Fuel type \a\                       specific net energy content,     mass fraction, wCref \b\
                                                        EmfuelCref, (MJ/kgC) \b\
----------------------------------------------------------------------------------------------------------------
Diesel fuel......................................                           49.3112                       0.874
Gasoline.........................................                           50.4742                       0.846
Natural Gas......................................                           66.2910                       0.750
LPG..............................................                           56.5218                       0.820
Dimethyl Ether...................................                           55.3886                       0.521
High-level ethanol-gasoline blends...............                           50.3211                       0.576
----------------------------------------------------------------------------------------------------------------
\a\ For fuels that are not listed, you must ask us to approve reference fuel properties.
\b\ For multi-fuel streams, such as natural gas with diesel fuel pilot injection, use good engineering judgment
  to determine blended values for EmfuelCref and wCref using the values in this table.

    (c) Your official emission result for each pollutant equals your
calculated brake-specific emission rate multiplied by all applicable
adjustment factors, other than the deterioration factor.

0
114. Revise Sec.  1036.535 to read as follows:

Sec.  1036.535  Determining steady-state engine fuel maps and fuel
consumption at idle.

    This section describes how to determine an engine's steady-state
fuel map and fuel consumption at idle for model year 2021 and later
vehicles. Vehicle manufacturers may need these values to demonstrate
compliance with emission standards under 40 CFR part 1037 as described
in Sec.  1036.510.
    (a) General test provisions. Perform fuel mapping using the
procedure described in paragraph (b) of this section to establish
measured fuel-consumption rates at a range of engine speed and load
settings. Measure fuel consumption at idle using the procedure
described in paragraph (c) of this section. If you perform cycle-
average mapping for highway cruise cycles as described in Sec.
1036.540, omit mapping under paragraph (b) of the section and instead
perform mapping as described in paragraph (d) of this section. Use
these measured fuel-consumption values to declare fuel-consumption
rates for certification as described in paragraph (e) of this section.
    (1) Map the engine's torque curve and declare engine idle speed as
described in Sec.  1036.503(c)(1) and (3), and perform emission
measurements as described in 40 CFR 1065.501 and 1065.530 for discrete-
mode steady-state testing. This section uses engine parameters and
variables that are consistent with 40 CFR part 1065.
    (2) Measure NOX emissions for each specified sampling
period in g/s. You

may perform these measurements using a NOX emission-
measurement system that meets the requirements of 40 CFR part 1065,
subpart J. Include these measured NOX values any time you
report to us your fuel consumption values from testing under this
section. If a system malfunction prevents you from measuring
NOX emissions during a test under this section but the test
otherwise gives valid results, you may consider this a valid test and
omit the NOX emission measurements; however, we may require
you to repeat the test if we determine that you inappropriately voided
the test with respect to NOX emission measurement.
    (b) Steady-state fuel mapping. Determine fuel-consumption rates for
each engine configuration over a series of steady-state engine
operating points consisting of pairs of speed and torque points as
described in this paragraph (b). You may use shared data across an
engine platform to the extent that the fuel-consumption rates remain
valid. For example, if you test a high-output configuration and create
a different configuration that uses the same fueling strategy but
limits the engine operation to be a subset of that from the high-output
configuration, you may use the fuel-consumption rates for the reduced
number of mapped points for the low-output configuration, as long as
the narrower map includes at least 70 points. Perform fuel mapping as
follows:
    (1) Generate the sequence of steady-state engine operating points
as follows:
    (i) Determine the required steady-state engine operating points as
follows:
    (A) For engines with an adjustable warm idle speed setpoint, select
the following speed setpoints: Minimum warm idle speed,
fnidlemin, the highest speed above maximum power at which
70% of maximum power occurs, nhi, and eight (or more)
equally spaced points between fnidlemin and nhi.
(See 40 CFR 1065.610(c)). For engines without an adjustable warm idle
speed replace minimum warm idle speed with warm idle speed,
fnidle.
    (B) Select the following torque setpoints at each of the selected
speed setpoints: Zero (T = 0), maximum mapped torque,
Tmax mapped, and eight (or more) equally spaced points
between T = 0 and Tmax mapped. For each of the selected
speed setpoints, replace any torque setpoints that are above the mapped
torque at the selected speed setpoint, Tmax, minus 5 percent
of Tmax mapped, with one test point at Tmax.
    (ii) Select any additional (optional) steady-state engine operating
points consistent with good engineering judgment. For example you may
select additional points when linear interpolation between the defined
points is not a reasonable assumption for determining fuel consumption
from the engine. For each additional speed setpoint, increments between
torque setpoints must be no larger than one-ninth of
Tmax,mapped and we recommend including a torque setpoint of
Tmax. If you select a maximum torque setpoint less than
Tmax, use good engineering judgment to select your maximum
torque setpoint to avoid unrepresentative data. Note that if the test
points were added for the child rating, they should still be reported
in the parent fuel map. We will select at least as many points as you.
    (iii) Set the run order for all of the steady-state engine
operating points (both required and optional) as described in this
paragraph (b)(1)(iii). Arrange the list of steady-state engine
operating points such that the resulting list of paired speed and
torque setpoints begins with the highest speed setpoint and highest
torque setpoint followed by decreasing torque setpoints at the highest
speed setpoint. This will be followed by the next lowest speed setpoint
and the highest torque setpoint at that speed setpoint continuing
through all the steady-state engine operating points and ending with
the lowest speed (fnidlemin) and torque setpoint (T = 0).
The following figure provides an example of this array of points and
run order.

[GRAPHIC] [TIFF OMITTED] TR29JN21.034

    (iv) The steady-state engine operating points that have the highest
torque setpoint for a given speed setpoint are optional reentry points
into the steady-state-fuel-mapping sequence, should you need to pause
or interrupt the sequence during testing.
    (v) The steady-state engine operating points that have the lowest
torque setpoint for a given speed setpoint are optional exit points
from the steady-state-fuel-mapping sequence, should you need to pause
or interrupt the sequence during testing.
    (2) If the engine has an adjustable warm idle speed setpoint, set
it to its minimum value, fnidlemin.
    (3) During each test interval, control speed within 1%
of nhi and engine torque within 5% of
Tmax mapped except for the following cases where both
setpoints cannot be achieved because the steady-state engine operating
point is near an engine operating boundary:
    (i) For steady-state engine operating points that cannot be
achieved and the operator demand stabilizes at minimum; control the
dynamometer so it gives priority to follow the torque setpoint and let
the engine govern the speed (see 40 CFR 1065.512(b)(1)). In this case,
the tolerance on speed control in paragraph (b)(3) of this section does
not apply and engine torque is controlled to within 25
N[middot]m.
    (ii) For steady-state engine operating points that cannot be
achieved and the operator demand stabilizes at maximum and the speed
setpoint is below 90% of nhi; control the dynamometer so it
gives priority to follow the speed setpoint and let the engine govern
the torque (see 40 CFR 1065.512(b)(2)). In this case, the tolerance on
torque control given in paragraph (b)(3) of this section does not
apply.
    (iii) For steady-state engine operating points that cannot be
achieved and the operator demand stabilizes at maximum and the speed
setpoint is at or above 90% of nhi; control the dynamometer
so it gives priority to follow the torque setpoint and let the engine
govern the speed (see 40 CFR 1065.512(b)(1)). In this case, the
tolerance on speed control given in paragraph (b)(3) of this section
does not apply.
    (iv) For the steady-state engine operating points at the minimum
speed setpoint and maximum torque setpoint, you may select a
dynamometer control mode that gives priority to speed and an engine
control mode that gives priority to torque. In this case, if the
operator demand stabilizes at minimum or maximum, the tolerance on
torque control in paragraph (b)(3) of this section does not apply.
    (4) You may select the appropriate dynamometer and engine control
modes in real-time or at any time prior based on various factors
including the operating setpoint location relative to an engine
operating boundary. Warm-up the engine as described in 40 CFR
1065.510(b)(2).
    (5) Within 60 seconds after concluding the warm-up, linearly ramp
the speed and torque setpoints over 5 seconds to the first steady-state
engine operating point from paragraph (b)(1) of this section.
    (6) Operate the engine at the steady-state engine operating point
for (70 1) seconds, and then start the test interval and
record measurements using one of the following methods. You must also
measure and report NOX emissions over each test interval as
described in paragraph (a)(2) of this section. If you use redundant
systems for the determination of fuel consumption, for example
combining measurements of

dilute and raw emissions when generating your map, follow the
requirements of 40 CFR 1065.201(d).
    (i) Indirect measurement of fuel flow. Record speed and torque and
measure emissions and other inputs needed to run the chemical balance
in 40 CFR 1065.655(c) for a (30 1) second test interval;
determine the corresponding mean values for the test interval. For
dilute sampling of emissions, in addition to the background measurement
provisions described in 40 CFR 1065.140 you may do the following:
    (A) If you use batch sampling to measure background emissions, you
may sample periodically into the bag over the course of multiple test
intervals and read them as allowed in paragraph (b)(7)(i) of this
section. If you use this paragraph (b)(6)(i)(A), you must apply the
same background readings to correct emissions from each of the
applicable test intervals.
    (B) You may determine background emissions by sampling from the
dilution air during the non-test interval periods in the test sequence,
including pauses allowed in paragraph (b)(7)(i) of this section. If you
use this paragraph (b)(6)(i)(B), you must allow sufficient time for
stabilization of the background measurement; followed by an averaging
period of at least 30 seconds. Use the average of the most recent pre-
test interval and the next post-test interval background readings to
correct each test interval. The most recent pre-test interval
background reading must be taken no greater than 30 minutes prior to
the start of the first applicable test interval and the next post-test
interval background reading must be taken no later than 30 minutes
after the end of the last applicable test interval. Background readings
must be taken prior to the test interval for each reentry point and
after the test interval for each exit point or more frequently.
    (ii) Direct measurement of fuel flow. Record speed and torque and
measure fuel consumption with a fuel flow meter for a (30 1) second test interval; determine the corresponding mean values
for the test interval.
    (7) After completing the test interval described in paragraph
(b)(6) of this section, linearly ramp the speed and torque setpoints
over 5 seconds to the next steady-state engine operating point.
    (i) You may pause the steady-state-fuel-mapping sequence at any of
the reentry points (as noted in paragraph (b)(1)(iv) of this section)
to calibrate emission-measurement instrumentation; to read and evacuate
background bag samples collected over the course of multiple test
intervals; or to sample the dilution air for background emissions. This
paragraph (b)(7)(i) allows you to spend more than the 70 seconds noted
in paragraph (b)(6) of this section.
    (ii) If an infrequent regeneration event occurs, interrupt the
steady-state-fuel-mapping sequence and allow the regeneration event to
finish. You may continue to operate at the steady-state engine
operating point where the event began or, using good engineering
judgment, you may transition to another operating condition to reduce
the regeneration event duration. You may complete any post-test
interval activities to validate test intervals prior to the most recent
reentry point. Once the regeneration event is finished, linearly ramp
the speed and torque setpoints over 5 seconds to the most recent
reentry point described in paragraph (b)(1)(iv) of this section, and
restart the steady-state-fuel-mapping sequence by repeating the steps
in paragraphs (b)(6) and (7) of this section for all the remaining
steady-state engine operating points. Operate at the reentry point for
longer than the 70 seconds in paragraph (b)(6), as needed, to bring the
aftertreatment to representative thermal conditions. Void all test
intervals in the steady-state-fuel-mapping sequence beginning with the
reentry point and ending with the steady-state engine operating point
where the regeneration event began.
    (iii) You may interrupt the steady-state-fuel-mapping sequence
after any of the exit points described in paragraph (b)(1)(v) of this
section. To restart the steady-state-fuel-mapping sequence; begin with
paragraph (b)(4) of this section and continue with paragraph (b)(5) of
this section, except that the steady-state engine operating point is
the next reentry point, not the first operating point from paragraph
(b)(1) of this section. Follow paragraphs (b)(6) and (7) of this
section until all remaining steady-state engine operating points are
tested.
    (iv) If the steady-state-fuel-mapping sequence is interrupted due
test equipment or engine malfunction, void all test intervals in the
steady-state-fuel-mapping sequence beginning with the most recent
reentry point as described in paragraph (b)(1)(iv) of this section.
Complete any post-test interval activities to validate test intervals
prior to the most recent reentry point. Correct the malfunction and
restart the steady-state-fuel-mapping sequence as described in
paragraph (b)(7)(iii) of this section.
    (v) If any steady-state engine test interval is voided, void all
test intervals in the steady-state-fuel-mapping sequence beginning with
the most recent reentry point as described in paragraph (b)(1)(iv) of
this section and ending with the next exit point as described in
paragraph (b)(1)(v) of this section. Rerun that segment of the steady-
state-fuel-mapping sequence. If multiple test intervals are voided in
multiple speed setpoints, you may exclude the speed setpoints where all
of the test intervals were valid from the rerun sequence. Rerun the
steady-state-fuel-mapping sequence as described in paragraph
(b)(7)(iii) of this section.
    (8) If you determine fuel-consumption rates using emission
measurements from the raw or diluted exhaust, calculate the mean fuel
mass flow rate, mifuel, for each point in the fuel map using
the following equation:
[GRAPHIC] [TIFF OMITTED] TR29JN21.035

Where:

mifuel = mean fuel mass flow rate for a given fuel map
setpoint, expressed to at least the nearest 0.001 g/s.
MC = molar mass of carbon.
wCmeas = carbon mass fraction of fuel (or mixture of test
fuels) as determined in 40 CFR 1065.655(d), except that you may not
use the default properties in Table 1 of 40 CFR 1065.655 to
determine [alpha], [beta], and wC for liquid fuels. You
may not account for the contribution to [alpha], [beta], [gamma],
and [delta] of diesel exhaust fluid or other non-fuel fluids
injected into the exhaust.
niexh = the mean raw exhaust molar flow rate from which
you measured emissions according to 40 CFR 1065.655.

xCcombdry = the mean concentration of carbon from fuel
and any injected fluids in the exhaust per mole of dry exhaust as
determined in 40 CFR 1065.655(c).
xH2Oexhdry = the mean concentration of H2O in
exhaust per mole of dry exhaust as determined in 40 CFR 1065.655(c).
miCO2DEF = the mean CO2 mass emission rate
resulting from diesel exhaust fluid decomposition as determined in
paragraph (b)(9) of this section. If your engine does not use diesel
exhaust fluid, or if you choose not to perform this correction, set
miCO2DEF equal to 0.
MCO2 = molar mass of carbon dioxide.

Example:

MC = 12.0107 g/mol
wCmeas = 0.869
niexh = 25.534 mol/s
xCcombdry = 0.002805 mol/mol
xH2Oexhdry = 0.0353 mol/mol
miCO2DEF = 0.0726 g/s
MCO2 = 44.0095 g/mol
[GRAPHIC] [TIFF OMITTED] TR29JN21.036

    (9) If you determine fuel-consumption rates using emission
measurements with engines that utilize diesel exhaust fluid for
NOX control, correct for the mean CO2 mass
emissions resulting from diesel exhaust fluid decomposition at each
fuel map setpoint using the following equation:
[GRAPHIC] [TIFF OMITTED] TR29JN21.037

Where:

miDEF = the mean mass flow rate of injected urea solution
diesel exhaust fluid for a given sampling period, determined
directly from the electronic control module, or measured separately,
consistent with good engineering judgment.
MCO2 = molar mass of carbon dioxide.
wCH4N2O = mass fraction of urea in diesel exhaust fluid
aqueous solution. Note that the subscript ``CH4N2O'' refers to urea
as a pure compound and the subscript ``DEF'' refers to the aqueous
urea diesel exhaust fluid as a solution of urea in water. You may
use a default value of 32.5% or use good engineering judgment to
determine this value based on measurement.
MCH4N2O = molar mass of urea.

Example:

miDEF = 0. 304 g/s
MCO2 = 44.0095 g/mol
wCH4N2O = 32.5% = 0.325
MCH4N2O = 60.05526 g/mol
[GRAPHIC] [TIFF OMITTED] TR29JN21.038

    (c) Fuel consumption at idle. Determine fuel-consumption rates for
engines certified for installation in vocational vehicles for each
engine configuration over a series of engine-idle operating points
consisting of pairs of speed and torque points as described in this
paragraph (c). You may use shared data across engine configurations,
consistent with good engineering judgment. Perform measurements as
follows:
    (1) Determine the required engine-idle operating points as follows:
    (i) Select the following two speed setpoints:
    (A) Engines with an adjustable warm idle speed setpoint: Minimum
warm idle speed, fnidlemin, and the maximum warm idle speed,
fnidlemax.
    (B) Engines without an adjustable warm idle speed setpoint: Warm
idle speed (with zero torque on the primary output shaft),
fnidle, and 1.15 times fnidle.
    (ii) Select the following two torque setpoints at each of the
selected speed setpoints: 0 and 100 N[middot]m.
    (iii) You may run these four engine-idle operating points in any
order.
    (2) Control speed and torque as follows:
    (i) Engines with an adjustable warm idle speed setpoint. For the
warm-up in paragraph (c)(3) of this section and the transition in
paragraph (c)(4) of this section control both speed and torque. At any
time prior to reaching the next engine-idle operating point, set the
engine's adjustable warm idle speed setpoint to the speed setpoint of
the next engine-idle operating point in the sequence. This may be done
before or during the warm-up or during the transition. Near the end of
the transition period control speed and torque as described in
paragraph (b)(3)(i) of this section. Once the transition is complete;
set the operator demand to minimum to allow the engine governor to
control speed; and control torque with the dynamometer as described in
paragraph (b)(3) of this section.
    (ii) Engines without an adjustable warm idle speed setpoint.
Control speed and torque with operator demand and the dynamometer for
the engine-idle operating points at the higher speed setpoint as
described in paragraph (b)(3) of this section. Both the speed and
torque tolerances apply for these points because they are not near the
engine's operating boundary and are achievable. Control speed and
torque for the engine-idle operating points at the lower speed setpoint
as described in paragraph (c)(2)(i) of this section except for setting
the engine's adjustable warm idle speed setpoint.
    (3) Warm-up the engine as described in 40 CFR 1065.510(b)(2).
    (4) After concluding the warm-up procedure, linearly ramp the speed
and torque setpoints over 20 seconds to operate the engine at the next
engine-idle operating point from paragraph (c)(1) of this section.
    (5) Operate the engine at the engine-idle operating point for (180
1) seconds, and then start the test interval and record
measurements using one of the following methods. You must also measure
and report NOX emissions over each test interval as
described in paragraph (a)(2) of this section. If you use redundant
systems for the determination of fuel consumption, for example
combining measurements of dilute and raw emissions when generating your
map, follow the requirements of 40 CFR 1065.201(d).
    (i) Indirect measurement of fuel flow. Record speed and torque and
measure emissions and other inputs needed to run the chemical balance
in 40 CFR 1065.655(c) for a (600 1) second test interval;
determine the corresponding mean values for the test interval. We

will use an average of indirect measurement of fuel flow with dilute
sampling and direct sampling. For dilute sampling of emissions, measure
background according to the provisions described in 40 CFR 1065.140,
but read the background as described in paragraph (c)(7)(i) of this
section. If you use batch sampling to measure background emissions, you
may sample periodically into the bag over the course of multiple test
intervals and read them as allowed in paragraph (b)(7)(i) of this
section. If you use this paragraph (c)(5)(i), you must apply the same
background readings to correct emissions from each of the applicable
test intervals. Note that the minimum dilution ratio requirements for
PM sampling in 40 CFR 1065.140(e)(2) do not apply. We recommend
minimizing the CVS flow rate to minimize errors due to background
correction consistent with good engineering judgment and operational
constraints such as minimum flow rate for good mixing.
    (ii) Direct measurement of fuel flow. Record speed and torque and
measure fuel consumption with a fuel flow meter for a (600 1) second test interval; determine the corresponding mean values
for the test interval.
    (6) After completing the test interval described in paragraph
(c)(5) of this section, repeat the steps in paragraphs (c)(3) through
(5) of this section for all the remaining engine-idle operating points.
After completing the test interval on the last engine-idle operating
point, the fuel-consumption-at-idle sequence is complete.
    (7) The following provisions apply for interruptions in the fuel-
consumption-at-idle sequence in a way that is intended to produce
results equivalent to running the sequence without interruption:
    (i) You may pause the fuel-consumption-at-idle sequence after each
test interval to calibrate emission-measurement instrumentation and to
read and evacuate background bag samples collected over the course of a
single test interval. This paragraph (c)(7)(i) allows you to shut-down
the engine or to spend more time at the speed/torque idle setpoint
after completing the test interval before transitioning to the step in
paragraph (c)(3) of this section.
    (ii) If an infrequent regeneration event occurs, interrupt the
fuel-consumption-at-idle sequence and allow the regeneration event to
finish. You may continue to operate at the engine-idle operating point
where the event began or, using good engineering judgment, you may
transition to another operating condition to reduce the regeneration
event duration. If the event occurs during a test interval, void that
test interval. Once the regeneration event is finished, restart the
fuel-consumption-at-idle sequence by repeating the steps in paragraphs
(c)(3) through (5) of this section for all the remaining engine-idle
operating points.
    (iii) You may interrupt the fuel-consumption-at-idle sequence after
any of the test intervals. Restart the fuel-consumption-at-idle
sequence by repeating the steps in paragraphs (c)(3) through (5) of
this section for all the remaining engine-idle operating points.
    (iv) If the fuel-consumption-at-idle sequence is interrupted due to
test equipment or engine malfunction, correct the malfunction and
restart the fuel-consumption-at-idle sequence by repeating the steps in
paragraphs (c)(3) through (5) of this section for all the remaining
engine-idle operating points. If the malfunction occurred during a test
interval, void that test interval.
    (v) If any idle test intervals are voided, repeat the steps in
paragraphs (c)(3) through (5) of this section for each of the voided
engine-idle operating points.
    (8) Correct the measured or calculated mean fuel mass flow rate,
mifuel at each of the engine-idle operating points to
account for mass-specific net energy content as described in paragraph
(b)(13) of this section.
    (d) Steady-state fuel maps used for cycle-average fuel mapping of
the cruise cycles. Determine fuel-consumption rates for each engine
configuration over a series of steady-state engine operating points
near idle as described in this paragraph (d). You may use shared data
across an engine platform to the extent that the fuel-consumption rates
remain valid.
    (1) Perform steady-state fuel mapping as described in paragraph (b)
of this section with the following exceptions:
    (i) All the required steady-state engine operating points as
described in paragraph (b)(1)(i) of this section are optional.
    (ii) Select speed setpoints to cover the range of idle speeds
expected as follows:
    (A) The minimum number of speed setpoints is two.
    (B) For engines with an adjustable warm idle speed setpoint, the
minimum speed setpoint must be equal to the minimum warm idle speed,
fnidlemin, and the maximum speed setpoint must be equal to
or greater than the maximum warm idle speed, fnidlemax. The
minimum speed setpoint for engines without an adjustable warm idle
speed setpoint, must be equal to the warm idle speed (with zero torque
on the primary output shaft), fnidle, and the maximum speed
setpoint must be equal to or greater than 1.15 times the warm idle
speed, fnidle.
    (iii) Select torque setpoints at each speed setpoint to cover the
range of idle torques expected as follows:
    (A) The minimum number of torque setpoints at each speed setpoint
is three. Note that you must meet the minimum torque spacing
requirements described in paragraph (b)(1)(ii) of this section.
    (B) The minimum torque setpoint at each speed setpoint is zero.
    (C) The maximum torque setpoint at each speed setpoint must be
greater than or equal to the estimated maximum torque at warm idle (in-
drive) conditions, Tidlemaxest, using the following
equation. For engines with an adjustable warm idle speed setpoint,
evaluate Tidlemaxest at the maximum warm idle speed,
fnidlemax. For engines without an adjustable warm idle speed
setpoint, use the warm idle speed (with zero torque on the primary
output shaft), fnidle.
[GRAPHIC] [TIFF OMITTED] TR29JN21.039

Where:

Tfnstall = the maximum engine torque at
fnstall.
fnidle = the applicable engine idle speed as described in
this paragraph (d).
fnstall = the stall speed of the torque converter; use
fntest or 2250 r/min, whichever is lower.
Pacc = accessory power for the vehicle class; use 1500 W
for Vocational Light HDV, 2500 W for Vocational Medium HDV, and 3500
W for Tractors and Vocational Heavy HDV.

Example:

Tfnstall = 1870 N[middot]m
fntest = 1740.8 r/min = 182.30 rad/s
fnstall = 1740.8 r/min = 182.30 rad/s
fnidle = 700 r/min = 73.30 rad/s
Pacc = 1500 W
[GRAPHIC] [TIFF OMITTED] TR29JN21.040

    (2) Remove the points from the default map that are below 115% of
the maximum speed and 115% of the maximum torque of the boundaries of
the points measured in paragraph (d)(1) of this section.
    (3) Add the points measured in paragraph (d)(1) of this section.
    (e) Carbon balance verification. The provisions related to carbon
balance verification in Sec.  1036.543 apply to test intervals in this
section.
    (f) Correction for net energy content. Correct the measured or
calculated mean fuel mass flow rate, mifuel at each engine
operating condition as specified in paragraphs (b), (c), and (d) of
this section to a mass-specific net energy content of a reference fuel
using the following equation:
[GRAPHIC] [TIFF OMITTED] TR29JN21.041

Where:

Emfuelmeas = the mass-specific net energy content of the
test fuel as determined in Sec.  1036.530(b)(1).
EmfuelCref = the reference value of carbon-mass-specific
net energy content for the appropriate fuel. Use the values shown in
Table 1 of Sec.  1036.530 for the designated fuel types, or values
we approve for other fuel types.
wCref = the reference value of carbon mass fraction for
the test fuel as shown in Table 1 of Sec.  1036.530 for the
designated fuels. For other fuels, use the reference carbon mass
fraction of diesel fuel for engines subject to compression-ignition
standards, and use the reference carbon mass fraction of gasoline
for engines subject to spark-ignition standards.

Example:

mifuel = 0.933 g/s
Emfuelmeas = 42.7984 MJ/kgC
EmfuelCref = 49.3112 MJ/kgC
wCref = 0.874
[GRAPHIC] [TIFF OMITTED] TR29JN21.042

    (g) Measured vs. declared fuel-consumption rates. Select fuel-
consumption rates in g/s to characterize the engine's fuel maps. These
declared values may not be lower than any corresponding measured values
determined in paragraphs (b) through (d) of this section. This includes
if you use multiple measurement methods as allowed in paragraph (b)(7)
of this section. You may select any value that is at or above the
corresponding measured value. These declared fuel-consumption rates,
which serve as emission standards under Sec.  1036.108, are the values
that vehicle manufacturers will use for certification under 40 CFR part
1037. Note that production engines are subject to GEM cycle-weighted
limits as described in Sec.  1036.301. If you perform the carbon
balance error verification in Sec.  1036.543, for each fuel map data
point:
    (1) If you pass the [isin]rC verification, you must
declare fuel-consumption rates no lower than the average of the direct
and indirect fuel measurements.
    (2) If you pass either the [isin]aC verification or
[isin]aCrate verification and fail the [isin]rC
verification, you must declare fuel-consumption rates no lower than the
indirect fuel measurement.
    (3) If you don't pass the [isin]rC, [isin]aC,
and [isin]aCrate verifications, you must declare fuel-
consumption rates no lower than the highest rate for the direct and
indirect fuel measurements.
    (h) EPA measured fuel-consumption rates. If we pass the carbon mass
relative error for a test interval ([isin]rC) verification,
the official fuel-consumption rate result will be the average of the
direct and indirect fuel measurements. If we pass either the carbon
mass absolute error for a test interval ([isin]aC)
verification or carbon mass rate absolute error for a test interval
([isin]aCrate) verification and fail the [isin]rC
verification, the official fuel-consumption rate result will be the
indirect fuel measurement.

0
115. Revise Sec.  1036.540 to read as follows:

Sec.  1036.540  Determining cycle-average engine fuel maps.

    (a) Overview. This section describes how to determine an engine's
cycle-average fuel maps for model year 2021 and later vehicles with
transient cycles. This section may also apply for highway cruise cycles
as described in Sec.  1036.510. Vehicle manufacturers may need cycle-
average fuel maps for transient duty cycles, highway cruise cycles, or
both to demonstrate compliance with emission standards under 40 CFR
part 1037. Generating cycle-average engine fuel maps consists of the
following steps:
    (1) Determine the engine's torque maps as described in Sec.
1036.510(a).
    (2) Determine the engine's steady-state fuel map and fuel
consumption at idle as described in Sec.  1036.535.
    (3) Simulate several different vehicle configurations using GEM
(see 40 CFR 1037.520) to create new engine duty cycles, as described in
paragraph (c) of this section. The transient vehicle duty cycles for
this simulation are in 40 CFR part 1037, appendix I; the highway cruise
cycles with grade are in 40 CFR part 1037, appendix IV. Note that GEM
simulation relies on vehicle service classes as described in 40 CFR
1037.140.
    (4) Test the engines using the new duty cycles to determine fuel
consumption, cycle work, and average vehicle speed as described in
paragraph (d) of this section and establish GEM inputs for those
parameters for further vehicle simulations as described in paragraph
(e) of this section.
    (b) General test provisions. The following provisions apply for
testing under this section:
    (1) To perform fuel mapping under this section for hybrid engines,
make sure the engine and its hybrid features are appropriately
configured to represent the hybrid features in your testing.
    (2) Measure NOX emissions for each specified sampling
period in grams. You may perform these measurements using a
NOX emission-measurement system that meets the requirements
of 40 CFR part 1065, subpart J. Include these measured NOX
values any time you report to us your fuel consumption values from
testing under this section. If a system malfunction prevents you from
measuring NOX emissions during a test under this section but
the test otherwise gives valid results, you may consider this a valid
test and omit the NOX emission measurements; however, we may
require you to repeat the test if we determine that you inappropriately
voided the test with respect to NOX emission measurement.
    (3) This section uses engine parameters and variables that are
consistent with 40 CFR part 1065.
    (4) For variable-speed gaseous-fueled engines with a single-point
fuel injection system, apply all of the following statistical criteria
to validate the transient duty cycle in 40 CFR part 1037, appendix I:

                                           Table 1 to Sec.   1036.540
----------------------------------------------------------------------------------------------------------------
              Parameter                         Speed                    Torque                   Power
----------------------------------------------------------------------------------------------------------------
Slope, a1............................  0.950 <= a1 <=1.030....  0.830 <= a1 <=1.030....  0.830 <= a1 <=1.030.
Absolute value of intercept,           <=10% of warm idle.....  <=3% of maximum mapped   <=2% of maximum mapped
 [bond]a0[bond].                                                 torque.                  power.

Standard error of the estimate, SEE..  <=5% of maximum test     <=15% of maximum mapped  <=15% of maximum mapped
                                        speed.                   torque.                  power.
Coefficient of determination, r2.....  >=0.970................  >=0.700................  >=0.750.
----------------------------------------------------------------------------------------------------------------

    (c) Create engine duty cycles. Use GEM to simulate several
different vehicle configurations to create transient and highway cruise
engine duty cycles corresponding to each vehicle configuration, as
follows:
    (1) Set up GEM to simulate vehicle operation based on your engine's
torque maps, steady-state fuel maps, engine minimum warm-idle speed and
fuel consumption at idle as described in paragraphs (a)(1) and (2) of
this section, as well as 40 CFR 1065.405(b). For engines without an
adjustable warm idle speed replace minimum warm idle speed with warm
idle speed, fnidle.
    (2) Set up GEM with transmission parameters for different vehicle
service classes and vehicle duty cycles as described in Table 2 of this
section. For automatic transmissions set neutral idle to ``Y'' in the
vehicle file. These values are based on automatic or automated manual
transmissions, but they apply for all transmission types.
[GRAPHIC] [TIFF OMITTED] TR29JN21.043

[GRAPHIC] [TIFF OMITTED] TR29JN21.044

Where:

fn[speed] = engine's angular speed as determined in
paragraph (c)(3)(ii) or (iii) of this section.
ktopgear = transmission gear ratio in the highest
available gear from Table 2 of this section (for powertrain testing
use actual top gear ratio).
vref = reference speed. Use 65 mi/hr for the transient
cycle and the 65 mi/hr highway cruise cycle, and use 55 mi/hr for
the 55 mi/hr highway cruise cycle.
[GRAPHIC] [TIFF OMITTED] TR29JN21.045

Example for a vocational Light HDV or vocational Medium HDV with a 6-
speed automatic transmission at B speed (Test 3 or 4 in Table 3 of this
section):

fnrefB = 1870 r/min = 31.17 r/s
kaB = 4.0
ktopgear = 0.61
vref = 65 mi/hr = 29.06 m/s
[GRAPHIC] [TIFF OMITTED] TR29JN21.046

    (ii) Test at least eight different vehicle configurations for
engines that will be installed in vocational Light HDV or vocational
Medium HDV using vehicles in Table 3 of this section. For example, if
your engines will be installed in vocational Medium HDV and vocational
Heavy HDV, you might select Tests 2, 4, 6, and 8 of Table 3 of this
section to represent vocational Medium HDV and Tests 2, 3, 4, 6, and 9
of Table 4 of this section to represent vocational Heavy HDV. You may
test your engine using additional vehicle configurations with different
ka and Crr values to represent a wider range of
in-use vehicle configurations. For all vehicle configurations set the
drive axle configuration to 4x2. For powertrain testing, set
Mrotating to 340 kg and Effaxle to 0.955 for all
vehicle configurations. Set the axle ratio, ka, and tire
size,
[GRAPHIC] [TIFF OMITTED] TR29JN21.047

for each vehicle configuration based on the corresponding designated
engine speed (fnrefA, fnrefB, fnrefC,
or fntest) at 65 mi/hr for the transient cycle and the 65
mi/hr highway cruise cycle, and at 55 mi/hr for the 55 mi/hr highway
cruise cycle. These vehicle speeds apply equally for engines subject to
spark-ignition standards. Use the following

settings specific to each vehicle configuration:
[GRAPHIC] [TIFF OMITTED] TR29JN21.048

    (iii) Test nine different vehicle configurations for engines that
will be installed in vocational Heavy HDV and for tractors that are not
heavy-haul tractors. Test six different vehicle configurations for
heavy-haul tractors. You may test your engines for additional
configurations with different ka, CdA, and
Crr values to represent a wider range of in-use vehicle
configurations. Set Crr to 6.9 for all nine defined vehicle
configurations. For class 7 and 8 vehicle configurations set the drive
axle configuration to 4x2 and 6x4 respectively. For powertrain testing,
set Effaxle to 0.955 for all vehicle configurations. Set the
axle ratio, ka, and tire size,
[GRAPHIC] [TIFF OMITTED] TR29JN21.049

for each vehicle configuration based on the corresponding designated
engine speed (B, fntest, or the minimum NTE exclusion speed
as determined in 40 CFR 86.1370(b)(1)) at 65 mi/hr for the transient
duty cycle and the 65 mi/hr highway cruise duty cycle, and at 55 mi/hr
for the 55 mi/hr highway cruise duty cycle. Use the settings specific
to each vehicle configuration as shown in Table 4 or Table 5 of this
section, as appropriate. Engines subject to testing under both Tables 4
and 5 of this section need not repeat overlapping vehicle
configurations, so complete fuel mapping requires testing 12 (not 15)
vehicle configurations for those engines. However, the preceding
sentence does not apply if you choose to create two separate maps from
the vehicle configurations defined in Tables 4 and 5 of this section.
Note that Mrotating is needed for powertrain testing but not
for engine testing. Tables 4 and 5 follow:

[GRAPHIC] [TIFF OMITTED] TR29JN21.050

[GRAPHIC] [TIFF OMITTED] TR29JN21.051

    (iv) If the engine will be installed in a combination of vehicles
defined in paragraphs (c)(3)(ii) and (iii) of this section, use good
engineering judgment to select at least nine vehicle configurations
from Tables 3 and 4 of this section that best represent the range of
vehicles your engine will be sold in. If there are not nine
representative configurations you must add vehicles, that you define,
to reach a total of at least nine vehicles. For example, if your
engines will be installed in vocational Medium HDV and vocational Heavy
HDV, select Tests 2, 4, 6 and 8 of Table 3 of this section to represent
Medium HDV and Tests 3, 6, and 9 of Table 4 of this section to
represent vocational Heavy HDV and add two more vehicles that you
define. You may test your engine using additional vehicle
configurations with different ka and Crr values
to represent a wider range of in-use vehicle configurations.
    (v) Use the defined values in Tables 2 through 5 of this section to
set up GEM with the correct regulatory subcategory and vehicle weight
reduction, if applicable, to achieve the target vehicle mass, M, for
each test.
    (4) Use the GEM output of instantaneous engine speed and engine
flywheel torque for each of the vehicle configurations to generate a 10
Hz transient duty cycle corresponding to each vehicle configuration
operating over each vehicle duty cycle.
    (d) Test the engine with GEM cycles. Test the engine over each of
the transient engine duty cycles generated in paragraph (c) of this
section as follows:
    (1) Determine the sequence of engine duty cycles (both required and
optional) for the cycle-average-fuel-mapping sequence as follows:
    (i) Sort the list of engine duty cycles into three separate groups
by vehicle duty cycle; transient vehicle duty cycle, 55 mi/hr highway
cruise duty cycle, and the 65 mi/hr highway cruise duty cycle.
    (ii) Within each group of engine duty cycles derived from the same
vehicle duty cycle, order the duty cycles as follows: Select the engine
duty cycle with the highest reference cycle work; followed by the cycle
with the lowest cycle work; followed by the cycle with next highest
cycle work; followed by the

cycle with the next lowest cycle work; until all the cycles are
selected.
    (iii) For each engine duty cycle, preconditioning cycles will be
needed to start the cycle-average-fuel-mapping sequence.
    (A) For the first and second cycle in each sequence, the two
preconditioning cycles are the first cycle in the sequence, the
transient vehicle duty cycle with the highest reference cycle work.
This cycle is run twice for preconditioning prior to starting the
sequence for either of the first two cycles.
    (B) For all other cycles, the two preconditioning cycles are the
previous two cycles in the sequence.
    (2) If the engine has an adjustable warm idle speed setpoint, set
it to its minimum value, fnidlemin.
    (3) During each test interval, control speed and torque to meet the
cycle validation criteria in 40 CFR 1065.514, except as noted in this
paragraph (d)(3). Note that 40 CFR part 1065 does not allow subsampling
of the 10 Hz GEM generated reference cycle. If the range of reference
speeds is less than 10 percent of the mean reference speed, you only
need to meet the standard error of the estimate in Table 2 of 40 CFR
1065.514 for the speed regression.
    (4) Warm-up the engine as described in 40 CFR 1065.510(b)(2).
    (5) Transition between duty cycles as follows:
    (i) For transient duty cycles, start the next cycle within 10
seconds after the conclusion of the preceding cycle. Note that this
paragraph (d)(5)(i) applies to transitioning from both the
preconditioning cycles and tests for record.
    (ii) For cruise cycles, linearly ramp to the next cycle over 5
seconds and stabilize for 15 seconds prior to starting the next cycle.
Note that this paragraph (d)(5)(ii) applies to transitioning from both
the preconditioning cycles and tests for record.
    (6) Operate the engine over the engine duty cycle and record
measurements using one of the methods described in paragraph (d)(6)(i)
or (ii) of this section. You must also measure and report
NOX emissions over each test interval as described in
paragraph (a)(2) of this section. If you use redundant systems for the
determination of fuel consumption, for example combining measurements
of dilute and raw emissions when generating your map, follow the
requirements of 40 CFR 1065.201(d).
    (i) Indirect measurement of fuel flow. Record speed and torque and
measure emissions and other inputs needed to run the chemical balance
in 40 CFR 1065.655(c) for the test interval defined by the first engine
duty cycle; determine the corresponding mean values for the test
interval. For dilute sampling of emissions, in addition to the
background measurement provisions described in 40 CFR 1065.140, you may
do the following:
    (A) Measure background as described in Sec.  1036.535(b)(7)(i)(A)
but read the background as described in paragraph (d)(9)(i) of this
section.
    (B) Measure background as described in Sec.  1036.535(b)(7)(i)(B)
but read the background as described in paragraph (d)(9)(i) of this
section.
    (ii) Direct measurement of fuel flow. Record speed and torque and
measure fuel consumption with a fuel flow meter for the test interval
defined by the first engine duty cycle; determine the corresponding
mean values for the test interval.
    (7) Repeat the steps in paragraph (d)(6) of this section for all
the remaining engine duty cycles.
    (8) Repeat the steps in paragraphs (d)(4) through (7) of this
section for all the applicable groups of duty cycles (e.g., transient
vehicle duty cycle, 55 mi/hr highway cruise duty cycle, and the 65 mi/
hr highway cruise duty cycle).
    (9) The following provisions apply for interruptions in the cycle-
average-fuel-mapping sequence in a way that is intended to produce
results equivalent to running the sequence without interruption:
    (i) You may pause the cycle-average-fuel-mapping sequence after
each test interval to calibrate emission-measurement instrumentation,
to read and evacuate background bag samples collected over the course
of multiple test intervals, or to sample the dilution air for
background emissions. This paragraph (d)(9)(i) requires you to shut-
down the engine during the pause. If the pause is longer than 30
minutes, restart the engine and restart the cycle-average-fuel-mapping
sequence at the step in paragraph (d)(4) of this section. Otherwise,
restart the engine and restart the cycle-average-fuel-mapping sequence
at the step in paragraph (d)(5) of this section.
    (ii) If an infrequent regeneration event occurs, interrupt the
cycle-average-fuel-mapping sequence and allow the regeneration event to
finish. You may continue to operate the engine over the engine duty
cycle where the event began or, using good engineering judgment, you
may transition to another operating condition to reduce the
regeneration event duration.
    (A) Determine which cycles in the sequence to void as follows:
    (1) If the regeneration event began during a test interval, the
cycle associated with that test interval must be voided.
    (2) If you used dilute sampling to measure emissions and you used
batch sampling to measure background emissions that were sampled
periodically into the bag over the course of multiple test intervals
and you are unable to read the background bag (e.g., sample volume too
small), void all cycles associated with that background bag.
    (3) If you used dilute sampling to measure emissions and you used
the option to sample periodically from the dilution air and you did not
meet all the requirements for this option as described in paragraph
(d)(6)(i)(B) of this section, void all cycles associated with those
background readings.
    (4) If the regeneration event began during a non-test-interval
period of the sequence and the provisions in paragraphs
(d)(9)(ii)(A)(2) and (3) of this section do not apply, you do not need
to void any cycles.
    (B) Determine the cycle to restart the sequence. Identify the cycle
associated with the last valid test interval. The next cycle in the
sequence is the cycle to be used to restart the sequence.
    (C) Once the regeneration event is finished, restart the sequence
at the cycle determined in paragraph (d)(9)(ii)(B) of this section
instead of the first cycle of the sequence. If the engine is not
already warm, restart the sequence at paragraph (d)(4) of this section.
Otherwise, restart at paragraph (d)(5) of this section.
    (iii) If the cycle-average-fuel-mapping sequence is interrupted due
to test equipment or engine malfunction, correct the malfunction and
follow the steps in paragraphs (d)(9)(ii)(A) through (C) of this
section to restart the sequence. Treat the detection of the malfunction
as the beginning of the regeneration event.
    (iv) If any test interval in the cycle-average-fuel-mapping
sequence is voided, you must rerun that test interval as described in
this paragraph (d)(9)(iv). You may rerun the whole sequence or any
contiguous part of the sequence. If you end up with multiple valid test
intervals for a given cycle, use the last valid test interval for
determining the cycle-average fuel map. If the engine has been shut-
down for more than 30 minutes or if it is not already warm, restart the
sequence at paragraph (d)(4) of this section. Otherwise, restart at
paragraph (d)(5) of this section. Repeat the steps in paragraphs (d)(6)
and (7) of this section until you complete the whole sequence or part
of the sequence.

The following examples illustrate possible scenarios for completing
only part of the sequence:
    (A) If you voided only the test interval associated with the fourth
cycle in the sequence, you may restart the sequence using the second
and third cycles as the preconditioning cycles and stop after
completing the test interval associated with the fourth cycle.
    (B) If you voided the test intervals associated with the fourth and
sixth cycles, you may restart the sequence using the second and third
cycles as the preconditioning cycles and stop after completing the test
interval associated with the sixth cycle. If the test interval
associated with the fifth cycle in this sequence was valid, it must be
used for determining the cycle-average fuel map instead of the original
one.
    (10) For plug-in hybrid engines, precondition the battery and then
complete all back-to-back tests for each vehicle configuration
according to 40 CFR 1066.501 before moving to the next vehicle
configuration.
    (11) You may send signals to the engine controller during the test,
such as current transmission gear and vehicle speed, if that allows
engine operation during the test to better represent in-use operation.
    (12) For hybrid powertrains with no plug-in capability, correct for
the net energy change of the energy storage device as described in 40
CFR 1066.501. For plug-in hybrid engines, follow 40 CFR 1066.501 to
determine End-of-Test for charge-depleting operation; to do this, you
must get our advance approval for a utility factor curve. We will
approve your utility factor curve if you can show that you created it
from sufficient in-use data of vehicles in the same application as the
vehicles in which the plug-in hybrid electric vehicle (PHEV) engine
will be installed.
    (13) Calculate the fuel mass flow rate, mfuel, for each
duty cycle using one of the following equations:
    (i) Determine fuel-consumption rates using emission measurements
from the raw or diluted exhaust, calculate the mass of fuel for each
duty cycle, mfuel[cycle], as follows:
    (A) For calculations that use continuous measurement of emissions
and continuous CO2 from urea, calculate
mfuel[cycle] using the following equation:
[GRAPHIC] [TIFF OMITTED] TR29JN21.052

Where:

MC = molar mass of carbon.
wCmeas = carbon mass fraction of fuel (or mixture of test
fuels) as determined in 40 CFR 1065.655(d), except that you may not
use the default properties in Table 1 of 40 CFR 1065.655 to
determine [alpha], [beta], and wC for liquid fuels.
i = an indexing variable that represents one recorded emission
value.
N = total number of measurements over the duty cycle.
nexh = exhaust molar flow rate from which you measured
emissions.
xCcombdry = amount of carbon from fuel and any injected
fluids in the exhaust per mole of dry exhaust as determined in 40
CFR 1065.655(c).
xH2Oexhdry = amount of H2O in exhaust per mole
of exhaust as determined in 40 CFR 1065.655(c).
[Delta]t = 1/frecord
MCO2 = molar mass of carbon dioxide.
mCO2DEFi = mass emission rate of CO2 resulting
from diesel exhaust fluid decomposition over the duty cycle as
determined from Sec.  1036.535(b)(7). If your engine does not
utilize diesel exhaust fluid for emission control, or if you choose
not to perform this correction, set mCO2DEFi equal to 0.

Example:

MC = 12.0107 g/mol
wCmeas = 0.867
N = 6680
nexh1 = 2.876 mol/s
nexh2 = 2.224 mol/s
xCcombdry1 = 2.61[middot]10-\3\ mol/mol
xCcombdry2 = 1.91[middot]10-\3\ mol/mol
xH2Oexh1 = 3.53[middot]10-\2\ mol/mol
xH2Oexh2 = 3.13[middot]10-\2\ mol/mol
frecord = 10 Hz
[Delta]t = 1/10 = 0.1 s
MCO2 = 44.0095 g/mol
mCO2DEF1 = 0.0726 g/s
mCO2DEF2 = 0.0751 g/s
BILLING CODE 6560-50-P

[GRAPHIC] [TIFF OMITTED] TR29JN21.053

BILLING CODE 6560-50-C
    (ii) Manufacturers may choose to measure fuel mass flow rate.
Calculate the mass of fuel for each duty cycle,
mfuel[cycle], as follows:
[GRAPHIC] [TIFF OMITTED] TR29JN21.054

Where:

i = an indexing variable that represents one recorded value.
N = total number of measurements over the duty cycle. For batch fuel
mass measurements, set N = 1.
mfueli = the fuel mass flow rate, for each point, i,
starting from i = 1.
[Delta]t = 1/frecord

frecord = the data recording frequency.

Example:

N = 6680
mfuel1 = 1.856 g/s
mfuel2 = 1.962 g/s
frecord = 10 Hz
[Delta]t = 1/10 = 0.1 s
mfueltransient = (1.856 + 1.962 + . . . +
mfuel6680) [middot] 0.1
mfueltransient = 111.95 g

    (14) The provisions related to carbon balance error verification in
Sec.  1036.543 apply to test intervals in this section.
    (15) Correct the measured or calculated fuel mass flow rate,
mfuel, for each test result to a mass-specific net energy
content of a reference fuel as described in Sec.  1036.535(e),
replacing with mifuel in Eq. 1036.535-4.
    (16) For engines designed for plug-in hybrid electric vehicles, the
mass of fuel for each cycle, mfuel[cycle], is the utility
factor-weighted fuel mass. This is done by calculating mfuel
for the full charge-depleting and charge-sustaining portions of the
test and weighting the results, using the following equation:
[GRAPHIC] [TIFF OMITTED] TR29JN21.055

Where:

mfuel[cycle],CD = total mass of fuel for all the tests in
the charge-depleting portion of the test.
UFD,CD = utility factor fraction at distance
DCD as determined by interpolating the approved utility
factor curve.
mfuel[cycle],CS = total mass of fuel for all the tests in
the charge-sustaining portion of the test.
[GRAPHIC] [TIFF OMITTED] TR29JN21.056

Where:

v = vehicle velocity at each time step. For tests completed under
this section, v is the vehicle velocity in the GEM duty-cycle file.
For tests under 40 CFR 1037.550, v is the vehicle velocity as
determined by Eq. 1037.550-1 of 40 CFR 1037.550. Note that this
should include complete and incomplete charge-depleting tests.

    (e) Determine GEM inputs. Use the results of engine testing in
paragraph (d) of this section to determine the GEM inputs for the
transient duty cycle and optionally for each of the highway cruise
cycles corresponding to each simulated vehicle configuration as
follows:
    (1) Your declared fuel mass consumption, mfuel[cycle].
Using the calculated fuel mass consumption values described in
paragraph (d) of this section, declare values using the method
described in Sec.  1036.535(g).
    (2) We will determine mfuel[cycle] values using the
method described in Sec.  1036.535(h).
    (3) Engine output speed per unit vehicle speed,
    [GRAPHIC] [TIFF OMITTED] TR29JN21.057

by taking the average engine speed measured during the engine test
while the vehicle is moving and dividing it by the average vehicle
speed provided by GEM. Note that the engine cycle created by GEM has a
flag to indicate when the vehicle is moving.
    (4) Positive work determined according to 40 CFR part 1065,
W[cycle], by using the engine speed and engine torque
measured during the engine test while the vehicle is moving. Note that
the engine cycle created by GEM has a flag to indicate when the vehicle
is moving.
    (5) The engine idle speed and torque, by taking the average engine
speed and torque measured during the engine test while the vehicle is
not moving. Note that the engine cycle created by GEM has a flag to
indicate when the vehicle is moving.
    (6) The following table illustrates the GEM data inputs
corresponding to the different vehicle configurations for a given duty
cycle:
[GRAPHIC] [TIFF OMITTED] TR29JN21.058

0
116. Add Sec.  1036.543 to read as follows:

Sec.  1036.543  Carbon balance error verification.

    A carbon balance error verification compares independent
assessments of the flow of carbon through the system (engine plus
aftertreatment). We will, and you may optionally, verify carbon balance
error according to 40 CFR 1065.543. This section applies to all test
intervals in Sec. Sec.  1036.535(b), (c), and (d) and 1036.540 and 40
CFR 1037.550.

0
117. Amend Sec.  1036.620 by revising paragraphs (a) and (b)(1)(iii) to
read as follows:

Sec.  1036.620  Alternate CO2 standards based on model year 2011
compression-ignition engines.

* * * * *
    (a) The standards of this section are determined from the measured
emission rate of the test engine of the applicable baseline 2011 engine
family or families as described in paragraphs (b) and (c) of this
section. Calculate the CO2 emission rate of the baseline
test engine using the same equations used for showing compliance with
the otherwise applicable standard. The alternate CO2
standard for light and medium heavy-duty vocational-certified engines
(certified for CO2 using the transient cycle) is equal to
the baseline emission rate multiplied by 0.975. The alternate
CO2 standard for tractor-certified engines (certified for
CO2 using the SET duty cycle) and all other heavy heavy-duty
engines is equal to the baseline emission rate multiplied by 0.970. The
in-use FEL for these engines is equal to the alternate standard
multiplied by 1.03.
    (b) * * *
    (1) * * *
    (iii) Calculate separate adjustments for emissions over the SET
duty cycle and the transient cycle.
* * * * *

0
118. Amend Sec.  1036.701 by revising paragraphs (i) and (j) to read as
follows:

Sec.  1036.701  General provisions.

* * * * *
    (i) Unless the regulations in this part explicitly allow it, you
may not calculate Phase 1 credits more than once for any emission
reduction. For example, if you generate Phase 1 CO2 emission
credits for a hybrid engine under this part for a given vehicle, no one
may generate CO2 emission credits for that same hybrid
engine and the associated vehicle under 40 CFR part 1037. However,
Phase 1 credits could be generated for identical vehicles using engines
that did not generate credits under this part.
    (j) Credits you generate with compression-ignition engines in 2020
and earlier model years may be used in model year 2021 and later as
follows:
    (1) For credit-generating engines certified to the tractor engine
standards in Sec.  1036.108, you may use credits calculated relative to
the tractor engine standards.
    (2) For credit-generating engines certified to the vocational
engine standards in Sec.  1036.108, you may optionally carry over
adjusted vocational credits from an averaging set, and you may use
credits calculated relative to the emission levels in the following
table:

   Table 1 of Sec.   1036.701--Emission Levels for Credit Calculation
------------------------------------------------------------------------
        Medium heavy-duty  engines            Heavy heavy-duty engines
------------------------------------------------------------------------
558 g/hp[middot]hr........................  525 g/hp[middot]hr.
------------------------------------------------------------------------

* * * * *

0
119. Amend Sec.  1036.705 by revising paragraphs (b)(2) and (5) to read
as follows:

Sec.  1036.705  Generating and calculating emission credits.

* * * * *
    (b) * * *
    (2) For tractor engines:

Emission credits (Mg) = (Std-FCL) [middot] (CF) [middot] (Volume)
[middot] (UL) [middot] (10-6)

Where:

Std = the emission standard, in g/hp-hr, that applies under subpart
B of this part for engines not participating in the ABT program of
this subpart (the ``otherwise applicable standard'').
FCL = the Family Certification Level for the engine family, in g/hp-
hr, measured over the SET duty cycle rounded to the same number of
decimal places as the emission standard.
CF = a transient cycle conversion factor (hp-hr/mile), calculated by
dividing the total (integrated) horsepower-hour over the duty cycle
(average of tractor-engine configurations weighted by their
production volumes) by 6.3 miles for engines subject to spark-
ignition standards and 6.5 miles for engines subject to compression-
ignition standards. This represents the average work performed by
tractor engines in the family over the mileage represented by
operation over the duty cycle. Note that this calculation requires
you to use the transient cycle conversion factor even for engines
certified to standards based on the SET duty cycle.
Volume = the number of tractor engines eligible to participate in
the averaging, banking, and trading program within the given engine
family during the model year, as described in paragraph (c) of this
section.
UL = the useful life for the given engine family, in miles.
* * * * *
    (5) You may generate CO2 emission credits from a model
year 2021 or later medium heavy-duty engine family subject to spark-
ignition standards for exchanging with other engine families only if
the engines in the family are gasoline-fueled. You may generate
CO2 credits from non-gasoline engine families only for the
purpose of offsetting CH4 and/or N2O emissions
within the same engine family as described in paragraph (d) of this
section.
* * * * *

0
120. Amend Sec.  1036.801 by:
0
a. Revising the definitions for ``Auxiliary emission control device'',
``Heavy-duty vehicle'', and ``Hybrid''.
0
b. Adding definitions for ``Hybrid engine'', ``Hybrid powertrain'', and
``Mild hybrid'' in alphabetical order.
0
c. Revising the definition for ``Steady-state''.
    The revisions and additions read as follows:

Sec.  1036.801   Definitions.

* * * * *
    Auxiliary emission control device means any element of design that
senses temperature, motive speed, engine speed (r/min), transmission
gear, or any other parameter for the purpose of activating, modulating,
delaying, or deactivating the operation of any part of the emission
control system.
* * * * *
    Heavy-duty vehicle means any motor vehicle above 8,500 pounds GVWR.
An incomplete vehicle is also a heavy-duty vehicle if it has a curb
weight above 6,000 pounds or a basic vehicle frontal area greater than
45 square feet. Curb weight and basic vehicle frontal area have the
meaning given in 40 CFR 86.1803-01.
    Hybrid means an engine or powertrain that includes energy storage
features other than a conventional battery system or conventional
flywheel. Supplemental electrical batteries and hydraulic accumulators
are examples of hybrid energy storage systems. Note that certain
provisions in this part treat hybrid engines and hybrid powertrains
intended for vehicles that include regenerative braking different than
those intended for vehicles that do not include regenerative braking.
    Hybrid engine means a hybrid system with features for storing and
recovering energy that are integral to the engine or are otherwise
upstream of the vehicle's

transmission other than a conventional battery system or conventional
flywheel. Supplemental electrical batteries and hydraulic accumulators
are examples of hybrid energy storage systems. Examples of hybrids that
could be considered hybrid engines are P0, P1, and P2 hybrids where
hybrid features are connected to the front end of the engine, at the
crankshaft, or connected between the clutch and the transmission where
the clutch upstream of the hybrid feature is in addition to the
transmission clutch(s), respectively. Note other examples of systems
that qualify as hybrid engines are systems that recover kinetic energy
and use it to power an electric heater in the aftertreatment.
    Hybrid powertrain means a powertrain that includes energy storage
features other than a conventional battery system or conventional
flywheel. Supplemental electrical batteries and hydraulic accumulators
are examples of hybrid energy storage systems. Note other examples of
systems that qualify as hybrid powertrains are systems that recover
kinetic energy and use it to power an electric heater in the
aftertreatment.
* * * * *
    Mild hybrid means a hybrid engine or powertrain with regenerative
braking capability where the system recovers less than 20 percent of
the total braking energy over the transient cycle defined in appendix I
of 40 CFR part 1037.
* * * * *
    Steady-state has the meaning given in 40 CFR 1065.1001. This
includes fuel mapping and idle testing where engine speed and load are
held at a finite set of nominally constant values.
* * * * *

0
121. Amend Sec.  1036.805 by revising paragraphs (b) through (f) and
adding paragraph (g) to read as follows:

Sec.  1036.805  Symbols, abbreviations, and acronyms.

* * * * *
    (b) Symbols for quantities. This part uses the following symbols
and units of measure for various quantities:

                               Table 2 to Sec.   1036.805--Symbols for Quantities
----------------------------------------------------------------------------------------------------------------
                                                                                Unit in terms of SI
          Symbol                 Quantity                Unit               Unit symbol           base units
----------------------------------------------------------------------------------------------------------------
[alpha]..................  atomic hydrogen-to-   mole per mole.......  mol/mol.............  1.
                            carbon ratio.
[Agr]....................  Area................  square meter........  m2..................  m2.
[beta]...................  atomic oxygen-to-     mole per mole.......  mol/mol.............  1.
                            carbon ratio.
Cd[Agr]..................  drag area...........  meter squared.......  m2..................  m2.
Crr......................  coefficient of        kilogram per metric   kg/tonne............  10-3.
                            rolling resistance.   ton.
D........................  distance............  miles or meters.....  mi or m.............  m.
[egr]....................  efficiency..........
[isin]...................  Difference or error
                            quantity.
e........................  mass weighted         grams/ton-mile......  g/ton-mi............  g/kg-km.
                            emission result.
Eff......................  efficiency..........
Em.......................  mass-specific net     megajoules/kilogram.  MJ/kg...............  m2[middot]s-2.
                            energy content.
fn.......................  angular speed         revolutions per       r/min...............  [pi][middot]30[midd
                            (shaft).              minute.                                     ot]s-1.
g........................  gravitational         meters per second     m/s2................  m[middot]s-2.
                            acceleration.         squared.
i........................  indexing variable...
ka.......................  drive axle ratio....  ....................  ....................  1.
ktopgear.................  highest available
                            transmission gear.
m........................  Mass................  pound mass or         lbm or kg...........  kg.
                                                  kilogram.
M........................  molar mass..........  gram per mole.......  g/mol...............  10-
                                                                                3[middot]kg[middot
                                                                                ]mol-1.
M........................  vehicle mass........  kilogram............  kg..................  kg.
Mrotating................  inertial mass of      kilogram............  kg..................  kg.
                            rotating components.
N........................  total number in a
                            series.
P........................  Power...............  kilowatt............  kW..................  103[middot]m2[middo
                                                                                t]kg[middot]s-3.
[rho]....................  mass density........  kilogram per cubic    kg/m3...............  m-3[middot]kg.
                                                  meter.
r........................  tire radius.........  meter...............  m...................  m.
SEE......................  standard error of
                            the estimate.
[sigma]..................  standard deviation..
T........................  torque (moment of     newton meter........  N[middot]m..........  m2[middot]kg[middot
                            force).                                                           ]s-2.
t........................  Time................  second..............  s...................  s.
[Delta]t.................  time interval,        second..............  s...................  s.
                            period, 1/frequency.
UF.......................  utility factor......
v........................  Speed...............  miles per hour or     mi/hr or m/s........  m[middot]s-1.
                                                  meters per second.
W........................  Work................  kilowatt-hour.......  kW[middot]hr........  3.6[middot]m2[middo
                                                                                t]kg[middot]s-1.
wC.......................  carbon mass fraction  gram/gram...........  g/g.................  1.
wCH4N2O..................  urea mass fraction..  gram/gram...........  g/g.................  1.
x........................  amount of substance   mole per mole.......  mol/mol.............  1.
                            mole fraction.
xb.......................  brake energy
                            fraction.
xbl......................  brake energy limit..
----------------------------------------------------------------------------------------------------------------

    (c) Superscripts. This part uses the following superscripts for
modifying quantity symbols:

                Table 3 to Sec.   1036.805--Superscripts
------------------------------------------------------------------------
                Superscript                            Meaning
------------------------------------------------------------------------
overbar (such as y).......................  arithmetic mean.
overdot (such as y).......................  quantity per unit time.
------------------------------------------------------------------------

    (d) Subscripts. This part uses the following subscripts for
modifying quantity symbols:

                 Table 4 to Sec.   1036.805--Subscripts
------------------------------------------------------------------------
          Subscript                             Meaning
------------------------------------------------------------------------
65...........................  65 miles per hour.
A............................  A speed.
A............................  absolute (e.g., absolute difference or
                                error).
Acc..........................  accessory.
App..........................  approved.
Axle.........................  axle.
B............................  B speed.
C............................  C speed.
C............................  carbon mass.
Ccombdry.....................  carbon from fuel per mole of dry exhaust.
CD...........................  charge-depleting.
CO2DEF.......................  CO2 resulting from diesel exhaust fluid
                                decomposition.
comb.........................  combustion.
comp.........................  composite.
Cor..........................  corrected.
CS...........................  charge-sustaining.
Cycle........................  test cycle.
DEF..........................  diesel exhaust fluid.
engine.......................  engine.
Exh..........................  raw exhaust.
Front........................  frontal.
Fuel.........................  fuel.
H2Oexhaustdry................  H2O in exhaust per mole of exhaust.
Hi...........................  high.
I............................  an individual of a series.
Idle.........................  idle.
M............................  mass.
Max..........................  maximum.
mapped.......................  mapped.
Meas.........................  measured quantity.
Neg..........................  negative.
Pos..........................  positive.
R............................  relative (e.g., relative difference or
                                error).
Rate.........................  rate (divided by time).
Rated........................  rated.
record.......................  record.
Ref..........................  reference quantity.
speed........................  speed.
Stall........................  stall.
Test.........................  test.
Tire.........................  tire.
transient....................  transient.
[Mgr]........................  vector.
vehicle......................  vehicle.
------------------------------------------------------------------------

    (e) Other acronyms and abbreviations. This part uses the following
additional abbreviations and acronyms:

      Table 5 to Sec.   1036.805--Other Acronyms and Abbreviations
------------------------------------------------------------------------
           Acronym                              Meaning
------------------------------------------------------------------------
ABT..........................  averaging, banking, and trading.
AECD.........................  auxiliary emission control device.
ASTM.........................  American Society for Testing and
                                Materials.
BTU..........................  British thermal units.
CD...........................  charge-depleting.
CFR..........................  Code of Federal Regulations.
CI...........................  Compression-ignition.
COV..........................  coefficient of variation.
CS...........................  charge-sustaining.
DEF..........................  diesel exhaust fluid.
DF...........................  deterioration factor.
DOT..........................  Department of Transportation.
E85..........................  gasoline blend including nominally 85
                                percent denatured ethanol.
ECU..........................  Electronic Control Unit.
EPA..........................  Environmental Protection Agency.
FCL..........................  Family Certification Level.

FEL..........................  Family Emission Limit.
GEM..........................  Greenhouse gas Emissions Model.
g/hp-hr......................  grams per brake horsepower-hour.
GVWR.........................  gross vehicle weight rating.
HDV..........................  heavy-duty vehicle.
LPG..........................  liquefied petroleum gas.
NARA.........................  National Archives and Records
                                Administration.
NHTSA........................  National Highway Traffic Safety
                                Administration.
NTE..........................  not-to-exceed.
RESS.........................  rechargeable energy storage system.
RMC..........................  ramped-modal cycle.
SCR..........................  selective catalytic reduction.
SEE..........................  standard error of the estimate.
SET..........................  Supplemental Emission Test.
SI...........................  spark-ignition.
U.S..........................  United States.
U.S.C........................  United States Code.
------------------------------------------------------------------------

    (f) Constants. This part uses the following constants:

                  Table 6 to Sec.   1036.805--Constants
------------------------------------------------------------------------
       Symbol                Quantity                    Value
------------------------------------------------------------------------
g..................  gravitational constant.  9.80665 m[middot]s-2
------------------------------------------------------------------------

    (g) Prefixes. This part uses the following prefixes to define a
quantity:

                  Table 7 to Sec.   1036.805--Prefixes
------------------------------------------------------------------------
       Symbol                Quantity                    Value
------------------------------------------------------------------------
[micro]............  micro..................  10-6
m..................  milli..................  10-3
c..................  centi..................  10-2
k..................  kilo...................  103
M..................  mega...................  106
------------------------------------------------------------------------

0
122. Revise Sec.  1036.810 to read as follows:

Sec.  1036.810  Incorporation by reference.

    Certain material is incorporated by reference into this part with
the approval of the Director of the Federal Register under 5 U.S.C.
552(a) and 1 CFR part 51. To enforce any edition other than that
specified in this section, the Environmental Protection Agency must
publish a document in the Federal Register and the material must be
available to the public. All approved material is available for
inspection at U.S. EPA, Air and Radiation Docket and Information
Center, WJC West Building, Room 3334, 1301 Constitution Ave. NW,
Washington, DC 20460, www.epa.gov/dockets,<PHONE_NUMBER>, and is
available from the sources listed in this section. It is also available
for inspection at the National Archives and Records Administration
(NARA). For information on the availability of this material at NARA,
call<PHONE_NUMBER>, or go to www.archives.gov/federal-register/cfr/ibr-locations.html.
    (a) ASTM International, 100 Barr Harbor Drive, P.O. Box C700, West
Conshohocken, PA 19428-2959,<PHONE_NUMBER>, www.astm.org/.
    (1) ASTM D3588-98 (Reapproved 2017)e1, Standard Practice for
Calculating Heat Value, Compressibility Factor, and Relative Density of
Gaseous Fuels, approved April 1, 2017, (``ASTM D3588''), IBR approved
for Sec.  1036.530(b).
    (2) ASTM D4809-13, Standard Test Method for Heat of Combustion of
Liquid Hydrocarbon Fuels by Bomb Calorimeter (Precision Method),
approved May 1, 2013, (``ASTM D4809''), IBR approved for Sec.
1036.530(b).
    (b) National Institute of Standards and Technology, 100 Bureau
Drive, Stop 1070, Gaithersburg, MD 20899-1070,<PHONE_NUMBER>, or
www.nist.gov.
    (1) NIST Special Publication 811, Guide for the Use of the
International System of Units (SI), 2008 Edition, March 2008, IBR
approved for Sec.  1036.805.
    (2) [Reserved]

0
123. Amend Sec.  1036.825 by revising paragraph (a) to read as follows:

Sec.  1036.825  Reporting and recordkeeping requirements.

    (a) This part includes various requirements to submit and record
data or other information. Unless we specify otherwise, store required
records in any format and on any media and keep them readily available
for eight years after you send an associated application for
certification, or eight years after you generate the data if they do
not support an application for certification. We may review these
records at any time. You must promptly give us organized, written
records in English if we ask for them. We may require you to submit
written records in an electronic format.
* * * * *

Appendix I to Part 1036 [Redesignated as Appendix C to Part 1036]

0
124. Redesignate appendix I to part 1036 as appendix C to part 1036.

0
125. Add appendix A to part 1036 to read as follows:

Appendix A to Part 1036--Summary of Previous Emission Standards

    The following standards, which EPA originally adopted under 40
CFR part 85 or 86, apply to compression-ignition engines produced
before model year 2007 and to spark-ignition engines produced before
model year 2008:
    (a) Smoke. Smoke standards applied for compression-ignition
engines based on opacity measurement using the test procedures in 40
CFR part 86, subpart I, as follows:
    (1) Engines were subject to the following smoke standards for
model years 1970 through 1973:
    (i) 40 percent during the engine acceleration mode.
    (ii) 20 percent during the engine lugging mode.
    (2) The smoke standards in 40 CFR 86.11 started to apply in
model year 1974.
    (b) Idle CO. A standard of 0.5 percent of exhaust gas flow at
curb idle applied through model year 2016 to the following engines:
    (1) Spark-ignition engines with aftertreatment starting in model
year 1987. This standard applied only for gasoline-fueled engines
through model year 1997. Starting in model year 1998, the same
standard applied for engines fueled by methanol, LPG, and natural
gas. The idle CO standard no longer applied for engines certified to
meet onboard diagnostic requirements starting in model year 2005.
    (2) Methanol-fueled compression-ignition engines starting in
model year 1990. This

standard also applied for natural gas and LPG engines starting in
model year 1997. The idle CO standard no longer applied for engines
certified to meet onboard diagnostic requirements starting in model
year 2007.
    (c) Crankcase emissions. The requirement to design engines to
prevent crankcase emissions applied starting with the following
engines:
    (1) Spark-ignition engines starting in model year 1968. This
standard applied only for gasoline-fueled engines through model year
1989, and applied for spark-ignition engines using other fuels
starting in model year 1990.
    (2) Naturally aspirated diesel-fueled engines starting in model
year 1985.
    (3) Methanol-fueled compression-ignition engines starting in
model year 1990.
    (4) Naturally aspirated gaseous-fueled engines starting in model
year 1997, and all other gaseous-fueled engines starting in 1998.
    (d) Early steady-state standards. The following criteria
standards applied to heavy-duty engines based on steady-state
measurement procedures:

               Table 1 to Appendix A--Early Steady-State Emission Standards for Heavy-Duty Engines
----------------------------------------------------------------------------------------------------------------
                                                                               Pollutant
           Model year                    Fuel        -----------------------------------------------------------
                                                              HC               NOX + HC               CO
----------------------------------------------------------------------------------------------------------------
1970-1973.......................  gasoline..........  275 ppm...........  ..................  1.5 volume
                                                                                percent.
1974-1978.......................  gasoline and        ..................  16 g/hp[middot]hr.  40 g/hp[middot]hr.
                                   diesel.
1979-1984 a.....................  gasoline and        ..................  5 g/hp[middot]hr    25 g/hp[middot]hr.
                                   diesel.                                 for diesel, 5.0 g/
                                                                           hp[middot]hr for
                                                                           gasoline.
----------------------------------------------------------------------------------------------------------------
a An optional NOX + HC standard of 10 g/hp[middot]hr applied in 1979 through 1984 in conjunction with a separate
  HC standard of 1.5 g/hp[middot]hr.

    (e) Transient emission standards for spark-ignition engines. The
following criteria standards applied for spark-ignition engines
based on transient measurement using the test procedures in 40 CFR
part 86, subpart N. Starting in model year 1991, manufacturers could
generate or use emission credits for NOX and
NOX + NMHC standards. Table 2 to this appendix follows:

               Table 2 to Appendix A--Transient Emission Standards for Spark-Ignition Engines a b
----------------------------------------------------------------------------------------------------------------
                                                                    Pollutant (g/hp[middot]hr)
                   Model year                    ---------------------------------------------------------------
                                                        HC              CO              NOX         NOX + NMHC
----------------------------------------------------------------------------------------------------------------
1985-1987.......................................             1.1            14.4            10.6  ..............
1988-1990.......................................             1.1            14.4             6.0  ..............
1991-1997.......................................             1.1            14.4             5.0  ..............
1998-2004 \c\...................................             1.1            14.4             4.0  ..............
2005-2007.......................................  ..............            14.4  ..............         \d\ 1.0
----------------------------------------------------------------------------------------------------------------
\a\ Standards applied only for gasoline-fueled engines through model year 1989. Standards started to apply for
  methanol in model year 1990, and for LPG and natural gas in model year 1998.
\b\ Engines intended for installation only in heavy-duty vehicles above 14,000 pounds GVWR were subject to an HC
  standard of 1.9 g/hp[middot]hr for model years 1987 through 2004, and a CO standard of 37.1 g/hp[middot]hr for
  model years 1987 through 2007. In addition, for model years 1987 through 2007, up to 5 percent of a
  manufacturer's sales of engines intended for installation in heavy-duty vehicles at or below 14,000 pounds
  GVWR could be certified to the alternative HC and CO standards.
\c\ For natural gas engines in model years 1998 through 2004, the NOX standard was 5.0 g/hp[middot]hr; the HC
  standards were 1.7 g/hp[middot]hr for engines intended for installation only in vehicles above 14,000 pounds
  GVWR, and 0.9 g/hp[middot]hr for other engines.
\d\ Manufacturers could delay the 1.0 g/hp[middot]hr NOX + NMHC standard until model year 2008 by meeting an
  alternate NOX + NMHC standard of 1.5 g/hp[middot]hr applied for model years 2004 through 2007.

    (f) Transient emission standards for compression-ignition
engines. The following criteria standards applied for compression-
ignition engines based on transient measurement using the test
procedures in 40 CFR part 86, subpart N. Starting in model year
1991, manufacturers could generate or use emission credits for
NOX, NOX + NMHC, and PM standards. Table 3 to
this appendix follows:

             Table 3 to Appendix A--Transient Emission Standards for Compression-Ignition Engines a
----------------------------------------------------------------------------------------------------------------
                                                           Pollutant (g/hp[middot]hr)
          Model year           ---------------------------------------------------------------------------------
                                      HC              CO              NOX         NOX + NMHC           PM
----------------------------------------------------------------------------------------------------------------
1985-1987.....................             1.3            15.5            10.7  ..............  ................
1988-1989.....................             1.3            15.5            10.7  ..............  0.60.
1990..........................             1.3            15.5             6.0  ..............  0.60.
1991-1992.....................             1.3            15.5             5.0  ..............  0.25.
1993..........................             1.3            15.5             5.0  ..............  0.25 truck, 0.10
                                                                                bus.
1994-1995.....................             1.3            15.5             5.0  ..............  0.10 truck, 0.07
                                                                                urban bus.
1996-1997.....................             1.3            15.5             5.0  ..............  0.10 truck, 0.05
                                                                                urban bus.\b\
1998-2003.....................             1.3            15.5             4.0  ..............  0.10 truck, 0.05
                                                                                urban bus.\b\
2004-2006.....................  ..............            15.5  ..............         \c\ 2.4  0.10 truck, 0.05
                                                                                urban bus.\b\
----------------------------------------------------------------------------------------------------------------
\a\ Standards applied only for diesel-fueled engines through model year 1989. Standards started to apply for
  methanol in model year 1990, and for LPG and natural gas in model year 1997. An alternate HC standard of 1.2 g/
  hp[middot]hr applied for natural gas engines for model years 1997 through 2003.
\b\ The in-use PM standard for urban bus engines in model years 1996 through 2006 was 0.07 g/hp[middot]hr.

\c\ An optional NOX + NMHC standard of 2.5 g/hp[middot]hr applied in 2004 through 2006 in conjunction with a
  separate NMHC standard of 0.5 g/hp[middot]hr.

0
126. Add appendix B to part 1036 to read as follows:

Appendix B to Part 1036--Transient Duty Cycles

    (a) This appendix specifies transient duty cycles for the engine
and powertrain testing described in Sec.  1036.510, as follows:
    (1) The transient duty cycle for testing engines involves a
schedule of normalized engine speed and torque values.
    (2) The transient duty cycles for powertrain testing involves a
schedule of vehicle speeds and road grade. Determine road grade at
each point based on the peak rated power of the powertrain system,
Prated, determined in Sec.  1036.527 and road grade
coefficients using the following equation:
[GRAPHIC] [TIFF OMITTED] TR29JN21.059

    (b) The following transient duty cycle applies for spark-
ignition engines and powertrains:
BILLING CODE 6560-50-P
[GRAPHIC] [TIFF OMITTED] TR29JN21.060

[GRAPHIC] [TIFF OMITTED] TR29JN21.061

[GRAPHIC] [TIFF OMITTED] TR29JN21.062

[GRAPHIC] [TIFF OMITTED] TR29JN21.063

[GRAPHIC] [TIFF OMITTED] TR29JN21.064

[GRAPHIC] [TIFF OMITTED] TR29JN21.065

[GRAPHIC] [TIFF OMITTED] TR29JN21.066

[GRAPHIC] [TIFF OMITTED] TR29JN21.067

[GRAPHIC] [TIFF OMITTED] TR29JN21.068

[GRAPHIC] [TIFF OMITTED] TR29JN21.069

[GRAPHIC] [TIFF OMITTED] TR29JN21.070

[GRAPHIC] [TIFF OMITTED] TR29JN21.071

[GRAPHIC] [TIFF OMITTED] TR29JN21.072

[GRAPHIC] [TIFF OMITTED] TR29JN21.073

[GRAPHIC] [TIFF OMITTED] TR29JN21.074

[GRAPHIC] [TIFF OMITTED] TR29JN21.075

[GRAPHIC] [TIFF OMITTED] TR29JN21.076

[GRAPHIC] [TIFF OMITTED] TR29JN21.077

[GRAPHIC] [TIFF OMITTED] TR29JN21.078

[GRAPHIC] [TIFF OMITTED] TR29JN21.079

[GRAPHIC] [TIFF OMITTED] TR29JN21.080

[GRAPHIC] [TIFF OMITTED] TR29JN21.081

[GRAPHIC] [TIFF OMITTED] TR29JN21.082

[GRAPHIC] [TIFF OMITTED] TR29JN21.083

[GRAPHIC] [TIFF OMITTED] TR29JN21.084

[GRAPHIC] [TIFF OMITTED] TR29JN21.085

    (c) The following transient duty cycle applies for compression
ignition engines and powertrains:

[GRAPHIC] [TIFF OMITTED] TR29JN21.086

[GRAPHIC] [TIFF OMITTED] TR29JN21.087

[GRAPHIC] [TIFF OMITTED] TR29JN21.088

[GRAPHIC] [TIFF OMITTED] TR29JN21.089

[GRAPHIC] [TIFF OMITTED] TR29JN21.090

[GRAPHIC] [TIFF OMITTED] TR29JN21.091

[GRAPHIC] [TIFF OMITTED] TR29JN21.092

[GRAPHIC] [TIFF OMITTED] TR29JN21.093

[GRAPHIC] [TIFF OMITTED] TR29JN21.094

[GRAPHIC] [TIFF OMITTED] TR29JN21.095

[GRAPHIC] [TIFF OMITTED] TR29JN21.096

[GRAPHIC] [TIFF OMITTED] TR29JN21.097

[GRAPHIC] [TIFF OMITTED] TR29JN21.098

[GRAPHIC] [TIFF OMITTED] TR29JN21.099

[GRAPHIC] [TIFF OMITTED] TR29JN21.100

[GRAPHIC] [TIFF OMITTED] TR29JN21.101

[GRAPHIC] [TIFF OMITTED] TR29JN21.102

[GRAPHIC] [TIFF OMITTED] TR29JN21.103

[GRAPHIC] [TIFF OMITTED] TR29JN21.104

[GRAPHIC] [TIFF OMITTED] TR29JN21.105

[GRAPHIC] [TIFF OMITTED] TR29JN21.106

[GRAPHIC] [TIFF OMITTED] TR29JN21.107

[GRAPHIC] [TIFF OMITTED] TR29JN21.108

[GRAPHIC] [TIFF OMITTED] TR29JN21.109

[GRAPHIC] [TIFF OMITTED] TR29JN21.110

[GRAPHIC] [TIFF OMITTED] TR29JN21.111

BILLING CODE 6560-50-C

PART 1037--CONTROL OF EMISSIONS FROM NEW HEAVY-DUTY MOTOR VEHICLES

0
127. The authority citation for part 1037 continues to read as follows:

    Authority:  42 U.S.C. 7401-7671q.

0
128. Amend Sec.  1037.103 by revising paragraph (c) to read as follows:

Sec.  1037.103  Evaporative and refueling emission standards.

* * * * *
    (c) Compliance demonstration. You may provide a statement in the
application for certification that vehicles above 14,000 pounds GVWR
comply with evaporative and refueling emission standards in this
section instead of submitting test data if you include an engineering
analysis describing how vehicles include design parameters, equipment,
operating controls, or other elements of design that adequately
demonstrate that vehicles comply with the standards throughout the
useful life. We would expect emission control components and systems to
exhibit a comparable degree of control relative to vehicles that comply
based on testing. For example, vehicles that comply under this
paragraph (c) should rely on comparable material specifications to
limit fuel permeation, and components should be sized and calibrated to
correspond with the appropriate fuel capacities, fuel flow rates, purge
strategies, and other vehicle operating characteristics. You may
alternatively show that design parameters are comparable to those for
vehicles at or below 14,000 pounds GVWR certified under 40 CFR part 86,
subpart S.
* * * * *

0
129. Amend Sec.  1037.105 by revising paragraph (h)(1) to read as
follows:

Sec.  1037.105  CO2 emission standards for vocational vehicles.

* * * * *
    (h) * * *
    (1) The following alternative emission standards apply by vehicle
type and model year as follows:

                          Table 5 of Sec.   1037.105--Phase 2 Custom Chassis Standards
                                                  [g/ton-mile]
----------------------------------------------------------------------------------------------------------------
                Vehicle type a                  Assigned vehicle service class     MY 2021-2026      MY 2027+
----------------------------------------------------------------------------------------------------------------
School bus...................................  Medium HDV......................              291             271
Motor home...................................  Medium HDV......................              228             226
Coach bus....................................  Heavy HDV.......................              210             205
Other bus....................................  Heavy HDV.......................              300             286
Refuse hauler................................  Heavy HDV.......................              313             298
Concrete mixer...............................  Heavy HDV.......................              319             316
Mixed-use vehicle............................  Heavy HDV.......................              319             316
Emergency vehicle............................  Heavy HDV.......................              324             319
----------------------------------------------------------------------------------------------------------------
a Vehicle types are generally defined in Sec.   1037.801. ``Other bus'' includes any bus that is not a school
  bus or a coach bus. A ``mixed-use vehicle'' is one that meets at least one of the criteria specified in Sec.
  1037.631(a)(1) and at least one of the criteria in Sec.   1037.631(a)(2), but not both.

* * * * *

0
130. Amend Sec.  1037.106 by revising paragraphs (b) and (f)(2)(i) to
read as follows:

Sec.  1037.106  Exhaust emission standards for tractors above 26,000
pounds GVWR.

* * * * *
    (b) The CO2 standards for tractors above 26,000 pounds
GVWR in Table 1 of this section apply based on modeling and testing as
described in subpart F of this part. The provisions of Sec.  1037.241
specify how to comply with the standards in this paragraph (b).

            Table 1 of Sec.   1037.106--CO2 Standards for Class 7 and Class 8 Tractors by Model Year
                                                  [g/ton-mile]
----------------------------------------------------------------------------------------------------------------
                                    Phase 1         Phase 1         Phase 2         Phase 2          Phase 2
                                 standards for   standards for   standards for   standards for    standards for
         Subcategory a            model years     model years     model years     model years    model year 2027
                                   2014-2016       2017-2020       2021-2023       2024-2026        and later
----------------------------------------------------------------------------------------------------------------
Class 7 Low-Roof (all cab                  107             104           105.5            99.8              96.2
 styles)......................
Class 7 Mid-Roof (all cab                  119             115           113.2           107.1             103.4
 styles)......................
Class 7 High-Roof (all cab                 124             120           113.5           106.6             100.0
 styles)......................
Class 8 Low-Roof Day Cab......              81              80            80.5            76.2              73.4
Class 8 Low-Roof Sleeper Cab..              68              66            72.3            68.0              64.1
Class 8 Mid-Roof Day Cab......              88              86            85.4            80.9              78.0
Class 8 Mid-Roof Sleeper Cab..              76              73            78.0            73.5              69.6
Class 8 High-Roof Day Cab.....              92              89            85.6            80.4              75.7
Class 8 High-Roof Sleeper Cab.              75              72            75.7            70.7              64.3
Heavy-Haul Tractors...........  ..............  ..............            52.4            50.2              48.3
----------------------------------------------------------------------------------------------------------------
a Subcategory terms are defined in Sec.   1037.801.

* * * * *
    (f) * * *
    (2) * * *
    (i) If you certify all your Class 7 tractors to Class 8 standards,
you may use these Heavy HDV credits without restriction. This paragraph
(f)(2)(i) applies equally for hybrid and electric vehicles.
* * * * *

0
131. Amend Sec.  1037.115 by revising paragraph (e) to read as follows:

Sec.  1037.115  Other requirements.

* * * * *
    (e) Air conditioning leakage. Loss of refrigerant from your air
conditioning systems may not exceed a total leakage rate of 11.0 grams
per year or a percent leakage rate of 1.50 percent per year,

whichever is greater. Calculate the total leakage rate in g/year as
specified in 40 CFR 86.1867-12(a). Calculate the percent leakage rate
as: [total leakage rate (g/yr)] / [total refrigerant capacity (g)] x
100. Round your percent leakage rate to the nearest one-hundredth of a
percent. This paragraph (e) applies for all refrigerants.
    (1) This paragraph (e) is intended to address air conditioning
systems for which the primary purpose is to cool the driver
compartment. This would generally include all cab-complete pickups and
vans. This paragraph (e) does not apply for refrigeration units on
trailers. Similarly, it does not apply for self-contained air
conditioning used to cool passengers or refrigeration units used to
cool cargo on vocational vehicles. Air conditioning and refrigeration
units may be considered self-contained whether or not they draw
electrical power from engines used to propel the vehicles. For purposes
of this paragraph (e), a self-contained system is an enclosed unit with
its own evaporator and condenser even if it draws power from the
engine.
    (2) For purposes of this paragraph (e), ``refrigerant capacity'' is
the total mass of refrigerant recommended by the vehicle manufacturer
as representing a full charge. Where full charge is specified as a
pressure, use good engineering judgment to convert the pressure and
system volume to a mass.
    (3) If air conditioning systems with capacity above 3,000 grams of
refrigerant are designed such that a compliance demonstration under 40
CFR 86.1867-12(a) is impossible or impractical, you may ask to use
alternative means to demonstrate that your air conditioning system
achieves an equivalent level of control.

0
132. Amend Sec.  1037.120 by revising paragraph (b)(1)(i) and (ii) to
read as follows:

Sec.  1037.120  Emission-related warranty requirements.

* * * * *
    (b) * * *
    (1) * * *
    (i) 5 years or 50,000 miles for Light HDV (except tires).
    (ii) 5 years or 100,000 miles for Medium HDV and Heavy HDV (except
tires).
* * * * *

Sec.  1037.135  [Amended]

0
133. Amend Sec.  1037.135 by removing and reserving paragraph (c)(4).

0
134. Amend Sec.  1037.140 by revising paragraphs (g) and (h) to read as
follows:

Sec.  1037.140  Classifying vehicles and determining vehicle
parameters.

* * * * *
    (g) The standards and other provisions of this part apply to
specific vehicle service classes for tractors and vocational vehicles
as follows:
    (1) Phase 1 and Phase 2 tractors are divided based on GVWR into
Class 7 tractors and Class 8 tractors. Where provisions of this part
apply to both tractors and vocational vehicles, Class 7 tractors are
considered ``Medium HDV'' and Class 8 tractors are considered ``Heavy
HDV''. This paragraph (g)(1) applies for electric, hybrid, and non-
hybrid vehicles.
    (2) Phase 1 vocational vehicles are divided based on GVWR. ``Light
HDV'' includes Class 2b through Class 5 vehicles; ``Medium HDV''
includes Class 6 and Class 7 vehicles; and ``Heavy HDV'' includes Class
8 vehicles.
    (3) Phase 2 vocational vehicles propelled by engines subject to the
spark-ignition standards of 40 CFR part 1036, ``Light HDV'' includes
Class 2b through Class 5 vehicles, and ``Medium HDV'' includes Class 6
through Class 8 vehicles.
    (4) Phase 2 vocational vehicles propelled by engines subject to the
compression-ignition standards in 40 CFR part 1036 are divided as
follows:
    (i) Class 2b through Class 5 vehicles are considered ``Light HDV''.
    (ii) Class 6 through 8 vehicles are considered ``Heavy HDV'' if the
installed engine's primary intended service class is heavy heavy-duty
(see 40 CFR 1036.140).
    (iii) Class 8 hybrid and electric vehicles are considered ``Heavy
HDV'', regardless of the engine's primary intended service class.
    (iv) All other Class 6 through Class 8 vehicles are considered
``Medium HDV''.
    (5) In certain circumstances, you may certify vehicles to standards
that apply for a different vehicle service class. For example, see
Sec. Sec.  1037.105(g) and 1037.106(f). If you optionally certify
vehicles to different standards, those vehicles are subject to all the
regulatory requirements as if the standards were mandatory.
    (h) Use good engineering judgment to identify the intended
regulatory subcategory (Urban, Multi-Purpose, or Regional) for each of
your vocational vehicle configurations based on the expected use of the
vehicles.

0
135. Amend Sec.  1037.150 by revising paragraphs (c), (q)(2), (s), (u),
(x) introductory text, (y), (z), and (aa) to read as follows:

Sec.  1037.150  Interim provisions.

* * * * *
    (c) Small manufacturers. The following provisions apply for small
manufacturers:
    (1) Small manufacturers are not subject to the greenhouse gas
standards of Sec.  1037.107 for trailers with a date of manufacture
before January 1, 2019.
    (2) The greenhouse gas standards of Sec. Sec.  1037.105 and
1037.106 are optional for small manufacturers producing vehicles with a
date of manufacture before January 1, 2022. In addition, small
manufacturers producing vehicles that run on any fuel other than
gasoline, E85, or diesel fuel may delay complying with every later
standard under this part by one model year.
    (3) Qualifying manufacturers must notify the Designated Compliance
Officer each model year before introducing excluded vehicles into U.S.
commerce. This notification must include a description of the
manufacturer's qualification as a small business under 13 CFR 121.201.
Manufacturers must label excluded vehicles with the following
statement: ``THIS VEHICLE IS EXCLUDED UNDER 40 CFR 1037.150(c).''
    (4) Small manufacturers may meet Phase 1 standards instead of Phase
2 standards in the first year Phase 2 standards apply to them if they
voluntarily comply with the Phase 1 standards for the full preceding
year. Specifically, small manufacturers may certify their model year
2022 vehicles to the Phase 1 greenhouse gas standards of Sec. Sec.
1037.105 and 1037.106 if they certify all the vehicles from their
annual U.S.-directed production volume to the Phase 1 standards
starting on or before January 1, 2021.
    (5) See paragraphs (r), (t), (y), and (aa) of this section for
additional allowances for small manufacturers.
* * * * *
    (q) * * *
    (2) For vocational vehicles and tractors subject to Phase 2
standards, create separate vehicle subfamilies if there is a credit
multiplier for advanced technology; group those vehicles together in a
vehicle subfamily if they use the same multiplier.
* * * * *
    (s) Confirmatory testing for Falt-aero. If we conduct coastdown
testing to verify your Falt-aero value for Phase 2 tractors,
we will make our determination using the principles of SEA testing in
Sec.  1037.305. We will not replace your Falt-aero value if
the tractor passes. If your tractor fails, we will generate a
replacement value of Falt-aero based on at least one
CdA value and corresponding

effective yaw angle, Ceff, from a minimum of 100 valid runs
using the procedures of Sec.  1037.528(h). Note that we intend to
minimize the differences between our test conditions and those of the
manufacturer by testing at similar times of the year where possible and
the same location where possible and when appropriate.
* * * * *
    (u) Streamlined preliminary approval for trailer devices. Before
January 1, 2018, manufacturers of aerodynamic devices for trailers may
ask for preliminary EPA approval of compliance data for their devices
based on qualifying for designation under the SmartWay program based on
measured CdA values, whether or not that involves testing or
other methods specified in Sec.  1037.526. Trailer manufacturers may
certify based on [Delta]CdA values established under this
paragraph (u) through model year 2020. Manufacturers must perform
testing as specified in subpart F of this part for any vehicles or
aerodynamic devices not qualifying for approval under this paragraph
(u).
* * * * *
    (x) Aerodynamic testing for trailers. Section 1037.526 generally
requires you to adjust [Delta]CdA values from alternate test
methods to be equivalent to measurements with the primary test method.
This paragraph (x) describes approximations that we believe are
consistent with good engineering judgment; however, you may not use
these approximations where we determine that clear and convincing
evidence shows that they would significantly overestimate actual
improvements in aerodynamic performance.
* * * * *
    (y) Transition to Phase 2 standards. The following provisions allow
for enhanced generation and use of emission credits from Phase 1
tractors and vocational vehicles for meeting the Phase 2 standards:
    (1) For vocational Light HDV and vocational Medium HDV, emission
credits you generate in model years 2018 through 2021 may be used
through model year 2027, instead of being limited to a five-year credit
life as specified in Sec.  1037.740(c). For Class 8 vocational vehicles
with medium heavy-duty engines, we will approve your request to
generate these credits in and use these credits for the Medium HDV
averaging set if you show that these vehicles would qualify as Medium
HDV under the Phase 2 program as described in Sec.  1037.140(g)(4).
    (2) You may use the off-cycle provisions of Sec.  1037.610 to apply
technologies to Phase 1 vehicles as follows:
    (i) You may apply an improvement factor of 0.988 for tractors and
vocational vehicles with automatic tire inflation systems on all axles.
    (ii) For vocational vehicles with automatic engine shutdown systems
that conform with Sec.  1037.660, you may apply an improvement factor
of 0.95.
    (iii) For vocational vehicles with stop-start systems that conform
with Sec.  1037.660, you may apply an improvement factor of 0.92.
    (iv) For vocational vehicles with neutral-idle systems conforming
with Sec.  1037.660, you may apply an improvement factor of 0.98. You
may adjust this improvement factor if we approve a partial reduction
under Sec.  1037.660(a)(2); for example, if your design reduces fuel
consumption by half as much as shifting to neutral, you may apply an
improvement factor of 0.99.
    (3) Small manufacturers may generate emission credits for natural
gas-fueled vocational vehicles as follows:
    (i) Small manufacturers may certify their vehicles instead of
relying on the exemption of paragraph (c) of this section. The
provisions of this part apply for such vehicles, except as specified in
this paragraph (y)(3).
    (ii) Use GEM version 2.0.1 to determine a CO2 emission
level for your vehicle, then multiply this value by the engine's FCL
for CO2 and divide by the engine's applicable CO2
emission standard.
    (4) Phase 1 vocational vehicle credits that small manufacturers
generate may be used through model year 2027.
    (z) Constraints for vocational regulatory subcategories. The
following provisions apply to determinations of vocational regulatory
subcategories as described in Sec.  1037.140:
    (1) Select the Regional regulatory subcategory if you certify the
engine based on testing only with the Supplemental Emission Test.
    (2) Select the Regional regulatory subcategory for coach buses and
motor homes you certify under Sec.  1037.105(b).
    (3) You may not select the Urban regulatory subcategory for any
vehicle with a manual or single-clutch automated manual transmission.
    (4) Starting in model year 2024, you must select the Regional
regulatory subcategory for any vehicle with a manual transmission.
    (5) You may select the Multi-purpose regulatory subcategory for any
vocational vehicle, except as specified in paragraphs (z)(1) through
(3) of this section.
    (6) You may not select the Urban regulatory subcategory for any
vehicle with a manual or single-clutch automated manual transmission.
    (7) You may select the Urban regulatory subcategory for a hybrid
vehicle equipped with regenerative braking, unless it is equipped with
a manual transmission.
    (8) You may select the Urban regulatory subcategory for any vehicle
with a hydrokinetic torque converter paired with an automatic
transmission, or a continuously variable automatic transmission, or a
dual-clutch transmission with no more than two consecutive forward
gears between which it is normal for both clutches to be momentarily
disengaged.
    (aa) Custom-chassis standards. The following provisions apply
uniquely to small manufacturers under the custom-chassis standards of
Sec.  1037.105(h):
    (1) You may use emission credits generated under Sec.  1037.105(d),
including banked or traded credits from any averaging set. Such credits
remain subject to other limitations that apply under subpart H of this
part.
    (2) You may produce up to 200 drayage tractors in a given model
year to the standards described in Sec.  1037.105(h) for ``other
buses''. The limit in this paragraph (aa)(2) applies with respect to
vehicles produced by you and your affiliated companies. Treat these
drayage tractors as being in their own averaging set.

0
136. Amend Sec.  1037.201 by revising paragraph (h) to read as follows:

Sec.  1037.201  General requirements for obtaining a certificate of
conformity.

* * * * *
    (h) The certification and testing provisions of 40 CFR part 86,
subpart S, apply instead of the provisions of this subpart relative to
the evaporative and refueling emission standards specified in Sec.
1037.103, except that Sec.  1037.243 describes how to demonstrate
compliance with evaporative emission standards. For vehicles that do
not use an evaporative canister for controlling diurnal emissions, you
may certify with respect to exhaust emissions and use the provisions of
Sec.  1037.622 to let a different company certify with respect to
evaporative emissions.
* * * * *

0
137. Amend Sec.  1037.205 by revising paragraphs (e) and (f) to read as
follows:

Sec.  1037.205  What must I include in my application?

* * * * *
    (e) Describe any test equipment and procedures that you used,
including any special or alternate test procedures you used (see Sec.
1037.501). Include information describing the procedures

you used to determine CdA values as specified in Sec. Sec.
1037.525 through 1037.527. Describe which type of data you are using
for engine fuel maps (see 40 CFR 1036.503). If your trailer
certification relies on approved data from device manufacturers,
identify the device and device manufacturer.
    (f) Describe how you operated any emission-data vehicle before
testing, including the duty cycle and the number of vehicle operating
miles used to stabilize emission-related performance. Explain why you
selected the method of service accumulation. Describe any scheduled
maintenance you did, and any practices or specifications that should
apply for our testing.
* * * * *

0
138. Amend Sec.  1037.225 by revising paragraph (e) to read as follows:

Sec.  1037.225  Amending applications for certification.

* * * * *
    (e) The amended application applies starting with the date you
submit the amended application, as follows:
    (1) For vehicle families already covered by a certificate of
conformity, you may start producing a new or modified vehicle
configuration any time after you send us your amended application and
before we make a decision under paragraph (d) of this section. However,
if we determine that the affected vehicles do not meet applicable
requirements in this part, we will notify you to cease production of
the vehicles and may require you to recall the vehicles at no expense
to the owner. Choosing to produce vehicles under this paragraph (e) is
deemed to be consent to recall all vehicles that we determine do not
meet applicable emission standards or other requirements in this part
and to remedy the nonconformity at no expense to the owner. If you do
not provide information required under paragraph (c) of this section
within 30 days after we request it, you must stop producing the new or
modified vehicles.
    (2) [Reserved]
* * * * *

0
139. Amend Sec.  1037.230 by revising paragraph (a)(2) to read as
follows:

Sec.  1037.230  Vehicle families, sub-families, and configurations.

    (a) * * *
    (2) Apply subcategories for tractors (other than vocational
tractors) as shown in Table 2 of this section.
    (i) For vehicles certified to the optional tractor standards in
Sec.  1037.670, assign the subcategories as described in Sec.
1037.670.
    (ii) For vehicles intended for export to Canada, you may assign the
subcategories as specified in the Canadian regulations.
    (iii) Table 2 follows:

            Table 2 of Sec.   1037.230--Tractor Subcategories
------------------------------------------------------------------------

------------------------------------------------------------------------
Class 7                                           Class 8
------------------------------------------------------------------------
Low-roof tractors...............  Low-roof day cabs.  Low-roof sleeper
                                                       cabs.
Mid-roof tractors...............  Mid-roof day cabs.  Mid-roof sleeper
                                                       cabs.
High-roof tractors..............  High-roof day cabs  High-roof sleeper
                                                       cabs.
                                 ---------------------------------------
                                    Heavy-haul tractors (starting with
                                                 Phase 2).
------------------------------------------------------------------------

* * * * *

0
140. Amend Sec.  1037.231 by revising paragraph (b)(7) to read as
follows:

Sec.  1037.231  Powertrain families.

* * * * *
    (b) * * *
    (7) Number of available forward gears, and transmission gear ratio
for each available forward gear, if applicable. Count forward gears as
being available only if the vehicle has the hardware and software to
allow operation in those gears.
* * * * *

0
141. Amend Sec.  1037.235 by revising paragraphs (a), (c)(2), and (h)
to read as follows:

Sec.  1037.235  Testing requirements for certification.

* * * * *
    (a) Select emission-data vehicles that represent production
vehicles and components for the vehicle family consistent with the
specifications in Sec. Sec.  1037.205(o), 1037.515, and 1037.520. Where
the test results will represent multiple vehicles or components with
different emission performance, use good engineering judgment to select
worst-case emission data vehicles or components. In the case of
powertrain testing under Sec.  1037.550, select a test engine, test
hybrid components, test axle, and test transmission as applicable, by
considering the whole range of vehicle models covered by the powertrain
family and the mix of duty cycles specified in Sec.  1037.510. If the
powertrain has more than one transmission calibration, for example
economy vs. performance, you may weight the results from the powertrain
testing in Sec.  1037.550 by the percentage of vehicles in the family
by prior model year for each configuration. This can be done, for
example, through the use of survey data or based on the previous model
year's sales volume. Weight the results of Mfuel[cycle],
[GRAPHIC] [TIFF OMITTED] TR29JN21.112

and W[cycle] from Table 2 of Sec.  1037.550 according to the
percentage of vehicles in the family that use each transmission
calibration.
* * * * *
    (c) * * *
    (2) If we measure emissions (or other parameters, as applicable)
from your vehicle or component, the results of that testing become the
official emission results for the vehicle or component. Note that
changing the official emission result does not necessarily require a
change in the declared modeling input value. These results will only
affect your vehicle FEL if the results of our confirmatory testing
result in a GEM vehicle emission value that is higher than the vehicle
FEL declared by the manufacturer. Unless we later invalidate these
data, we may decide not to consider your data in determining if your
vehicle family meets applicable requirements in this part.
* * * * *
    (h) You may ask us to use analytically derived GEM inputs for
untested configurations (such as untested axle ratios within an axle
family) as identified in subpart F of this part based on interpolation
of all relevant measured values for related configurations, consistent
with good engineering judgment. We may establish specific approval
criteria based on prevailing industry practice. If we allow this, we
may test any configuration. We

may also require you to test any configuration as part of a selective
enforcement audit.

0
142. Amend Sec.  1037.243 by revising paragraph (c) to read as follows:

Sec.  1037.243  Demonstrating compliance with evaporative emission
standards.

* * * * *
    (c) Apply deterioration factors to measured emission levels for
comparing to the emission standard in subpart B of this part. Establish
an additive deterioration factor based on an engineering analysis that
takes into account the expected aging from in-use vehicles.
* * * * *

0
143. Revise Sec.  1037.255 to read as follows:

Sec.  1037.255  What decisions may EPA make regarding my certificate of
conformity?

    (a) If we determine an application is complete and shows that the
vehicle family meets all the requirements of this part and the Act, we
will issue a certificate of conformity for the vehicle family for that
model year. We may make the approval subject to additional conditions.
    (b) We may deny an application for certification if we determine
that a vehicle family fails to comply with emission standards or other
requirements of this part or the Clean Air Act. We will base our
decision on all available information. If we deny an application, we
will explain why in writing.
    (c) In addition, we may deny an application or suspend or revoke a
certificate of conformity if you do any of the following:
    (1) Refuse to comply with any testing or reporting requirements in
this part.
    (2) Submit false or incomplete information. This includes doing
anything after submitting an application that causes submitted
information to be false or incomplete.
    (3) Cause any test data to become inaccurate.
    (4) Deny us from completing authorized activities (see 40 CFR
1068.20). This includes a failure to provide reasonable assistance.
    (5) Produce vehicles for importation into the United States at a
location where local law prohibits us from carrying out authorized
activities.
    (6) Fail to supply requested information or amend an application to
include all vehicles being produced.
    (7) Take any action that otherwise circumvents the intent of the
Act or this part.
    (d) We may void a certificate of conformity if you fail to keep
records, send reports, or give us information as required under this
part or the Act. Note that these are also violations of 40 CFR
1068.101(a)(2).
    (e) We may void a certificate of conformity if we find that you
intentionally submitted false or incomplete information. This includes
doing anything after submitting an application that causes submitted
information to be false or incomplete after submission.
    (f) If we deny an application or suspend, revoke, or void a
certificate, you may ask for a hearing (see Sec.  1037.820).

0
144. Amend Sec.  1037.301 by revising paragraph (b) to read as follows:

Sec.  1037.301  Overview of measurements related to GEM inputs in a
selective enforcement audit.

* * * * *
    (b) A selective enforcement audit for this part consists of
performing measurements with production vehicles relative to one or
more declared values for GEM inputs, and using those measured values in
place of your declared values to run GEM. Except as specified in this
subpart, the vehicle is considered passing if the new modeled emission
result is at or below the modeled emission result corresponding to the
declared GEM inputs. If you report an FEL for the vehicle configuration
before the audit, we will instead consider the vehicle passing if the
new cycle-weighted emission result is at or below the FEL.
* * * * *

0
145. Amend Sec.  1037.305 by revising the introductory text and
paragraph (a) to read as follows:

Sec.  1037.305  Audit procedures for tractors--aerodynamic testing.

    To perform a selective enforcement audit with respect to drag area
for tractors, use the reference method specified in Sec.  1037.525; we
may instead require you to use the same method you used for
certification. The following provisions apply instead of 40 CFR
1068.415 through 1068.425 for a selective enforcement audit with