
degradation with the use of E15 even though they are beyond their
useful life requirements.'' \178\ We argued further that degredation of
fuel systems and emission controls from compatibility issues could
result in higher emissions and emission control failure due to
corrosion.
---------------------------------------------------------------------------

    \178\ See 75 FR 68129 (November 4, 2010).
---------------------------------------------------------------------------

    Due to the potential increases in vehicles emissions and issues
with materials combability, we prohibited MY2000 and older light-duty
motor vehicles from using E15.\179\ We continue to believe that MY2000
and older light-duty motor vehicles were not designed to operate on E15
gasoline-ethanol blends and that E15 would not be sub sim to Tier 3 E10
certification fuel in those vehicles. As we found in the first E15
waiver decision, we believe that going from E10 to E15 in these
vehicles could damage the emission controls and lead to increased
emissions. Therefore, we conclude that E15 is not sub sim to Tier 3 E10
certification fuel in MY2000 and older light-duty motor vehicles.
---------------------------------------------------------------------------

    \179\ See 76 FR 44448 (July 25, 2011).
---------------------------------------------------------------------------

b. Heavy-Duty Gasoline-Fueled Motor Vehicles
    As discussed in the first E15 waiver decision and the MMR, we have
concerns for E15 use in heavy-duty gasoline-fueled motor vehicles that
are similar to our concerns regarding E15 use MY2000 and older
vehicles.\180\ We believe that heavy-duty gasoline-fueled motor
vehicles have historically lagged in adoption of adaptive fuel controls
similar to MY2000 and older vehicles, and we have no new information to
cause us to reconsider E15 use in these vehicles. For all of the
reasons discussed in Section II.C.8.a, we find that E15 is not sub sim
to Tier 3 E10 certification fuel for heavy-duty gasoline fueled motor
vehicles.
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    \180\ See 75 FR 68138 (November 4, 2010) and 76 FR 44409 (July
25, 2011).
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c. Nonroad Vehicles, Engines, and Equipment (Including Motorcycles and
Marine Engines)
    Due to the potential effects on emissions and materials
compatibility, we cannot determine that E15 is sub sim to Tier 3 E10
certification fuel when used in nonroad products, motorcycles, or
marine engines. The sub sim definition in this action for E15 restricts
the applicability of the sub sim definition from applying to nonroad
vehicles, engines, and equipment (``nonroad products''), highway and
off-highway motorcycles (collectively called ``motorcycles''), and
marine engines. As discussed in Section II.C.9, we believe it
appropriate to limit the applicability of a sub sim definition to those
vehicles, engines, and equipment for which EPA is able to determine
that the fuel or fuel additive is suitable for use.
    In the first E15 partial waiver, we denied the E15 waiver request
for all nonroad vehicles, engines, and equipment (``nonroad
products''). As described in detail in the first E15 partial waiver,
nonroad products typically have less complex engine designs, fuel
systems, and controls than light-duty motor vehicles.\181\ We also
expressed concerns with the use of E15 in nonroad products,
particularly with respect to long-term exhaust and evaporative
emissions and materials compatibility.\182\ The limited information
available in the public domain at the time of the first E15 waiver
decision, supported our decision to not grant the E15 waiver request
for nonroad products.\183\ Additionally, we used our engineering
rationale and the data evaluated from the first E15 waiver decision to
prohibit the use of E15 in nonroad products under CAA sec. 211(c) in
the MMR.\184\
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    \181\ See 75 FR 68098 (November 4, 2010).
    \182\ See 75 FR 68134-68137 (November 4, 2010).
    \183\ See 75 FR 68137 (November 4, 2010).
    \184\ See 76 FR 44448 (July 25, 2011).
---------------------------------------------------------------------------

    We have similar concerns with E15 use in motorcycles and marine
engines as these vehicles and engines have similar emission controls to
other classes of nonroad products. These concerns were the basis for
the denial of the E15 waiver request for all motorcycles and marine
engines and extending the prohibition on E15 use in motorcycles and
marine engines.
    Since the E15 waivers and the MMR, little has changed with respect
to ability of nonroad products to utilize E15. They continue to be
certified on E0 and designed to run on gasoline-ethanol blends only up
to E10. As highlighted in their public comments, the manufacturers of
such engines continue to press for the need for greater outreach,
education, and misfueling mitigation efforts beyond those already in
place to protect their customers from E15, and the marine manufacturers
have been actively testing isobutanol in concert with butanol coalition
members to gain approval for its use in lieu of ethanol entirely due to
their ongoing concerns with the use of ethanol at all in the marine
environment. For these reasons, the sub sim determination in this
action excludes from its scope these vehicles, engines, and equipment.
This exclusion in conjunction with the prohibition on E15 use in these
products promulgated under CAA sec. 211(c) in the MMR will continue to
preclude the use of E15 in these products.
9. Limitations of ``Substantially Similar'' Interpretative Rulemaking
    CAA sec. 211(f)(1)(B) prohibits fuel or fuel additive manufacturers
from first introducing into commerce, or increasing the concentration
in use of, any fuel or fuel additive for use by any person in motor
vehicles which is not substantially similar to any fuel or fuel
additive utilized in the certification of motor vehicles or engines
under CAA sec. 206. As explained above, we have interpreted the
``substantially similar'' provision several times to allow the
introduction into commerce of certain fuel blends. The language of CAA
sec. 211(f)(1) does not address whether and how EPA can restrict its
determination that a particular fuel is ``substantially similar'' to a
certification fuel. Given the fact that there have now been multiple
certification fuels since 1977, when CAA sec. 211(f)(1) was first
enacted, we believe it is reasonable to interpret this provision as
allowing EPA to make a sub sim determination with respect to the use of
the new fuel within certain parameters, where the parameters are
intended to avoid the kinds of problems that prompted Congress to enact
the general prohibition against introduction into commerce of fuels
that are neither substantially similar nor have a CAA sec. 211(f)(4)
waiver. Additionally, as discussed in Sections II.C.6-8, despite being
sub sim for certain light-duty vehicles, E15 is inappropriate for use
in vehicles, engines, and equipment other than MY2001 and newer light-
duty vehicles. Therefore, without the sub sim determination being
limited to the parameters described in this section, there would be no
basis for a conclusion that E15 is ``substantially similar'' to Tier 3
certification fuel.
    Congress did not speak directly to the question of whether CAA sec.
211(f)(1) provides EPA with authority to make a sub sim determination
that is subject to appropriate parameters, and we believe that a sub
sim determination within reasonable parameters intended to

ensure that the fuel at issue is in fact ``substantially similar'' to
the relevant certification fuel is appropriate. Here, where EPA's sub
sim determination for E15 is based on a determination that E15 is
substantially similar to a certification fuel that is used to certify
only a subset of the vehicle fleet, and the Agency has already
determined that E15 cannot be used in certain vehicles and engines, it
is necessary for EPA's sub sim determination to acknowledge certain
parameters in order to ensure that the purpose of CAA sec. 211(f)(1) is
maintained. As explained in Section II.A.1, the intent behind the
enactment of CAA sec. 211(f)(1) was to prevent of the use of any new or
recently introduced additive to unleaded gasoline that could impair the
emission performance of vehicles \185\--as explained above, this is the
same rationale underpinning the parameters within which we make this
final sub sim determination. Congress recognized that the analysis
required to control or prohibit the manufacture or introduction into
commerce of a fuel or fuel additive under CAA sec. 211(c) may be a
lengthy process.\186\
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    \185\ S. Rep. No. 95-127, 95th Cong., 1st Sess. 90 (1977).
    \186\ Id.
---------------------------------------------------------------------------

    Given this context and the legislative history leading to the
enactment of CAA sec. 211(f)(1), the parameters within which we make
our sub sim determination today represent a reasonable exercise of our
CAA sec. 211(f)(1) authority.
    As discussed below, in this action we are establishing criteria on
our E15 sub sim finding consistent with the rationale underpinning the
enactment of CAA sec. 211(f)(1), and our prior interpretation of our
authority to make a sub sim finding within certain parameters under CAA
sec. 211(f)(1) or to place certain conditions on a CAA sec. 211(f)(4)
waiver from sub sim. Given the direct impact on emissions and the
indirect impact on emission through impacts on materials compatibility,
and driveability, the parameters within which we are making our E15 sub
sim finding address these three areas.
    One implication of a sub sim interpretation that includes E15 under
CAA sec. 211(f)(1) would be that a waiver under CAA sec. 211(f)(4) will
no longer be necessary for E15 to be introduced into commerce. This
would in effect remove the conditions of the E15 partial waivers
imposed on fuel and fuel additive manufacturers, in the absence of any
limitations on the sub sim interpretation. This would mean that the
conditions in the E15 partial waivers designed to limit the
introduction into commerce of E15 to only MY2001 and newer light-duty
motor vehicles would not apply. We have already promulgated parallel
restrictions in our regulations in the E15 MMR rulemaking at 40 CFR
part 80, subpart N.\187\ However, some conditions in the E15 partial
waivers are not part of the MMR. One such condition is the requirement
that fuel and fuel additive manufacturers have an EPA-approved
misfueling mitigation plan (MMP) prior to introducing E15 into
commerce.
---------------------------------------------------------------------------

    \187\ See 75 FR 68127-68138 (November 4, 2010).
---------------------------------------------------------------------------

    While MMPs generally commit fuel and fuel additive manufacturers to
adhere to regulatory requirements of the MMR, MMPs also commit these
manufacturers to participate in public outreach on the appropriate use
of E15 and allow for specific, additional misfueling mitigation
measures that may apply in a manufacturer's specific situation. We
believe that the continued existence of MMPs is important when finding
that E15 is sub sim. The MMPs help prevent the use of E15 in MY2000 and
older motor vehicles, nonroad vehicles, engines, and equipment
(including motorcycles, and heavy-duty motor vehicles). Without the
MMPs, there is an increased risk of misfueling which would directly
impact the effects of the E15 on emissions, materials compatibility and
drivability in MY2000 and older motor vehicles and nonroad, heavy-duty,
and motorcycle vehicles and engines. We denied the E15 waiver request
for MY2000 and older motor vehicles, nonroad vehicles, engines, and
equipment (including motorcycles, and heavy-duty motor vehicles) due to
our engineering assessment that these vehicles, engines, and equipment
may experience emissions failures over these vehicles, engines, and
equipments' full useful lives.
    Also, as discussed above, in the MMR we concluded that under CAA
sec. 211(c)(1)(A), the likely result would be increased VOC, CO, and
NOX emissions were these particular engines, vehicles, and
equipment to use E15. The prohibitions and regulatory requirements were
designed to help mitigate the misfueling of E15 in these vehicles.
There are still millions of MY2000 and older motor vehicles on the road
(although they will over time make a smaller contribution to vehicle
miles travelled) and hundreds of millions of pieces of nonroad
equipment not designed for and prohibited from E15 use. The existing
conditions on the E15 partial waivers under CAA sec. 211(f)(4) help
ensure E15 fuel quality and mitigate the misfueling of vehicles,
engines, and equipment and we believe it is appropriate to continue to
limit our sub sim determination to a determination that E15 is sub sim
to Tier 3 E10 certification fuel only under parameters that reflect the
existing conditions on the E15 partial waivers.
    We also sought comment on whether this proposed sub sim
interpretation for E15 should be limited to the subset of the national
vehicle and engine fleet to which the current E15 waivers apply (MY2001
and newer light-duty motor vehicles) or on which our assessment in
Section II.C.5 of the NPRM is based (i.e., only to vehicles and engines
certified using Tier 3 E10 certification fuel). After considering these
comments, we find it appropriate to limit the applicability of our
substantially similar determination in this case to certain classes of
vehicles, engines, and equipment. The record has not changed with
respect to the inability of older vehicles, nonroad equipment,
motorcycles, or heavy-duty trucks to use E15, which formed the basis of
our denial of the E15 waiver request for such vehicles, engines, and
equipment. Furthermore, our assessment in Section II.C.5 of the NPRM
found that the use of E15 in MY2000 or older light-duty gasoline motor
vehicle, any heavy-duty gasoline motor vehicle or engine, any highway
or off-highway motorcycle, or any gasoline-powered nonroad engines,
vehicles or equipment is not substantially similar to Tier 3 E10
certification fuel. Such a limitation would be in recognition of the
fact that, in contrast to the state of affairs at the time when CAA
sec. 211(f)(1) was enacted, not all gasoline vehicles and equipment are
certified on the same gasoline. All other vehicles, engines, and
equipment prior to Tier 3 used certification fuel without ethanol, and
some nonroad vehicles, engines, and equipment are still certified using
E0. Another condition in the E15 partial waivers is that ethanol
producers must manufacture denatured fuel ethanol that meets industry
established quality standards if used to make E15. This requirement is
not currently part of EPA's fuels regulations. For the new definition
of sub sim for E15 in this action, we are updating criteria that
establishes the physical and chemical parameters for the new definition
of sub sim. We are making these changes largely to ensure that E15 that
is introduced into commerce will continue to be sub sim to Tier 3 E10
certification fuel. We also do not believe that it would make sense to
duplicate the criteria from the 2008 sub sim

interpretation, especially since many of these updates are focused on
accommodating a marketplace where E10 is predominant and E10 is now a
certification fuel. For the new definition of sub sim for E15 in this
action, we are updating the ASTM International specification references
for volatility and driveability for the gasoline-ethanol blended fuels.
We are also including a reference to the latest ASTM International
denatured fuel ethanol (DFE) quality specification. Finally, we are
updating the criteria for the use of additional fuel additives to be
consistent with the Tier 3 gasoline sulfur requirements.
    We received public comments suggesting that we update the reference
to the ASTM standards for sub sim to the latest version of ASTM
International standard D4814. One commenter noted that since E15 has a
large effect on middle distillation (T50 in particular), EPA should
reference the latest ASTM D4814 standard for gasoline as this standard
helps ensure that gasoline-ethanol blends continue to meet the
driveability index. The driveability index is a measure in the ASTM
D4814 standard based primarily on the distillation characteristics of a
fuel that helps ensures that spark-ignition engines operate correctly
on gasoline. As discussed in Section II.C.6.d, fuels that cause issues
with driveability can either directly increase emissions or result in
consumers tampering with certified emissions configurations, which can
result in increases in emissions. We agree with commenters that we
should reference the latest version of ASTM D4814 as it relates to
ensuring that the driveability index is met for gasoline-ethanol blends
containing up to 15 volume percent. Therefore, we are specifying that
only gasoline-ethanol blends that meet the applicable vapor pressure
and distillation class requirements as specified in ASTM International
Standard D4814-19 are considered physically and chemically
substantially similar to Tier 3 E10 certification fuel.
    Additionally, we believe it is appropriate that DFE used to produce
E15 also needs to meet the latest ASTM International specifications for
DFE, ASTM D4806-19. In the E15 partial waiver decisions, we imposed the
condition that DFE used to make E15 under the waivers needed to meet a
prior version of the ASTM ethanol specification. This condition was
imposed in the E15 waivers under CAA sec. 211(f)(4) to help ensure that
certain impurities in ethanol were limited to avoid issues with
materials compatibility and help ensure quality of the gasoline-ethanol
blended fuel when used in a vehicle or engine.\188\ We believe it is
still important to make sure that DFE used to make E15 meets ASTM D4806
specifications to ensure the quality of the E15. This will help ensure
that materials compatibility and driveability are not adversely
affected when E15 is used in 2001 and newer light-duty motor vehicles.
Therefore, we are defining that only E15 made with DFE that meets ASTM
D4806-19 is sub sim.
---------------------------------------------------------------------------

    \188\ See 75 FR 68127-68138 (November 4, 2010).
---------------------------------------------------------------------------

    Finally, we are updating the criteria for additional fuel additives
added to E15 that are introduced into commerce under the sub sim
interpretation in this action to be consistent with fuel additive
requirements for gasoline promulgated in the Tier 3 rule. In prior sub
sim interpretations,\189\ we limited additives under sub sim to a
concentration of no more than 0.25 percent by weight of the finished
fuel and to contribute no more than 15 parts per million (ppm) sulfur
by weight to the finished fuel. In the sub sim interpretation for E15
in this action, we limit additional fuel additive(s) to a concentration
of no more than 1.0 volume percent of the finished fuel and the
additional fuel additive(s) must contribute no more than 3 ppm sulfur
by weight to the finished fuel. Since we are defining E15 as sub sim to
Tier 3 certification fuel when used in MY2001 and newer light-duty
vehicles, we need to consider whether additional additives added to E15
would adversely affect emission controls in MY2001 and newer light-duty
vehicles. We cannot find that an additive that is five times the
specified applicable standard for sulfur content is sub sim to Tier 3
certification fuel, especially in Tier 3 vehicles. The Tier 3 rule set
sulfur standards that would expose light-duty motor vehicles on average
to sulfur levels of 10 ppm. If we issued the prior parameters for fuel
additives under the sub sim interpretation in this action as the prior
sub sim interpretations, this would allow the finished fuel to have a
sulfur level of 25 ppm, or almost equal to the Tier 2 average sulfur
standard of 30 ppm. This could largely negate the purpose of setting
more stringent sulfur specification for Tier 3 certification fuel and
imposing the Tier 3 gasoline sulfur standard. Therefore, we find that
it would be inappropriate to adopt the criteria used in prior sub sim
interpretations. We find that it is more appropriate to adopt the Tier
3 provisions for gasoline additives in the regulations at 40 CFR
80.1613 as these were specifically designed to ensure that Tier 3
light-duty vehicles emissions controls are protected from large
increases in sulfur from gasoline additives.
---------------------------------------------------------------------------

    \189\ See 46 FR 38586 (July 28, 1981), 56 FR 5356 (February 11,
1991), and 73 FR 22281 (April 25, 2008).
---------------------------------------------------------------------------

10. Implications of ``Substantially Similar'' Interpretation
    The new interpretation of ``substantially similar'' that E15 is sub
sim to Tier 3 E10 certification fuel discussed in this section would
make it lawful for refiners and importers to make and introduce into
commerce E15 without the use of the CAA sec. 211(f)(4) E15 partial
waivers.\190\ This interpretation of ``substantially similar'' in
conjunction with the interpretation of CAA sec. 211(h)(4) would extend
the waiver from the CAA sec. 211(h)(1) upper RVP limit from 9.0 psi to
10.0 psi to fuels containing 9-15 percent ethanol during the high ozone
season.
---------------------------------------------------------------------------

    \190\ We are not asking fuel and fuel additive manufacturers who
have existing E15 registrations under the CAA sec. 211(f)(4) waiver
to submit new registrations.
---------------------------------------------------------------------------

    We intend for this definition to coexist with the existing
definition of ``substantially similar'' (hereinafter ``the 2008
definition''). This is appropriate because the 2008 definition is in
comparison to indolene, and the new interpretation is in comparison to
Tier 3 E10 certification fuel. However, because there are now two
certification fuels to which we can draw comparisons, and two
definitions of sub sim relating to each fuel, we think it is important
to describe how fuel and fuel additive manufacturers will continue to
introduce into commerce their fuels and fuel additives and maintain
their registrations under 40 CFR part 79. We intend for the existing
CAA sec. 211(f)(4) waivers promulgated relative to ``indolene'' to
remain available as an option for introduction into commerce for fuels
that are nonetheless sub sim to Tier 3 E10 certification fuel. We have
taken this approach recognizing that removing existing waivers has the
potential to create confusion about the validity of historical
introduction into commerce under these waivers and the continued
validity of existing registrations for fuels and fuel additives under
40 CFR part 79. For the E15, after the sub sim definition in this
action goes into effect, we will presume that fuel and fuel additive
manufacturers that have already registered E15 or ethanol for use in
the production of E15 under 40 CFR part 79 will introduce E15 into
commerce under our new definition of sub sim (as opposed to the

211(f)(4) waiver for E15), unless we are told otherwise through an
update to the fuel or fuel additive manufacturer's registration under
40 CFR part 79. This will allow fuel and fuel additive manufacturers
and downstream parties to introduce E15 with the 1-psi waiver and not
run afoul of the 9.0 psi waiver condition under the CAA sec. 211(f)(4)
waivers without having to update their registrations under 40 CFR part
79.\191\ We believe it would be unnecessarily burdensome to require the
hundreds of registrants of E15 or ethanol for use in the production of
E15 to update their registrations under 40 CFR part 79 to demonstrate
that their E15 or ethanol for use in the production of E15 is sub sim
in light of our finding that E15 is sub sim to E10 certification fuel
in MY2001 and newer light-duty motor vehicles.
---------------------------------------------------------------------------

    \191\ Downstream parties who are not fuel or fuel additive
manufacturers could also introduce E15 into commerce at 10.0 psi
under the waiver conditions, even with today's sub sim
determination, because those conditions only apply to fuel and fuel
additive manufacturers, as discussed in Section II.D.3.
---------------------------------------------------------------------------

    Because the CAA sec. 211(f)(4) waiver is a waiver from being
``substantially similar,'' once E15 is found to be sub sim the waiver
is no longer needed in order to introduce E15 into commerce. However,
as discussed previously, we intend for the CAA sec. 211(f)(4) waiver to
remain available for the introduction of E15 into commerce. Therefore,
as previously explained in Section II.A.3, the deemed to comply
provision in CAA sec. 211(h)(4)(B), which was promulgated at the
inception of the RVP program when industry had just begun blending
ethanol in gasoline and requires that the ethanol portion of the blend
not exceed the highest permissible ethanol content under the CAA sec.
211(f)(4) waiver, would remain effective with respect to E15. The CAA
sec. 211(f)(4) waiver for E15 remains available for the introduction
into commerce of E15, and therefore the statutory ``deemed to comply''
criterion that ``the ethanol portion of the blend does not exceed its
waiver condition under subsection (f)(4) of this section'' can still be
satisfied both by parties that introduce E15 into commerce under the
CAA sec. 211(f)(4) waiver or the CAA sec. 211(f)(1) sub sim finding
because the ethanol content under either is identical. Our regulations
at 40 CFR 80.28, as modified in this action, condition the ``deemed to
comply'' provision on specific ethanol content between 9 and 15 percent
by volume. For reasons discussed in Section II.D.1, we are not
modifying this provision, other than by increasing the maximum
allowable ethanol percent from 10 to 15 to reflect our revised
interpretation of the CAA sec. 211(h)(4), and thus this regulatory
provision would still allow downstream parties to be deemed in
compliance and ease the demonstration burdens for gasoline-ethanol
blends that can be introduced into commerce under a CAA sec. 211(f)(4)
waiver or a substantially similar determination. We are updating our
existing regulations at 40 CFR 80.28 to allow for ethanol content up to
15 volume percent to utilize the ``deemed to comply'' provision. We
find this treatment appropriate because CAA sec. 211(h)(4) in its
entirety should be read to apply to gasoline-ethanol blends containing
at least 10 percent ethanol.
    The 1-psi waiver would be available to all fuel manufacturers
(i.e., refiners and importers) and downstream parties that produce,
distribute and sell E15 due to the sub sim determination in this
action. However, retailers that produce E15 via a blender pump would
still not comply with EPA fuels regulations at 40 CFR parts 79 and 80
unless they make the E15 solely from DFE and certified gasoline (or
CBOB). E15 produced at blender pumps could also continue to exceed even
an increased RVP limit of 10.0 psi.\192\ For further discussion of our
fuels' regulations and blender pumps, see the RTC document, available
in the docket for this action.
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    \192\ We note that for E15 produced at blender pumps using E85
made with natural gas liquids, use of the deemed to comply provision
to demonstrate compliance would not be available. This is because
the RVP of natural gas liquids can be as high as 15.0 psi and even a
small amount of natural gas liquids could cause the gasoline portion
of the blend to not comply with the applicable RVP limitations
established under CAA sec. 211(h), which is required under CAA sec.
211(h)(4)(A) to be deemed in compliance. Parties that make E15 at a
blender pump using E85 made with previously certified gasoline can
take advantage of the ``deemed to comply'' provision and associated
affirmative defense at 40 CFR 80.28 if all applicable requirements
in 80.28 are met.
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D. Regulatory Amendments

    This action finalizes technical amendments that would effectuate
our interpretation to allow the 1-psi waiver for E15 during the summer
under CAA sec. 211(h)(4) and our interpretation that E15 is sub sim
under CAA sec. 211(f) for MY2001 and newer light-duty vehicles. We are
therefore taking these actions under both CAA sec. 211(f) and 211(h).
1. Modification of Regulations
    First, we are modifying and removing volatility controls associated
with our prior interpretation of CAA sec. 211(h)(4). These controls,
found in 40 CFR 80.27, place limitations on the RVP of gasoline-ethanol
blends at specific concentrations. Given that the primary effect of our
proposed interpretation of CAA sec. 211(h)(4) would expand the
``special treatment for gasoline-ethanol blends'' to fuel blends
containing 9-15 percent ethanol, we are modifying both: (1) Regulations
extending the 1-psi waiver from gasoline containing 9-10 percent
ethanol to gasoline containing 9-15 percent ethanol at 40 CFR 80.27;
and (2) related defense provisions in 40 CFR 80.28.
    In public comments, some commenters suggested that EPA remove the
upper bound for ethanol content in 40 CFR 80.27 to be consistent with
our new interpretation of CAA sec. 211(h)(4). In particular, they
suggested that the regulation should provide the 1-psi waiver for any
gasoline-ethanol blend containing at least 10 percent ethanol, or for
any gasoline-ethanol blend containing at least 10 percent ethanol that
has a waiver under 211(f)(4) or is ``substantially similar.'' In
promulgating these regulations, we have determined that CAA sec.
211(h)(4) provides the lower bound for ethanol content, and CAA sec.
211(f) provides the upper bound. We do not find that it would be
appropriate to codify in our regulations no upper bound, as the
limitations on introduction into commerce under CAA sec. 211(f) are an
important mechanism to protect the emissions controls of motor vehicles
and nonroad products. Additionally, it would be inappropriate to allow
any gasoline-ethanol blend that contains ten volume percent ethanol the
1-psi waiver without consideration in a rulemaking process.
    Second, we are removing and modifying provisions in the MMR that
were imposed to effectuate the prior 1-psi waiver interpretation under
CAA sec. 211(h)(4). Subsequent to the grant of the CAA sec. 211(f)(4)
partial waivers for E15, we adopted regulations under CAA sec. 211(c)
to ensure that E15 would not be used in certain vehicles and engines
for which the waivers did not apply and to effectuate our
interpretation of 211(h)(4) at that time. To do so, in addition to the
conditions on the waivers that applied to fuel manufacturers, we
promulgated regulations to ensure that those same conditions were
enforceable on downstream parties. No changes were made to the RVP
regulations at 40 CFR 80.27 as a direct result of our interpretation
under CAA sec. 211(h)(4) that the 1-psi waiver did not extend to
gasoline-ethanol blends with an ethanol concentration greater than 10
percent. Additional regulations on parties that distribute E15 were put
in place at 40 CFR 80.1504(f) and (g) (placing prohibitions on the
commingling of E10

and E15), and 40 CFR 80.1503 (placing PTD requirements on E15). These
regulations were put in place in order to ensure that the RVP of E15
did not exceed 9.0 psi in accordance with our interpretation of CAA
sec. 211(h)(4) at the time. However, since our new interpretation of
CAA sec. 211(h)(4) increases the RVP allowance to 10.0 psi, these
provisions are no longer necessary. Additionally, because the RVP of
E15 will be approximately the same as E10 if produced from the same
blendstock, we do not anticipate adverse emissions impacts from
providing E15 the 1-psi waiver. Given that we are interpreting CAA sec.
211(h)(4) to extend to gasoline-ethanol blends of up to 15 percent
ethanol, the prohibition on the commingling of E15 and E10 is no longer
necessary.
    Finally, we are removing the PTD requirements related to the 1-psi
waiver at 40 CFR 80.1503. In 40 CFR part 80, subpart N, we included PTD
language designed to help ensure that E15 that did not receive the 1-
psi waiver would be segregated from E10 that did receive the 1-psi
waiver. Since we are allowing the 1-psi waiver for E15, we no longer
need these PTD requirements. However, parties that produce and
distribute gasoline-ethanol blended fuels would still be required to
identify ethanol concentrations on PTDs as specified in 40 CFR 80.27
and 40 CFR 80.1503.
2. Status of Misfueling Mitigation Rule Regulations
    All other E15 misfueling mitigation provisions in 40 CFR part 80,
subpart N, remain unchanged. In the MMR, we promulgated regulations
under CAA sec. 211(c)(1), which prohibit the use of E15 in MY2000 and
older motor vehicles, nonroad vehicles, engines, and equipment
(including motorcycles, and heavy-duty motor vehicles). CAA sec.
211(c)(1) gives EPA authority to ``control or prohibit the manufacture,
introduction into commerce, offering for sale, or sale'' of any fuel or
fuel additive (A) whose emission products, in the judgment of the
Administrator, cause or contribute to air pollution ``which may be
reasonably anticipated to endanger public health or welfare'' or (B)
whose emission products ``will impair to a significant degree the
performance of any emission control device or system which is in
general use, or which the Administrator finds has been developed to a
point where in a reasonable time it would be in general use'' were the
fuel control or prohibition adopted. We promulgated the MMR based on
our assessment that E15 would significantly impair the emission control
systems used in MY2000 and older light-duty motor vehicles, heavy-duty
gasoline engines and vehicles, highway and off-highway motorcycles, and
all nonroad products supporting our action under CAA sec. 211(c)(1)(B).
This led to our conclusion that under CAA sec. 211(c)(1)(A), E15 use in
these particular vehicles, engines, and non-road products would likely
result in increased VOC, CO, and NOX emissions.\193\ The
regulatory changes to 40 CFR part 80, subparts B and N in this action
are solely related to our proposed interpretation to allow the 1-psi
waiver for E15 under CAA sec. 211(h)(4) and CAA sec. 211(f). This
action does not change the basis of our CAA sec. 211(c)(1)(A) and (B)
finding in the MMR that prohibits E15 from use in MY2000 and older
light-duty motor vehicles, heavy-duty gasoline engines and vehicles,
highway and off-highway motorcycles, and all nonroad products. This
action also does not modify the misfueling mitigation measures
promulgated in the MMR.
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    \193\ 76 FR 44422 (July 25, 2011).
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3. Waiver Applicability
    As discussed in the proposal, we interpret CAA sec. 211(f) as
applying the waiver conditions to fuel and fuel additive manufacturers
as defined in 40 CFR 79.2. Therefore, the regulatory amendments
promulgated in this rulemaking apply to downstream parties, such as
oxygenate blenders, who are not fuel or fuel additive
manufacturers.\194\ Accordingly, so long as downstream parties, such as
oxygenate blenders, are only utilizing CBOB and denatured fuel ethanol
to create E15, these parties can apply the 1-psi waiver and thus can
blend and sell E15 at 10.0 psi.
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    \194\ Those fuel and fuel additive manufacturers would continue
to be subject to the CAA sec. 211(f)(4) E15 partial waivers
conditions, including the 9.0 psi RVP limitation. Therefore, in the
absence of a sub sim interpretative rule finding that E15 is sub
sim, we intend for the CAA sec. 211(f)(4) waiver to remain in
effect.
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    We received comment on this mechanism for providing E15 the 1-psi
waiver, and respond to those comments in the RTC document, available in
the docket for this action. This interpretation of the applicability of
the CAA sec. 211(f)(4) waiver conditions, in conjunction with our new
interpretation of CAA sec. 211(h)(4), is an independent basis from the
CAA sec. 211(f)(1) sub sim interpretation for the regulatory amendments
finalized in this rulemaking.
    We also find that, should fuel and fuel and additive manufacturers
choose to introduce E15 into commerce under the CAA sec. 211(f)(4)
waiver, these parties would continue to be subject to the 9.0 psi RVP
limit in the waiver conditions for E15. Downstream parties that only
add oxygenate in an allowable amount (i.e., as allowed under the CAA
sec. 211(f)(4) waivers) are not fuel and fuel additive manufacturers,
and thus would not need to meet the 9.0 psi waiver condition.

E. Expected Impact of This Rule on E15 Use

    We do not believe that providing E15 with the 1-psi waiver will
substantially change the current trend in E15 use. E15 can currently be
sold legally for use in MY2001 and newer light-duty motor vehicles in
the United States under the 211(f)(4) waivers. It has been 9 years
since EPA first granted the E15 211(f)(4) partial waivers; retailers
currently offer E15 at roughly just 1 percent of retail stations as
discussed in Section II.A.2. We expect that this slow adoption of E15
would continue even if we did not provide E15 the 1-psi waiver.
However, we also do not expect this action to change the rate of growth
appreciably. We believe that providing E15 with the 1-psi waiver will
not result in a significant expansion of E15 offered at retail
stations. This is due to the fact there are several hurdles,
independent of EPA's fuels regulations, that inhibit the expansion of
E15 into retail markets.
    The chief hurdle to the introduction of E15 at additional retail
stations is the requirement under 40 CFR 280.32 that retailers must
demonstrate that underground storage tank (UST) systems are compatible
with fuels stored at retail stations. Several commenters from the
gasoline marketing and retail industry highlighted concerns over
demonstrating compatibility of E15 with UST systems that have slowed
the adoption of E15. Demonstrating compatibility can be especially
difficult for some retailers as the full useful life of some UST system
components can be up to 30 years and documentation of all of the
various components often no longer exists, particularly when retail
stations often change ownership several times during this time period.
    Commenters also noted that a majority of retailers are small
businesses that would need to make substantial investments to ensure
the compatibility of UST systems and fuel dispensers with E15, which
can cost up to hundreds of thousands of dollars per station depending
on station configuration and what part of the UST system needs
upgrading.\195\ As

commenters noted, the best opportunity to upgrade retail infrastructure
is when it is time to turn over the UST system or fuel dispensers. As
commenters noted, since less than 3 percent of retail stations turn
over UST systems per year, this limits the opportunities for new E15
offerings.
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    \195\ See ``Analysis of the Potential Use of Biofuels toward the
Renewable Fuel Standard in 2014,'' available at https://ethanolrfa.org/wp-content/uploads/2015/09/Informa_Potential_Use_of_Biofuels_toward_RFS_20141.pdf.
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    Furthermore, not all retail stations that turn over their UST
systems are going to offer E15. Much of the introduction of E15 to date
has been in the Midwestern states, where blending incentives and
investments in retail infrastructure have been present.\196\ While some
retailers in states outside the Midwest have begun offering E15, it has
mainly been limited to retail stations with blender pumps. Therefore,
we would expect far fewer than 3 percent of retail stations nationwide
to turn over to E15 compatible UST systems annually. Historically, as
there are less than 2,000 stations offering E15 nationwide and E15 has
been a legal fuel for nine years, this translates to about a 0.1
percent increase in the number of retail stations offering E15 each
year. We expect a comparable trend to continue.
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    \196\ For example, the State of Iowa provides biofuels tax
credits for E15, see https://www.agmrc.org/renewable-energy/renewable-energy-climate-change-report/renewable-energy-climate-change-report/may-2017-report/overview-of-iowa-biofuel-tax-credits-and-ethanol-blends-sales-e10-e15-e20-and-e85. Additionally, USDA
provided grants under its Biofuel Infrastructure Partnership
program; see https://www.fsa.usda.gov/programs-and-services/energy-programs/bip/index.
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    Another hurdle to E15 market penetration highlighted by some
commenters is a lack of consumer demand or consumer acceptance. These
commenters noted that retailers will not limit their customer base and
therefore will continue to make E10 available for vehicles, engines,
and equipment that are not allowed to use E15.\197\ For the foreseeable
future, millions of MY2000 and older light-duty vehicles and hundreds
of millions of nonroad vehicles, engines, and equipment will continue
to be in use, and retailers will need to provide consumers with
suitable fuels for these products. Given this continued demand for E10
and the practicality of offering fuels that are only usable in certain
segments of the national fleet, many retailers have decided to offer
E10 which is usable in the entire fleet rather than offering both E10
and E15. Additionally, as several commenters noted, consumers are not
requesting that stations offer E15 instead of E10 and some consumers
have questions over the use of E15 in their vehicles and engines (even
when allowed to use E15 under the CAA). Some commenters noted that it
has only been in the last few years (not 2001) that most automakers
have begun to state in owner's manuals that E15 use is acceptable, and
several large auto manufacturers still include language in their
owner's manuals warning against E15 use; almost all owner's manuals for
nonroad products warn against E15 use.\198\ While we have evaluated
whether E15 is sub sim to Tier 3 E10 certification fuel, we do not have
authority under the CAA to impact what manufacturers put in their
owner's manuals or how they implement their general warranties. The
disparity between what vehicles and engines we have approved for E15
use under our 211(f) authority and which fuels manufacturers
recommended using in owner's manuals can lead to confusion and lack of
consumer acceptance of E15. This lack of consumer acceptance and demand
has resulted in E15 stations being primarily located in the Midwestern
states. As long as there is some uncertainty over whether vehicles,
engines, and equipment can and should use E15, these commenters argue,
retailers will be hesitant to offer E15. We believe that these
comments, primarily submitted by marketers and retailers of gasoline,
are accurate and we believe these hurdles all factor into our
projection that this action is unlikely to appreciably impact E15
market penetration.
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    \197\ In certain situations, such as limited USTs or pump
infrastructure, retailers are unable to make both E10 and E15
available. In these situations, commenters suggested that retailers
would chose to make E10 available rather than E15.
    \198\ See ``Head Like a Hole,'' available at http://www.fuelsinstitute.org/Media/The-Commute/Head-Like-a-Hole.
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    E15 also faces an economic challenge to market growth, even with
the 1-psi RVP waiver. Since the fuel distribution system will for the
foreseeable future only be capable of distributing BOBs designed for
E10, refiners will be unable to take advantage of the increased octane
value offered by 5 percent more ethanol in the gasoline they produce.
It is this octane value of ethanol that in recent years has been a key
factor in enabling ethanol to compete favorably with gasoline. Rarely
has ethanol been cheaper than gasoline on an energy equivalent
basis.\199\ As a consequence, there is seldom a meaningful economic
driver to produce and distribute E15 compared to E10, especially given
the service station upgrade costs.
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    \199\ Ethanol price data from USDA is available at https://www.ers.usda.gov/data-products/us-bioenergy-statistics/us-bioenergy-statistics/#Prices.
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    A final factor that presents a hurdle to E15 expansion is that E15
made at blender pumps often is done so inconsistently with EPA's
regulatory requirements. As discussed in the proposal, E15 made at
blender pumps is often made with certified E10 (or CBOB) and E85 (made
with denatured fuel ethanol and uncertified hydrocarbon blendstocks,
i.e., natural gas liquids).\200\ While data is limited, we believe that
approximately 50 percent of stations offering E15 make E15 in this
manner. The potential to violate EPA's regulatory requirements has
resulted in many parties choosing not to offer E15 until EPA provides a
legal pathway to make E15 at blender pumps. As mentioned in the
proposal, we had previously proposed requirements on E85 used to make
E15 at blender pumps that would both assure that the E15 met EPA's fuel
quality standards and provide a cost-effective compliance mechanism for
the retailers operating blender pumps to demonstrate compliance.\201\
Since we have not finalized those requirements or addressed the
technical challenges raised in public comments, we expect regulatory
uncertainty regarding E15 made at blender pumps to further inhibit E15
expansion.
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    \200\ See 84 FR 10595 (March 21, 2019).
    \201\ See 81 FR 80862-80864 (November 16, 2016).
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    As another example of these hurdles, E15 has not expanded
significantly into RFG areas, where the RVP of E15 has not been limited
by the 1-psi waiver. RFG represents over 30 percent of the gasoline in
the United States and refiners of RFG must comply with the summertime
RFG VOC performance standards, which effectively require refiners to
account for the increase in RVP that results from adding ethanol into
RFG. The result of this is that oxygenate blenders have been able to
produce E15 using the same RBOB as E10 in the summer since EPA granted
the first E15 waiver 9 years ago. However, according to the E15
compliance and RFG surveys, only five RFG areas (Chicago, Milwaukee,
St. Louis, Washington DC, and Dallas) out of 26 RFG areas have had any
E15 marketed in those areas and even in those areas, E15 has only been
offered in a limited number of stations.\202\ We

believe this lack of expansion of E15 in RFG areas is primarily a
result of the various hurdles discussed in this section, and we expect
similar results in conventional areas as a response to this action to
allow the 1-psi waiver for E15.
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    \202\ According to the RFG and E15 surveys, only 78 retail
stations in RFG areas are registered to sell E15. This is out of
22,287 retail stations in all RFG areas or 0.35 percent of RFG
stations. This is substantially lower than the national rate of
around 1.13 percent of retail stations nationally. This difference
in number, despite E15 not being limited by the 1-psi waiver in RFG
areas in the summer, is likely a result of the factors discussed in
this section. RFG areas tend to be in major metropolitan areas which
may have higher costs to install retail infrastructure compatible
with E15. This further illustrates how some of the hurdles to E15
introduction will not be addressed by providing E15 with the 1-psi
waiver.
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    Because this action does not change the rate of UST system and fuel
dispenser turnover, increase consumer demand or acceptance for E15,
ensure greater economic value for E15, or resolve the regulatory issues
associated with producing E15 at blender pumps; we do not believe
providing E15 the 1-psi waiver will result in a substantial expansion
of E15 being offered at new retail locations.
    Several commenters suggested that this action would result in
significant impacts on air quality or have a significant economic
impact. These commenters typically assume that every vehicle, engine,
and piece of equipment in country will begin using E15 and that if the
entire national fleet moved from E10 to E15 use substantial increases
in regulated pollutants, widespread degradation of air quality, or
necessitate billions of dollars of investments on the part of small
businesses to offer E15 as a result. As previously mentioned, we do not
expect that allowing E15 to receive the 1-psi waiver would result in
widespread E15 use. This action does not require that any party make,
distribute, sell, or use E15. As such, this action also does not
address the hurdles to entry of E15. Based on the experience of E15 in
areas that can already use E15 year-round (i.e., RFG areas), it is