56
                                      18

Hood Support Structure System
                                      15
                                       3

Hood and Front Fender

                                      65
Day Cab Roof Fairing

                                      18
Sleeper Cab Roof Fairing
                                      75
                                      20
                                      40
Aerodynamic Side Extender

                                      10
Fairing Support Structure System
                                      35
                                       6

Instrument Panel Support Structure
                                       5
                                       1

Brake Drums  -  Drive (4)
                                      140
                                      11

Brake Drums  -  Non Drive (2)
                                      60
                                       8

Frame Rails
                                      440
                                      87

Crossmember  -  Cab
                                      15
                                       5

Crossmember  -  Suspension
                                      25
                                       6

Crossmember  -  Non Suspension (3)
                                      15
                                       5

Fifth Wheel
                                      100
                                      25

Radiator Support
                                      20
                                       6

Fuel Tank Support Structure
                                      40
                                      12

Steps
                                      35
                                       6

Bumper
                                      33
                                      10

Shackles
                                      10
                                       3

Front Axle
                                      60
                                      15

Suspension Brackets, Hangers
                                      100
                                      30

Transmission Case
                                      50
                                      12

Clutch Housing
                                      40
                                      10

Fairing Support Structure System
                                      35
                                       6

Drive Axle Hubs (per 4)
                                      80
                                      20

Non Drive Front Hubs (2)
                                      40
                                       5

Driveshaft
                                      20
                                       5

Transmission/Clutch Shift Levers
                                      20
                                       4

Table 10 to §1037.520 -- Unit Weight Reductions for Phase 2 Vocational Vehicles (pounds)
COMPONENT
MATERIAL
VEHICLE TYPE

Class 2b-7 Vocational Vehicle
Class 8 Vocational Vehicle
Axle Hubs  -  Drive
Aluminum
                                      20
                                      20
Axle Hubs  -  Drive
High Strength Steel
                                       5
                                       5
Axle Hubs - Non-Drive
Aluminum
                                      20
                                      20
Axle Hubs - Non-Drive
High Strength Steel
                                      2.5
                                      2.5
Axle  -  Non-Drive
Aluminum
                                      60
                                      60
Axle  -  Non-Drive
High Strength Steel
                                      15
                                      15
Axle - 6x2 Configuration
Multi
                                      N/A
                                      300
Brake Drums  -  Drive
Aluminum
                                      35
                                      35
Brake Drums  -  Drive
High Strength Steel
                                      2.8
                                      2.8
Brake Drums - Non-Drive
Aluminum
                                      30
                                      30
Brake Drums - Non-Drive
High Strength Steel
                                       4
                                       4
Crossmember  -  Cab
Aluminum
                                      15
                                      15
Crossmember  -  Cab
High Strength Steel
                                       5
                                       5
Crossmember - Non-Suspension
Aluminum
                                       5
                                       5
Crossmember - Non-Suspension
High Strength Steel
                                      1.7
                                      1.7
Crossmember - Suspension
Aluminu'm
                                      25
                                      25
Crossmember - Suspension
High Strength Steel
                                       6
                                       6
Driveshaft
Aluminum
                                      20
                                      20
Driveshaft
High Strength Steel
                                       5
                                       5
Frame Rails
Aluminum
                                      220
                                      220
Frame Rails
High Strength Steel
                                      43
                                      43
Shackles
Aluminum
                                      10
                                      10
Shackles
High Strength Steel
                                       3
                                       3
Suspension Brackets, Hangers
Aluminum
                                      100
                                      100
Suspension Brackets, Hangers
High Strength Steel
                                      30
                                      30
Transmission Case
Aluminum
                                      45
                                      50
Transmission Case
High Strength Steel
                                      12
                                      12
Clutch Housing
Aluminum
                                      34
                                      47
Clutch Housing
High Strength Steel
                                      10
                                      10
Clutch Levers
Aluminum
                                      20
                                      20
Clutch Levers
High Strength Steel
                                       4
                                       4

Table 11 to §1037.520 -- Weight Reductions for Trailers (pounds)
COMPONENT
MATERIAL
WEIGHT REDUCTION (POUNDS)
Structure for Suspension Assembly[1]
 Aluminum
                                      280
Hub and Drum (per axle)
Aluminum
                                      80
Floor
Aluminum
                                      375
Floor
Composite (wood and plastic)
                                      245
Floor Crossmembers
 Aluminum
                                      203
Landing Gear
 Aluminum
                                      50
Rear Door
 Aluminum
                                      187
Rear Door Surround
 Aluminum
                                      150
Roof Bows
 Aluminum
                                      100
Side Posts
 Aluminum
                                      300
Slider Box
 Aluminum
                                      150
Upper Coupler Assembly
 Aluminum
                                      430
[1] For tandem-axle suspension sub-frames made of aluminum, apply a weight reduction of 280 pounds.  Use good engineering judgment to estimate a weight reduction for using aluminum sub-frames with other axle configurations.

   (3) Apply vehicle weight inputs for changing technology configurations as follows:
      (i) For Class 8 tractors or Class 8 vocational vehicles with permanent 6x2 axle configuration, apply a weight reduction input of 300 pounds.
      (ii) For Class 8 tractors with 4x2 axle configuration, apply a weight reduction input of 400 pounds.
      (iii) For tractors with installed engines with displacement below 14.0 liters, apply a weight reduction of 300 pounds.
      (iv) For vehicles that use a fuel other than diesel fuel, gasoline, or natural gas, use good engineering judgment to determine an appropriate weight adjustment relative to a comparable vehicle fueled by gasoline or diesel fuel.
   (4) You may ask to apply the off-cycle technology provisions of §1037.610 for weight reductions not covered by this paragraph (e).
(f) Additional vehicle characteristics.  GEM accounts for CO2 emission reductions for certain technologies and vehicle configurations as noted in this paragraph (f) for Phase 2 vehicles.  Because these adjustments are made internal to GEM, you need to identify the features as GEM inputs rather than separately applying these adjustments to GEM results.  These adjustments are summarized for informational purposes only.
   (1) GEM applies a 2.5 % emission reduction for single drive axles with the following Class 8 vehicles:
      (i) Tractors in a 4x2 configuration.
      (ii) Tractors and vocational vehicles with a permanent 6x2 configuration.  The same emission reduction applies for part-time 6x2 configurations, but only for the cruise cycles specified in §1037.510.
   (2) GEM applies a 0.5 % emission reduction for vehicles that use a low-friction drive axle lubricant, as follows:
      (i) A lubricant qualifies if it meets the specifications for BASF Emgard FE 2986 as described in "Emgard[(R)] FE 75W-90 Fuel Efficient Synthetic Gear Lubricant" (incorporated by reference in § 1037.810).
      (ii) You may use A to B testing using the procedures in §1037.515 to show that a lubricant performs at an equivalent or superior level relative to a lubricant specified in paragraph (f)(2)(i) of this section.  Testing must show equivalent or superior performance at every specified speed and torque value.
   (3) GEM applies a 2 % emission reduction for tractors if they have an automatic transmission, an automated manual transmission, or a dual-clutch transmission.  Similarly, GEM applies a 2.3 % emission reduction for Class 8 vocational vehicles certified with the Regional duty cycle if they have an automated manual transmission or a dual-clutch transmission.
   (4) GEM applies a 2 % emission reduction for tractors with predictive cruise control.  This includes any cruise control system that incorporates satellite-based global-positioning data for controlling operator demand.
   (5) GEM applies a 0.5 % emission reduction for tractors with a high-efficiency air conditioning compressor.  This includes mechanically powered compressors meeting the specifications described in 40 CFR 86.1868-12(h)(5), and all electrically powered compressors.
   (6) GEM applies a 1 % emission reduction for tractors with electrically powered pumps for steering and engine cooling.
   (7) GEM applies a 1 % emission reduction for tractors with automatic tire inflation systems.  The corresponding emission reduction for trailers is 1.5 %.
   (8) GEM accounts for emission reductions for reduced idle for the following technologies:
      (i) Stop-start technology for vocational vehicles. Phase 2 vocational vehicles qualify for reduced emissions in GEM modeling if the engine shuts down no more than 30 seconds after the onset of any of the following conditions:
         (A) The vehicle's brake is depressed at a zero-speed condition.
         (B) A vehicle with automatic transmission goes into "Park".
      (ii) Neutral-idle technology for vocational vehicles. A Phase 2 vocational vehicle with an automatic transmission qualifies for reduced emissions in GEM modeling if the vehicle goes into neutral (or reduces torque equivalent to being in neutral) at a zero-speed condition.
      (iii)  Extended-idle reduction.  If your tractor is equipped with idle reduction technology meeting the requirements of §1037.660 that will automatically shut off the main engine after 300 seconds or less, GEM applies a 5 percent emission reduction for Phase 2 vehicles.  For Phase 1, enter 5.0 g/ton-mile as the input (or a lesser value specified in §1037.660); otherwise leave this field blank.
(g) Engine fuel mapping.  Use the fuel map from the engine manufacturer to characterize the engine's specific fuel consumption, or create a new fuel map as described in 40 CFR 1036.535.
(h) Engine full-load torque curve and motoring torque curve.  Use the full-load torque curve and the motoring torque map from the engine manufacturer or create new maps as described in 40 CFR 1065.510(b) and (c).
(i) [Reserved]
(j) Vehicles with hybrid power takeoff.  Determine the delta PTO emission result of your engine and hybrid power takeoff system as described in § 1037.540.
(k) Alternate fuels.  For fuels other than those identified in 40 CFR 1036.530(b), use GEM to simulate your vehicle as a diesel-fueled vehicle, but use a fuel map based on the mass flow rates of the alternate fuel.

§ 1037.525  Aerodynamic measurements.
This section describes a methodology for determining aerodynamic drag area, CDA for use in determining GEM inputs as described in §1037.520.
(a) General provisions for trailers.  The GEM input for a trailer's aerodynamic performance is based on a delta CDA value relative to a baseline trailer.  Determine these delta CDA values by performing A to B testing using one of the procedures specified in §§1037.527 through 1037.533.  Determine a baseline CDA value for a standard tractor pulling a test trailer representing a production configuration.  Repeat this testing with the same tractor, or a nominally equivalent tractor, and a baseline trailer.  For testing long trailers, the baseline trailer is a trailer meeting the specifications for a Phase 1 standard trailer in §1037.501(g)(1).  For testing short trailers, use a baseline trailer that meets the same specifications, except that you may make any appropriate adjustments to the specified dimensions to represent a production configuration; also, in the case of trailers less than 35 feet long, use a baseline trailer with a single axle.  Use good engineering judgment to perform paired tests that accurately demonstrate the reduction in aerodynamic drag associated with the improved design.  Calculate a delta CDA by subtracting the drag area for the test trailer from the drag area for the baseline trailer.  Submit information describing how you determined CDA values as described in §§1037.527 through 1037.533, as applicable.
(b) General provisions for tractors.  The GEM input for a tractor's aerodynamic performance is an absolute CDA value that is measured or calculated for a tractor in a test configuration.  Test high-roof tractors with a standard box trailer.  Test low-roof and mid-roof tractors without a trailer; however, you may test low-roof and mid-roof tractors with a trailer to evaluate off-cycle technologies.  The default method for determining CDA values is a coastdown procedure as specified in §1037.527.  You may instead use one of the alternative methods specified in §§1037.529 through 1037.533, or some other method, based on a correlation to coastdown testing, consistent with good engineering judgment.  Submit information describing how you determined CDA values from coastdown testing whether or not you use an alternative method.  If you determine drag area using an alternative method, CDAalt, you must submit additional information as described in §§1037.527 through 1037.533, as applicable, and adjust the CDA values to be equivalent to the corresponding values from coastdown measurements as follows:
   (1) Unless good engineering judgment requires otherwise, assume that coastdown drag areas are proportional to drag areas measured using alternative methods.  This means you may apply a single constant adjustment factor, Falt-aero, for a given alternate drag area method using the following equation:
      CDA = CDAalt ∙ Falt-aero
   (2) Determine Falt-aero by performing coastdown testing and applying your alternate method on the same vehicle.  Unless we approve another vehicle, the vehicle must be a Class 8, high-roof, sleeper cab with a full aerodynamics package, pulling a standard trailer.  Where you have more than one tractor model meeting these criteria, use the tractor model with the highest projected sales.  If you do not have such a tractor model, you may use your most comparable tractor model with our prior approval.
   (3) For Phase 2 testing, use good engineering judgment to calculate a unique Falt-aero for each a high-roof day cab and a high-roof sleeper cab corresponding to each major tractor model.  You must also determine unique values of Falt-aero for low-roof and mid-roof tractors if you determine CDA values based on equivalent high-roof tractor testing as shown in Table 5 of § 1037.520.  For Phase 1 testing, if good engineering judgment allows it, you may calculate a single, constant value of Falt-aero for your whole product line by dividing the coastdown drag area, CDAcoast, by CDAalt.
   (4) Calculate Falt-aero to at least three decimal places.  For example, if your coastdown testing results in a drag area of 6.430, but your wind tunnel method results in a drag area of 6.200, Falt-aero would be 1.037.
(c) Approval of alternative methods for tractors.  You must obtain preliminary approval before using any method other than coastdown testing to determine drag coefficients for tractors.  Send your request for approval to the Designated Compliance Officer.  Keep records of the information specified in this paragraph (c).  Unless we specify otherwise, include this information with your request.  You must provide any information we require to evaluate whether you may apply the provisions of this section, consistent with good engineering judgment.  Include additional information related to your alternative method as described in §§1037.529 through 1037.533.  If you use a different alternative method, include all the following information, as applicable:
      (1) Official name/title of the procedure.
      (2) Description of the procedure.
      (3) Cited sources for any standardized procedures that the method is based on.
      (4) Description and rationale for any modifications/deviations from the standardized procedures.
      (5) Data comparing the procedure to the coastdown reference procedure.
      (6) Additional information specified for the alternative methods described in §§1037.529 through 1037.533 as applicable to this method (e.g., source location/address, background/history).
(d) Yaw sweep corrections.  Vehicle aerodynamic features can be more effective at reducing wind-averaged drag than is predicted by zero-yaw drag.
   (1) For Phase 2 testing, apply the following method based on SAE J1252 (incorporated by reference in §1037.810):
      (i) Determine the zero-yaw drag area, CDAzero, and the yaw-sweep drag area for your vehicle using the same alternate method.  For the yaw sweep drag area, measure the drag area, at a minimum, at yaw angles of 0°, +-1°, +-3°, +-6°, and +-9°, where 0° represents the direction of travel.  Alternatively, using good engineering judgment with demonstration of equivalency and our prior approval, you may measure the drag area using different or fewer yaw angles than those specified above, provided they satisfy the requirements for SAE J1252, unless otherwise demonstrated.
      (ii)  Calculate the wind-averaged coefficient of drag according to SAE J1252.
(iii) For the tractor used to determine Falt-aero, determine your wind-averaged drag area, CDAwa, using the following equation:
         CDAwa = CDAzero,coastdown + (CDAwa,alt method  -  CDAzero,alt method) ∙ Falt-aero
         		Eq. 1037.525-1
(iv) For additional tractors using an alternative method and predetermined Falt-aero, use the following equation to determine CDAwa:
         CDAwa = CDAwa,alt method ∙ Falt-aero
         		Eq. 1037.525-2
(v) Instead of testing, you may use a default adjustment of 0.80 m[2] using the following equation:
         CDAwa = CDAzero + 0.80
         		Eq. 1037.525-3
    (2) For Phase 1 testing, you may correct your zero-yaw drag area as follows if the ratio of the zero-yaw drag area divided by yaw-sweep drag area for your vehicle is greater than 0.8065 for  +-6° yaw angle or 0.8350 for wind-averaged drag  (which represents the ratios expected for a typical Class 8 high-roof sleeper cab):
      (i) Determine the zero-yaw drag area and the yaw-sweep drag area for your vehicle using the same alternate method as specified in this subpart.  Measure the drag area for 0°,  - 6°, and +6°.  Use the arithmetic mean of the  - 6° and +6° drag areas as the +-6° drag area.
      (ii)  Calculate your yaw-sweep correction factor, CFys, using the following equation:

		Eq. 1037.525-4
      (iii) You may instead calculate the wind-averaged drag area according to SAE J1252 (incorporated by reference in §1037.810) and substitute this value into Equation 1037.525-4 for the +-6° yaw-averaged drag area.  If you choose to calculate the wind-averaged drag area according to SAE J1252, calculate your yaw-sweep correction factor, CFys, using the following equation:

   		Eq. 1037.525-5
      (iv) Calculate your corrected drag area for determining the aerodynamic bin by multiplying the measured zero-yaw drag area by CFys as determined using Equation 1037.525-4 or 1037.525-5, as applicable.  The correction factor may be applied to drag areas measured using other procedures.  For example, we would apply CFys to drag areas measured using the recommended coastdown method.  If you use an alternative method, you would also need to apply an alternative correction, Falt-aero, and calculate the final drag area using the following equation:
      	CDA = Falt-aero ∙ CFys ∙ CDAzero-alt
		Eq. 1037.525-6
      (v) You may ask us to apply CFys to similar vehicles incorporating the same design features.

§ 1037.527 Coastdown procedures for calculating drag area (CDA).
The coastdown procedures in this section describe how to calculate drag area, CDA, with Phase 2 tractors and trailers.  Follow the provisions of Sections 1 through 9 of SAE J1263 and SAE J2263 (incorporated by reference in § 1037.810), with the following clarifications and exceptions:
(a) The terms and variables identified in this section have the meaning given in SAE J1263 and J2263 unless specified otherwise.
(b) Prepare tractors and trailers for testing by installing tires mounted on steel rims in a dual configuration (except for steer tires).  The tires must -
   (1) Be SmartWay-Verified or have a rolling resistance below 5.1 kg/ton.
   (2) Have accumulated at least 2,175 miles but have no less than 50 percent of their original tread depth, as specified for truck cabs in SAE J1263 (incorporated by reference in §1037.810).
   (3) Not be retreads or have any apparent signs of chunking or uneven wear.(4) Be size 295/75R22.5 or 275/80R22.5.
(c) The test condition specifications of SAE J1263 apply, with the following exceptions:
   (1) We recommend that you not perform coastdown testing if winds are expected to exceed 6.0 mph.
   (2) Road conditions should follow Section 7.4 of SAE J1263, except that road grade may exceed 0.5 %; however, the road grade for testing must not be excessive, considering factors such as coastdown effects and road safety standards.
   (3) If road grade is greater than 0.02% over the length of the test surface, you must determine road grade as a function of distance along the length of the test surface and incorporate this into the analysis.  Use Section 11.5 of SAE J2263 to calculate the force due to grade.
(d) Measure vehicle speed at 10 Hz, in conjunction with time-of-day data.  Select one of the following options to determine vehicle speed:
   (1) Operate the vehicle at a top speed above 70 mph; start the test at or above 70 mph.  Collect data through a minimum speed at or below 15 mph.  Disable any vehicle speed limiters that prevent travel above 70 mph.  If a vehicle cannot exceed 70 mph, start the test at the vehicle's maximum achievable speed.  Data analysis for valid coastdown runs must include the range of vehicle speeds specified in this paragraph (d)(1).  Perform a minimum of sixteen valid coastdown runs (eight in each direction).
   (2) Perform a high-speed coastdown from 70 to 60 mph and a separate low-speed coastdown from 25 to 15 mph.  For each speed range, start the test at least 2 mph above the specified maximum speed and collect data through at least 2 mph below the specified minimum speed.  Perform two to four high-speed coastdowns consecutively in one direction followed by the same number of low-speed coastdowns in the same direction, then perform that same number of measurements in the opposite direction.  Repeat this process until you have performed twelve valid high-speed coastdowns and twelve valid low-speed coastdowns in each direction.
(e) Measure wind speed, wind direction, air temperature, and air pressure at 1 Hz, in conjunction with time-of-day data.  Use at least one stationary electro-mechanical anemometer and suitable data loggers meeting SAE J1263 specifications, subject to the following additional specifications for the anemometer placed along the test surface:
   (1) You must start a coastdown measurement within 24 hours after running zero-wind and zero-angle calibrations.
   (2) Place the anemometer at least 50 feet from the nearest tree and at least 25 feet from the nearest bush (or equivalent features).  Position the anemometer adjacent to the test surface, near the midpoint of the length of the track, between 2.5 and 3.0 body widths from the expected location of the test vehicle's centerline as it passes the anemometer.  Record the location of the anemometer relative to a reference point along the test track, to the nearest 10 feet.
   (3) Mount the anemometer at a height that is within 6 inches of half the test vehicle's body height.
   (4) The height of vegetation surrounding the anemometer may not exceed 10 % of the anemometer's mounted height, within a radius equal to the anemometer's mounted height.
(f) Measure air speed and air direction onboard the vehicle at 10 Hz, in conjunction with time-of-day data, using an anemometer and suitable data loggers that meet the requirements of Sections 5.4 and 5.5 of SAE J2263.  Mount the anemometer 1 meter above the top of the leading edge of the trailer. Correct anemometer measurements using the wind speed and wind direction measurements described in paragraph (e) of this section as follows:
   (1) Calculate arithmetic mean values for vehicle speed, air speed, wind speed, wind direction over each 5-mph vehicle speed increment for each coastdown.
   (2) Calculate the theoretical air speed, vair,th, for each 5-mph increment using the following equation:

               Eq. 1037.523-1
      Where:
      = the mean wind speed over each 5-mph increment.
      = the mean vehicle speed over each 5-mph increment.
      = the mean wind direction over each 5-mph increment.  Let = 0 for air flow in travel direction 1, with values increasing counterclockwise.  For example, if the vehicle is traveling eastbound in direction 1, then = 270° means a wind from the south.
   (3) Perform a linear regression using all paired values of  and measured air speed, , to determine the air-speed correction coefficients, α0 and α1, based on the following equation:

               Eq. 1037.523-2
   (4) Correct measured air speed using the following equation:

               Eq. 1037.523-3
(g) You may split runs as described in paragraph (d)(2) of this section, but you may not split runs as described in Section 9.3.1 of SAE J2263.
(h) Follow the procedures specified in Section 10 of SAE J1263 or Section 11 of SAE J2263 to calculate coefficients for the road-load force equation.  Determine drag area, CDA, using the following procedure instead of what is specified in Section 10 of SAE J1263:
   (1) Calculate the vehicle's effective mass, Me, to account for rotational inertia by adding 56.7 kg to the measured vehicle mass, M, (in kg) for each tire making road contact.
   (2) Calculate mean vehicle speed at each speed endpoint (70, 60, 25, and 15 mph) as follows:
      (i) Determine the timestamp corresponding to the point at which vehicle speed falls to 2.00 mph above the nominal starting speed of each speed range (70 or 25 mph), and determine the timestamp corresponding to vehicle speed 2.00 mph below the same speed setpoint. Consider the midpoint of this time range to be the time at which the vehicle reaches the starting speed.
      (ii) Repeat the calculation described in paragraph (h)(2)(i) of this section corresponding to the endpoint speed (60 or 15 mph) to determine the time at which the vehicle reaches the ending speed.
      (iii) Calculate the vehicle's average speed between the time that the vehicle reaches the starting and ending speeds for each interval by averaging the vehicle speed measurements in each interval, expressed in m/s to at least two decimal places.
		(iv) If you correct for grade, also determine the change in elevation and the distance traveled during the interval, by averaging the elevation and distance traveled over each interval.
   (3) Calculate the road-load force, F, for each speed range using the following equation:

               Eq. 1037.523-4

   Where:
   Me = the vehicle's effective mass, in kg, expressed to at least the nearest 0.1 kg.
    = average vehicle speed at the start or end of each speed range.
   = timestamp at which the vehicle reaches the starting or ending speed, in seconds, expressed to at least one decimal place.
   = average elevation at the start or end of each speed range, in m, expressed to at least one decimal place. .
    = distance traveled on the road surface  from a fixed reference location along the road to the start or end of each speed range, in m, expressed to at least one decimal place.
   Faxle = an estimate of rear-axle losses. Use 200 N for the high-speed range and 100 N for the low-speed range.
   g = gravitational acceleration = 9.81 m/s[2].
   (4) If you perform high-speed and low-speed coastdowns as described in paragraph (d)(2) of this section, average the F values for each set of consecutive low-speed runs.  Use this value as Flo in the calculations in this paragraph (h) to apply to each of the high-speed runs in a set of consecutive high-speed runs that immediately precede a set of consecutive low-speed runs. Otherwise, determine the Flo and Fhi values in the calculations in this paragraph (h) from the same run.
   (5) Calculate average air temperature  and air pressure  during each high-speed run.
   (6) Calculate average air speed during each speed range for each run, and .
   (7) Perform an iterative calculation to determine aerodynamic and mechanical forces as follows:
      (i) Assume initially that aerodynamic forces for the low-speed range are zero: Faero,lo = 0.
      (ii) Estimate high-speed aerodynamic forces by subtracting mechanical forces from the road-load force corresponding to the high-speed coastdown, Fhi, as follows:
      Faero,hi = Fhi  -  (Flo  -  Faero,lo)
      			Eq. 1037.523-5
      (iii) Calculate a new value for Faero,lo by adjusting the high-speed aerodynamic forces to account for speed, as follows:

      			Eq. 1037.523-6
      (iv) Repeat the steps in paragraphs (g)(7)(ii) and (iii) of this section until Faero,hi changes less than 1.0 %.
   (8) Calculate drag area, CDA, in m[2] for each high-speed run or segment using the following equation:

      			Eq. 1037.523-7
      Where:
       = mean air density in kg/m[3].

      			Eq. 1037.523-8
       = mean air pressure in kPa, expressed to at least one decimal place.
      R = molar gas constant = 287.058 J/(kg·K).
       = mean air temperature in °C, expressed to at least one decimal place.
  (9) Calculate an arithmetic mean CDA value from all the high-speed segments to determine the drag area for the test.
(i) [Reserved]
(j)  Include the following information in your application for certification:
   (1) The name, location, and description of your test facilities, including background/history, equipment and capability, and track and facility elevation, along with the grade and size/length of the track.
   (2) Test conditions for each test result, including date and time, wind speed and direction, ambient temperature and humidity, vehicle speed, driving distance, manufacturer name, test vehicle/model type, model year, applicable family, tire type and rolling resistance, weight of tractor-trailer (as tested), and driver identifier(s).
   (3) Average CDA result and all the individual run results (including voided or invalid runs).

   § 1037.529  Wind-tunnel procedures for calculating drag area (CDA).
    (a) You may measure drag areas consistent with the modified SAE procedures described in this section using any wind tunnel recognized by the Subsonic Aerodynamic Testing Association.  If your wind tunnel is not capable of testing in accordance with these modified SAE procedures, you may ask us to approve your alternate test procedures if you demonstrate that your procedures produce equivalent data.  For purposes of this section, data are equivalent if they are the same or better with respect to repeatability and unbiased correlation with coastdown testing.  Note that, for wind tunnels not capable of these modified SAE procedures, good engineering judgment may require you to base your alternate method adjustment factor on more than one vehicle.  You may not develop your correction factor until we have approved your alternate method.  The applicable SAE procedures are SAE J1252, SAE J1594, and SAE J2071 (incorporated by reference in §1037.810).  The following modifications apply for SAE J1252:
      (1) The minimum Reynold's number, , is 1.0 ∙10[6] instead of the value specified in section 5.2 of SAE J1252.  Your model frontal area at zero yaw angle may exceed the recommended 5 percent of the active test section area, provided it does not exceed 25 percent.
      (2) For full-scale wind tunnel testing, use good engineering judgment to select a test article (tractor and trailer) that is a reasonable representation of the test article used for the reference method testing.  For example, where your wind tunnel is not long enough to test the tractor with a standard 53 foot trailer, it may be appropriate to use shorter box trailer.  In such a case, the correlation developed using the shorter trailer would only be valid for testing with the shorter trailer.
      (3) For reduced-scale wind tunnel testing, a one-eighth (1/8th) or larger scale model of a heavy-duty tractor and trailer must be used, and the model must be of sufficient design to simulate airflow through the radiator inlet grill and across an engine geometry representative of those commonly used in your test vehicle.
   (b) You must perform wind tunnel testing and the coastdown procedure on the same tractor model and provide the results for both methods.  The wind tunnel tests performed under this section must simulate a vehicle speed of 55 mph.  For Phase 1 vehicles, conduct the wind tunnel tests at a zero yaw angle and, if so equipped, utilizing the moving/rolling floor (i.e., the moving/rolling floor should be on during the test, as opposed to static) for comparison to the coastdown procedure, which corrects to a zero yaw angle for the oncoming wind.  For Phase 2 vehicles, conduct the wind tunnel tests by measuring the drag area according to §1037.525(d)(1) and, if so equipped, utilizing the moving/rolling floor (i.e., the moving/rolling floor should be on during the test, as opposed to static) for comparison to the coastdown procedure.
   (c) Include the following information in your request to use wind-tunnel testing:
      (1) Identify the name and location of the test facilities for your wind tunnel method.  Also include the following things to describe the test facility:
      (2) Background/history.
      (3) The layout (with diagram), type, and construction (structural and material) of the wind tunnel.
      (4) Wind tunnel design details:  corner turning vane type and material, air settling, mesh screen specification, air straightening method, tunnel volume, surface area, average duct area, and circuit length.
      (5) Wind tunnel flow quality:  temperature control and uniformity, airflow quality, minimum airflow velocity, flow uniformity, angularity and stability, static pressure variation, turbulence intensity, airflow acceleration and deceleration times, test duration flow quality, and overall airflow quality achievement.
      (6) Test/working section information: test section type (e.g., open, closed, adaptive wall) and shape (e.g., circular, square, oval), length, contraction ratio, maximum air velocity, maximum dynamic pressure, nozzle width and height, plenum dimensions and net volume, maximum allowed model scale, maximum model height above road, strut movement rate (if applicable), model support, primary boundary layer slot, boundary layer elimination method, and photos and diagrams of the test section.
      (7) Fan section description:  fan type, diameter, power, maximum rotational speed, maximum top speed, support type, mechanical drive, and sectional total weight.
      (8) Data acquisition and control (where applicable):  acquisition type, motor control, tunnel control, model balance, model pressure measurement, wheel drag balances, wing/body panel balances, and model exhaust simulation.
      (9) Moving ground plane or rolling road (if applicable):  construction and material, yaw table and range, moving ground length and width, belt type, maximum belt speed, belt suction mechanism, platen instrumentation, temperature control, and steering.
      (10) Facility correction factors and purpose.

§ 1037.531  Using computational fluid dynamics to calculate drag area (CDA).
This sections describes a procedure for using commercially available computational fluid dynamics (CFD) software code to determine CDA values.  For Phase 1 vehicles, conduct the analysis assuming zero yaw angle, and ambient conditions consistent with coastdown procedures.  For Phase 2 vehicles, conduct the analysis using yaw angles according to §1037.525(d)(1), and assuming ambient conditions consistent with coastdown procedures.  For simulating a wind tunnel test, the analysis should accurately model the particular wind tunnel and assume a wind tunnel blockage ratio consistent with SAE J1252 (incorporated by reference in §1037.810), or one that matches the selected wind tunnel, whichever is lower.  For simulation of open road conditions similar to that experienced during coastdown test procedures, the CFD analysis should assume a blockage ratio at or below 0.2 percent.
(a) Take the following steps for CFD code with a Navier-Stokes formula solver:
   (1) Perform an unstructured, time-accurate, analysis using a mesh grid size with total volume element count of at least 50 million cells of hexahedral and/or polyhedral mesh cell shape, surface elements representing the geometry consisting of no less than 6 million elements, and a near-wall cell size corresponding to a y+ value of less than 300, with the smallest cell sizes applied to local regions of the tractor and trailer in areas of high flow gradients and smaller geometry features.
   (2) Perform the analysis with a turbulence model and mesh deformation enabled (if applicable) with boundary layer resolution of +-95 percent. Once result convergence is achieved, demonstrate the convergence by supplying multiple, successive convergence values for the analysis.  The turbulence model may use k-epsilon (k-ε), shear stress transport k-omega (SST k-ω), or other commercially accepted methods.
(b) For Lattice-Boltzman based CFD code, perform an unstructured, time-accurate analysis using a mesh grid size with total surface elements of  at least 50 million cells using cubic volume elements and triangular and/or quadrilateral surface elements with a near wall cell size of no greater than 6 mm on local regions of the tractor and trailer in areas of high flow gradients and smaller geometry features, with cell sizes in other areas of the mesh grid starting at twelve millimeters and increasing in size from this value as the distance from the tractor-trailer model increases.
(c) All CFD analysis should be conducted using the following conditions:
   (1) To determine CDA values for a tractor, test with a tractor-trailer combination using the manufacturer's tractor and a standard trailer.  To determine CDA values for a trailer, test with a tractor-trailer combination using a standard tractor and the manufacturer's trailer.
   (2) An environment with a blockage ratio at or below 0.2 percent to simulate open road conditions, a zero degree yaw angle between the oncoming wind and the tractor-trailer combination.
   (3) Ambient conditions consistent with the coastdown test procedures specified in this part.
   (4) Open grill with representative back pressures based on data from the tractor model,
   (5) Turbulence model and mesh deformation enabled.
   (6) Tires and ground plane in motion consistent with and simulating a vehicle moving in the forward direction of travel.
   (7) The smallest cell size should be applied to local regions on the tractor and trailer in areas of high flow gradients and smaller geometry features (e.g., the a-pillar, mirror, visor, grille and accessories, trailer leading and trailing edges, rear bogey, tires, and tractor-trailer gap).
   (8)  Simulate a speed of 55 mph and, if not available from coastdown test procedures, a wind speed of 7 mph.
(d) You may ask us to allow you to perform CFD analysis using parameters and criteria other than those specified in this section, consistent with good engineering judgment, if you can demonstrate that the specified conditions are not feasible (e.g., insufficient computing power to conduct such analysis, inordinate length of time to conduct analysis, equivalent flow characteristics with more feasible criteria/parameters) or improved criteria may yield better results (e.g., different mesh cell shape and size).  To support this request, we may require that you supply data demonstrating that your selected parameters/criteria will provide a sufficient level of detail to yield an accurate analysis, including comparison of key characteristics between your criteria/parameters and the criteria specified in paragraphs (a) and (b) of this section (e.g., pressure profiles, drag build-up, and/or turbulent/laminar flow at key points on the front of the tractor and/or over the length of the tractor-trailer combination).
(e) Include the following information in your request to determine CDA values using CFD:
   (1) Official name/title of the software product.
   (2) Date and version number for the software product.
   (3) Manufacturer/company name, address, phone number and web address for software product.
   (4) Identify if the software code is based on Navier-Stokes or Lattice-Boltzmann equations.

§ 1037.533  Constant-speed procedure for for calculating drag area (CDA).
This section describes how to use constant-speed aerodynamic drag testing to determine CDA.  The constant speed test requires that the driving torque, vehicle speed, air flow velocity, and yaw angle be measured at two different constant vehicle speeds under defined conditions on a test track.
(a) Test track. Set up your test track or road to meet the requirements in § 1037.527(b)(1)(ii).  The length of the track or road must be at least 1 mile.
(b) Vehicle torque and speed variation thresholds.  Vehicles must meet the following speed and torque variation limits during constant speed drag testing:
    (1) High speed test.
       (i) Speed variation limit:

       Where:
       = mean vehicle speed averaged over 10 second increments in the measurement section in km/h.
       = 1 second moving average of vehicle speed in km/h.
       (ii) Torque variation limit:

       Where:
       = Tsum average 10 second increments in the measurement section in Nm.
       Tsum = sum of corrected torque values from the left and right wheels in Nm.
       = 1 second moving average of Tsum in Nm.
    (2) Low speed test.
       (i) Speed variation limit:

       Where:
       = mean vehicle speed over 10 second increments in the measurement section in km/h.
       = 1 second moving average of vehicle speed in km/h.
        (ii) Torque variation limit:

       Where:
       = Tsum average per Xms second increments in the measurement section in Nm.
       Tsum = sum of corrected torque values from all wheels in Nm.
       = Xms second moving average of Tsum in Nm.
(c) Ambient conditions.  (1) The ambient conditions described in Section 7.1 through 7.4 of SAE J1263 (incorporated by reference in § 1037.810) must be met over the course of testing.
    (2) The road surface temperature must be <= 50 °C.  Use good engineering judgment to take a representative measurement of road surface temperature either directly or using a radiation thermometer.
(d) Vehicle setup and requirements.  Set up the vehicle for testing as described in § 1037.527. The trailer must meet specifications given in § 1037.501(g).
    (1) Verify that the axle alignment is within the manufacturer specifications.
    (2) The wheels must rotate freely. Verify that there is no inadvertent brake drag after the vehicle is instrumented.
(e) Measurement instrument calibration and verification.  Measurement instruments must meet the requirements of 40 CFR part 1065 subpart C.  Calibrate and verify measurement instruments according to 40 CFR part 1065 subpart D.
    (1) Torque.  Measure direct torque at all driven axles using one of the following measurement systems:
       (i) Hub torque meter.
       (ii) Rim torque meter.
       (iii) Half shaft torque meter.
       (iv) Driveshaft torque meter.
    (2) Measure the rotational speed where the torque is measured.  This can be calculated using the engine speed data collected from the CAN in conjunction with the transmission gear ratio and rear axle ratio, where applicable.
    (3) Gather vehicle speed at 10 Hz, in conjunction with time-of-day data, at the resolution and accuracy described in Section 5.3 of SAE J2263 (incorporated by reference in § 1037.810).
    (4) Collect wind speed, wind direction, air temperature, and air pressure data as described in § 1037.527(b)(3).
    (5) Mount an anemometer at the leading edge of the trailer approximately 1 meter above the top of the trailer to collect air speed and air direction data onboard the vehicle at 10 Hz, in conjunction with time-of-day data.
       (i) For air speeds in the range of 20  -  33 m/s and yaw angles in the range of 0 +-7 degrees, the anemometer must meet the following accuracy specifications:
           (A) Air speed: +- 2 % of actual reading.
           (B) Yaw angle: +- 1 degree.
       (ii) Align the anemometer using geometrical and optical aids.  After aligning the instrument, evaluate the misalignment of the installation to enable correction during the data processing.
    (6) Use a CAN-bus signal recorder that is capable of reading and recording the vehicle CAN-bus signals.
(f) Measurement signals and data recording. [Reserved].
(g) Test procedure.  The constant speed vehicle test is conducted by targeting the maximum vehicle velocity span between the measurement of mechanical resistance (low speed) and total running resistance (high speed).
    (1) Vehicle speed must meet the speed variation thresholds in paragraph (b) of this section.  The target speeds for the tests are as follows:
       (i)  Low speed testing, constant velocity of 10 mph.
       (ii) High speed testing, constant velocity of 50 mph.
       (iii) High speed testing, constant velocity of 70 mph.
    (2) Perform testing as follows:
       (i) Install the torque meters on the driven axles of the test vehicle, or on the driveshaft if using a driveshaft torque meter.
       (ii) Check the drive-wheels for proper rotation, with torque meters and half shafts installed, by manually rotating the wheels with the wheels off of the ground.
       (iii) Measure the total mass of the vehicle with an accuracy that meets the requirements in Section 5.9 of SAE J2263.
       (iv) Inflate the tires as described in Section 8.1 of SAE J2263.
       (v) Start the engine to pre-condition the vehicle by idling without the parking brake applied.
       (vi) If you have instrumented the vehicle with rim torque meters, lift the instrumented axle and zero the torque meters.
       (vii) Condition the vehicle as described in Section 8.3 of SAE J2263.
       (viii) If you have instrumented the vehicle with hub or shaft torque meters, bring the vehicle to a standstill on the selected standstill area of the test track.  Slow the vehicle down carefully and allow it to roll to a stop with the clutch disengaged or transmission in neutral and engine switched off.  Zero the torque meters within a minute of coming to a stop.  Continue to warm-up the vehicle for at least 2 km after the standstill phase is complete.
       (ix) Perform the drive speed tests by holding the drive speed constant in the stabilization and measurement sections.  Multiple passes may be performed to reach the amount of test time required.  For stabilization, drive the vehicle at the target speed for 200 meters before the measurement section for each speed and direction, including before each pass if multiple passes are needed.  When driving the vehicle through the measurement section, it must be driven straight without steering.  Perform and collect data for the drive speed tests as follows:
          (A) Collect 10 mph data for five minutes in each direction.
          (B) Collect 50 mph data for 7.5 minutes in each direction.
          (C) Collect 70 mph data for 15 minutes in each direction.
          (D) Collect 50 mph data for 7.5 minutes in each direction.
          (E) Collect 10 mph for five minutes in each direction.
       (x) Perform a post test drift check of the torque meters using one of the following procedures:
          (A) Axle lift.  If you have instrumented the vehicle with rim torque meters, lift the instrumented axle and zero the torque meters.  Record the signals of all torque meters for at least 30 seconds.
          (B) Coastdown.  If you have instrumented the vehicle with hub or shaft torque meters, bring the vehicle to a standstill on the selected standstill area of the test track.  Slow the vehicle down carefully and allow it to roll to a stop with the clutch disengaged or transmission in neutral and engine switched off.  Record the signals of all torque meters for at least 30 seconds.
          (C) Validation.  Torque meter drift must be <= 3.0 Nm.  If the drift exceeds this limit, then the test results are not valid and you must retest the vehicle.
       (xi) Perform the following general checks during the test:
          (A) Verify that the axle/wheel bearings are not overheating during the test using a hand-held infrared thermometer.
          (B) Recheck the vehicle configuration upon the completion of testing.  Note any differences in the vehicle or equipment setup, etc.
(h) Testing documentation.  In addition to the recording measurement data, document the testing by providing us with the following data:
    (1) A general description and pictures of the vehicle tested.
    (2) Vehicle maximum height and width.
    (3) Mileage at each step of the testing.
    (4) The following start times: warm-up phase, low-speed tests, and high-speed tests.
    (5) Vehicle fuel level and the amount of fuel added over the course of testing including the date, time, and mileage at the refuel point.
    (6) Number of vehicle occupants (if applicable: time and detail of changes).
    (7) Actual total vehicle mass (including mileage readings, occupants, and fuel level).
    (8) Timing of torque meter zeroing and drift check.
    (9) Test track type and driving direction for each data set.
    (10) Test track temperatures, if applicable.
    (11)  Documentation of extraordinary events, for example:
       (i) Close passing of another vehicle.
       (ii) Driving errors.
       (iii) Technical errors.
       (iv) Measurement errors.
    (12) Transmission gear utilized for the low speed test and high speed tests.
       (i) Calculations.  Time align all data.  Use the following calculations to determine constant speed aerodynamic drag:
       (1) Onboard air speed.  Correct the mobile anemometer air speed signal for instrument error, position error, and boundary layer effects using the calibration test data results in paragraph (e) of this section as follows:
           (i) Using the data generated, average the vehicle speed, v, air speed, vair,meas, wind speed, w, and wind direction, θw measurements over 10 second increments for each coastdown.
           (ii) Calculate the theoretical air speed for each 10 second increment from the vehicle speed, wind speed, and wind direction averages using the following equation:

           		Eq. 1037.533-1
           Where:
= the mean vehicle speed over the 10 second increment.
           = the mean wind speed over the 10 second increment.
           = the mean wind direction over the 10 second increment, counterclockwise relative to the air flow in travel direction 1.  For example, if the vehicle is traveling eastbound in direction 1, then = 0° means a wind from the west, = 90° means a wind from the north, and =  - 90° means a wind from the south, and = +-180° means a wind from the east.
           (iii) Plot all of the 10 second calculations of theoretical air speed, , versus the 10 second means of measured air speed, , to determine the air speed correction coefficients, intercept α0 and linear α1, based on the following equation:

                       Eq. 1037.533-2

           (iv) Correct the raw air speed measurements using the following equation:

                       Eq. 1037.533-3
       (2) Yaw angle.  Correct the mobile anemometer air angle signal for instrument error, misalignment error, position error, and boundary layer effects as follows:
           (i) Using the data generated, average the air speed, vair, wind speed, w, and wind direction, θw measurements over 10 second increments for each coastdown.
           (ii) Calculate the theoretical air direction for each 10 second increment using the following equation.

              (B) Plot all of the 10 second calculations of theoretical air direction, , versus the 10 second means of measured air direction, , to determine the air direction correction coefficients, intercept β0 and linear β1, based on the following equation:

		Eq. 1037.533-4
              (C) Correct the raw air speed measurements using the following equation:

		Eq. 1037.533-5
       (3) Torque.  Correct torque measurement(s) for instrument error as follows:

       		Eq. 1037.533-6
       Where:
       T = corrected torque.
       Tr = torque meter reading.
       fTie = torque meter instrument error correction factor.
       fTd = torque meter drift correction factor.
       (4) Calculation of traction force.  Calculate traction force using the following equation:

       		Eq. 1037.533-7
       Where:
       Ftrac[speed] = traction force at the test speed.
       Ttotal[speed] = sum of all corrected torques at the test speed.
       neng = engine speed in rpm.
       igear = transmission ratio of engaged gear.
       iaxle = axle transmission ratio.
       vveh = vehicle speed.

       Average the Ftrac[speed] for each of the test speeds over 10 second increments.

       (5) Determination of drag area, CDA.  Calculate the CDA value for zero cross-wind conditions using the recorded data for traction force, air speed, and yaw angle using the following equations:
           (i) Calculate aerodynamic forces, Faero50 and Faero70, for every 10 second segment by subtracting the average low-speed traction force, F10avg, from the 10 second average high-speed traction force, F[speed]avg, for both the 50 mph and 70 mph runs, F[speed].
           Faero[speed] = F[speed]avg  -  F10avg
           		Eq. 1037.533-8
           (ii) Calculate the mean air density using the following equation:

                 	Eq. 1037.533-9
           Where:
            = mean air density in kg/m[3].
            = mean air pressure in kPa.
            = mean air temperature in °C.
           R = molar gas constant = 287.058 J/(kg·K).

           (iii) Average the corrected air speed and corrected yaw angle over every 10 second segment from the high-speed data to determine and .
           (iv) Calculate CDA using the following equation:

                 	Eq. 1037.533-10
           Where:
           Faero[speed] = aerodynamic force at 50 or 70 mph for every 10 second segment.

          (D) If less than 75 percent of the 10-second averages of corrected yaw angle, , are between -2 and 2 degrees, then plot all of the 10-second calculations of CDA versus the 10 second averages of corrected yaw angle, , to determine zero-yaw drag area CDA(0) using the following fourth-order polynomial regression equation:

          		Eq. 1037.533-11

          If 75 percent or more of the 10-second averages of corrected yaw angle, , are between -2 and 2 degrees, then determine zero-yaw drag area, CDA(0), by averaging the 10-second calculations of CDA where -2° < < 2°.

§ 1037.540  Special procedures for testing vehicles with hybrid power take-off.
This section describes the procedure for quantifying the reduction in greenhouse gas emissions for vehicles as a result of running power take-off (PTO) devices with a hybrid energy delivery system.  The procedures are written to test the PTO by ensuring that the engine produces all of the energy with no net change in stored energy.  The full test for the hybrid vehicle is from a fully charged renewable energy storage system (RESS) to a depleted RESS and then back to a fully charged RESS.  These procedures may be used for testing any hybrid architecture for which you are requesting a vehicle certificate using either chassis testing or powertrain testing.  You must include all hardware for the PTO system.  You may ask us to modify the provisions of this section to allow testing hybrid vehicles other than electric-battery hybrids, consistent with good engineering judgment.
(a) Select two vehicles for testing as follows:
   (1) Select a vehicle with a hybrid energy delivery system to represent the vehicle family.  If your vehicle family includes more than one vehicle model, use good engineering judgment to select the vehicle type with the maximum number of PTO circuits that has the smallest potential reduction in greenhouse gas emissions.
   (2) Select an equivalent conventional vehicle as specified in §1037.615.
(b) Measure PTO emissions from the fully warmed-up conventional vehicle as follows:
   (1) Without adding any additional restrictions, instrument the vehicle with pressure transducers at the outlet of the hydraulic pump for each circuit.
   (2) Operate the PTO system with no load for at least 15 seconds.  Measure the pressure and record the average value over the last 10 seconds ().  Apply maximum operator demand to the PTO system until the pressure relief valve opens and pressure stabilizes; measure the pressure and record the average value over the last 10 seconds ().
   (3) Denormalize the PTO duty cycle in Appendix II of this part using the following equation:

   Where:
   prefi = the reference pressure at each point i in the PTO cycle.
   NPi = the normalized pressure at each point i in the PTO cycle.
    = the mean maximum pressure measured in paragraph (b)(2) of this section.
    = the mean minimum pressure measured in paragraph (b)(2) of this section.

   (4) If the PTO system has two circuits, repeat paragraph (b)(2) and (3) of this section for the second PTO circuit.
   (5) Install a system to control pressures in the PTO system during the cycle.
   (6) Start the engine.
   (7) Operate the vehicle over one or both of the denormalized PTO duty cycles in Appendix II of this part, as applicable.  Measure emissions during operation over each duty cycle using the provisions of 40 CFR part 1066.
   (8) For each duty cycle, validate the pressure in each circuit with the pressure specified from the cycle according to 40 CFR 1065.514.  Measured pressures must meet the specifications in the following table for a valid test:
    Table 1 of §1037.540  -  Statistical criteria for validating duty cycles
                                   Parameter
                                   Pressure
                                  Slope, a1
                           0.950 < a1 < 1.030
                       Absolute value of intercept, |a0|
                     < 2.0 % of maximum mapped pressure
                       Standard error of estimate, SEE
                     < 10 % of maximum mapped pressure
                      Coefficient of determination, r[2]
                                  > 0.970

(c) Measure PTO emissions from the fully warmed-up hybrid vehicle as follows:
   (1) Perform the steps in paragraphs (b)(1) through (5) of this section.
   (2) Prepare the vehicle for testing by operating it as needed to stabilize the battery at a full state of charge.  For electric hybrid vehicles, we recommend running back-to-back PTO tests until engine operation is initiated to charge the battery.  The battery should be fully charged once engine operation stops.  The ignition should remain in the "on" position.
   (3) Turn the vehicle and PTO system off while the sampling system is being prepared.
   (4) Turn the vehicle and PTO system on such that the PTO system is functional, whether it draws power from the engine or a battery.
   (5) Operate the vehicle over one or both of the denormalized PTO duty cycles without turning the vehicle off, until the engine starts and then shuts down.  The test cycle is completed once the engine shuts down.  Measure emissions as described in paragraph (b)(7) of this section.  Use good engineering judgment to minimize the variability in testing between the two types of vehicles.
   (6) Refer to paragraph (b)(8) of this section for cycle validation.
(d) Calculate the equivalent distance driven based on operating time for the PTO portion of the test by determining the time of the test (hours) and applying the conversion factor in paragraph (d)(4) of this section.  For testing where fractions of a cycle were run (for example, where three cycles are completed and the halfway point of a fourth PTO cycle is reached before the engine starts and shuts down again), use the following procedures to calculate the time of the test:
   (1) Add up the time run for all complete tests, in hours.
   (2) For fractions of a test, use the following equation to calculate the time:

   Where:
   ttest = time of the incomplete test, in hours.
   i = measurement interval number.
   N = number of measurement intervals.
   NPcircuit_1 = normalized pressure command from circuit 1 of the PTO cycle.
   NPcircuit_2 = normalized pressure command from circuit 2 of the PTO cycle.  Let NPcircuit_2 = 1 if there is only one circuit.
   tcycle = time of a complete cycle, in hours.
   (3) Sum the time from complete cycles and from partial cycles.
   (4) Divide the total PTO operating time from paragraph (d)(3) of this section by a conversion factor of 0.0144 hr/mi to determine the equivalent distance driven.  This is based on an assumed fraction of engine operating time during which the PTO is operating of 28 percent, and an assumed average vehicle speed while driving of 27.1 mph, as follows:

(e) For Phase 1, calculate combined cycle-weighted emissions of the four duty cycles for vocational vehicles as follows:
   (1) Calculate the CO2 emission rates in grams per test without rounding.
   (2) Divide the CO2 mass from the PTO cycle by the distance determined in paragraph (d)(4) of this section and the standard payload to get the CO2 emission rate in g/ton-mile.
   (3) Calculate the g/ton-mile emission rate for the driving portion of the test specified in §1037.510 and add this to the CO2 g/ton-mile emission rate for the PTO portion of the test.
   (4) Follow the provisions of §1037.615 to calculate improvement factors and benefits for advanced technologies.
(f) For Phase 2, calculate the delta PTO emission results for input into GEM during vehicle certification as follows:
   (1) Calculate CO2 emission rates in grams per test, mCO2PTO, without rounding, as described in § 1037.550(k)(1).
   (2) Correct the result from paragraph (f)(1) of this section for the test fuel's mass-specific net energy content as described in 40 CFR 1036.530(b).  Divide the resulting corrected CO2 mass by the distance determined in paragraph (d)(4) of this section and the standard payload to determine the CO2 emission rate in g/ton-mile.
   (3) Calculate the difference between the conventional PTO emissions result and the hybrid PTO emissions result for input into GEM.

§ 1037.550 Powertrain testing.
This section describes the procedure for simulating a chassis test for both conventional and hybrid powertrains.  This testing is an optional approach that replaces the default fuel map in GEM for certifying Phase 2 vehicles.  It applies for vehicle manufacturers, but engine manufacturers may perform testing under this section as specified in 40 CFR 1036.630.  While this section includes the detailed equations you need to develop your own driver model and vehicle model, we recommend that you use the MATLAB/Simulink code provided at www.epa.gov/otaq/climate/gem.htm.
(a) Perform the powertrain test to establish measured CO2 emission rates at a range of speed and load settings.  Also measure NOx emissions (in g) during each of the specified sampling periods.  This section uses engine parameters and variables that are consistent with 40 CFR part 1065.  For molar mass values, see 40 CFR 1065.1005(f)(2).
(b) Select numerical values to characterize the powertrain emissions at each setting.  The selected values may not be lower than any corresponding measured values determined in this section.  You may select any value that is at or above the corresponding measured value.  These selected emission rates serve as worst-case values for certification.  Your declared emission rates are analogous to Family Emission Limits; these values serve as standards (or limit values), which means that a powertrain exceeding its declared CO2 emission level at any point is considered noncompliant.
(c) Select a test engine and powertrain as described in §1037.235.
(d) Set up the engine according to 40 CFR 1065.110.  The default test configuration involves connecting the powertrain's transmission output shaft directly to the dynamometer.  You may instead set up the dynamometer to connect at the wheel hubs if your powertrain configuration requires it, such as for hybrid powertrains.
(e) Cool the powertrain during testing so temperatures for intake-air, oil, coolant, block, head, transmission, battery, and power electronics are within their expected ranges for normal operation.  You may use auxiliary coolers and fans.
(f) Set the dynamometer to operate in speed control.  Record data as described in 40 CFR 1065.202.  Design a vehicle model to measure torque and calculate the dynamometer speed setpoint at a rate of at least 100 Hz, as follows:
    (1) Calculate the dynamometer's angular speed target, fnref,dyno, based on the simulated linear speed of the tires:

       	Eq. 1037.550-1
       Where:

       	Eq. 1037.550-2
       kd = axle ratio.  Set kd = 4.0 for all calculations in this section.
       ktopgear = transmission ratio in the highest available gear.
       v65 = reference speed.  Use 65 mph = 29.05 m/s.
       fn[speed] = engine's angular speed determined in paragraph (h) of this section.
       	Eq. 1037.550-3
       Where:
       vrefi = simulated vehicle reference speed.  Use unrounded result.
       i= a time-based counter corresponding to each measurement during the sampling period.  Let vref1=0; start calculations at i=2.  A 10-minute sampling period will generally involve 60,000 measurements.
       T = instantaneous measured torque.
       Effaxle = axle efficiency.  Use Effaxle = 0.955 for T > 0, and use Effaxle = 1/0.955 for T < 0.  To calculate fnrefi,dyno for a dynamometer connected at the wheel hubs, as described in paragraph (f)(2) of this section, use Effaxle = 1.0.
       M = vehicle mass for a vehicle class as determined in paragraph (h) of this section.
       g = gravitational acceleration.  Use g = 9.81 m/s[2].
       Crr = coefficient of rolling resistance for a vehicle class as determined in paragraph (h) of this section.
       Gi-1 = the percent grade interpolated at distance, Di-1 from the duty cycle in Appendix IV corresponding to measurement (i-1).

       	Eq. 1037.550-4
        = air density at reference conditions. Use  = 1.17 kg/m[3].
       CDA = drag area for a vehicle class as determined in paragraph (h) of this section.
       Fbrake = instantaneous braking force applied by the driver model.

       	Eq. 1037.550-5
       Δt = the time interval between measurements as measured by the test cell host computer; for example at 100 Hz this would be equal to 0.0100 seconds.
       Mrotating = inertial mass of rotating components as determined in paragraph (h) of this section.

       Example:
       Example is for Class 2b to 7 vocational vehicles with 6 speed automatic transmission at B speed (Test 4 in Table 1 of § 1037.550).
       kd = 4.0
       ktopgear = 0.6716
       fnrefB = 1870 rpm = 31.16 r/s
       v65 = 65 mph = 29.05 m/s
       T1000-1 = 500.0 Nm
       Crr = 6.9 kg/ton = 6.9∙10[-3] kg/kg
       M = 11408 kg
       CDA = 5.4 m[2]
       G1000-1 = 1.0% = 0.018

       Δt = 0.0100 s
       Mrotating = 454 kg

       vref1000 = 20.00128 m/s

   (2) For testing with the dynamometer connected at the wheel hubs, calculate fnref,dyno using the following equation:

      	Eq. 1037.550-6
(g) Design a driver model to mimic a human driver modulating the throttle and brake pedals to follow the test cycle as closely as possible.  The driver model must meet the requirements of § 1037.510 for steady-state testing and 40 CFR 1066.425(e) for transient testing.  Design the driver model to meet the following specifications:
   (1) Send a brake signal when throttle position is zero and vehicle speed is greater than the reference vehicle speed from the test cycle.  Include a delay before changing the brake signal to prevent dithering, consistent with good engineering judgment.
   (2) Allow braking only if throttle position is zero.
   (3) Compensate for the distance driven over the duty cycle over the course of the test. Use the following equation to perform the compensation in real time to determine your time in the cycle:

   	Eq. 1037.550-7
   Where:
   vvehicle = measured vehicle speed.
   vcycle = reference speed from the test cycle.  If vcycle,i-1 < 1.0 m/s, set vcycle,i-1 = vvehicle,i-1.

(h) Set up the driver model and the vehicle model in the test cell to test the powertrain, as follows:
   (1) For Class 2b through Class 7 vehicles, test the powertrain over eight different test runs.  For all test runs, set Mrotating to 454 kg, CDA to 5.4, kd to 4.0, and Effaxle to 0.955.   Set the tire radius, r, for each test run based on the vehicle configuration corresponding to the designated engine speed (A, B, C, or fntest, all from 40 CFR part 1065) at 65 mph.  These engine speeds apply equally for spark-ignition engines.  Use the following settings specific to each test run:

   Table 1 of § 1037.550  -  Vehicle Settings for Powertrain Testing of Class 2b through Class 7 Vehicles

                                    Test 1
                                    Test 2
                                    Test 3
                                    Test 4
                                    Test 5
                                    Test 6
                                    Test 7
                                    Test 8
                                    M (kg)
                                     7,257
                                    11,408
                                     7,257
                                    11,408
                                     7,257
                                    11,408
                                     7,257
                                    11,408
                                 Crr (kg/ton)
                                      6.7
                                      6.9
                                      6.7
                                      6.9
                                      6.7
                                      6.9
                                      6.7
                                      6.9
                               r at engine speed
                                       A
                                       A
                                       B
                                       B
                                       C
                                       C
                              Maximum test speed
                              Maximum test speed

   (2) For Class 8 vehicles, test the powertrain over nine different test runs.  For all test runs, set Crr to 6.9, kd to 4.0, and Effaxle to 0.955.  Set the tire radius, r, for each test run based on the vehicle configuration corresponding to the designated engine speed (the minimum NTE exclusion speed as determined in 40 CFR 86.1370(b)(1), B, or fntest from 40 CFR part 1065) at 65 mph.  Use the settings specific to each test run from Table 2 of this section for general purpose vehicles, and from Table 3 of this section for heavy-haul tractors.  Tables 2 and 3 follow:

Table 2 of § 1037.550  -  Vehicle Settings for Powertrain Testing of Class 8 Vehicles  -  General Purpose Vehicles

                                    Test 1
                                    Test 2
                                    Test 3
                                    Test 4
                                    Test 5
                                    Test 6
                                    Test 7
                                    Test 8
                                    Test 9
                                    M (kg)
                                    31,978
                                    22,679
                                    19,051
                                    31,978
                                    22,679
                                    19,051
                                    31,978
                                    22,679
                                    19,051
                                      CDA
                                      5.4
                                      4.7
                                      4.0
                                      5.4
                                      4.7
                                      4.0
                                      5.4
                                      4.7
                                      4.0
                                Mrotating (kg)
                                     1,134
                                      907
                                      680
                                     1,134
                                      907
                                      680
                                     1,134
                                      907
                                      680
                               r at engine speed
                          Minimum NTE exclusion speed
                          Minimum NTE exclusion speed
                          Minimum NTE exclusion speed
                                       B
                                       B
                                       B
                              Maximum test speed
                              Maximum test speed
                              Maximum test speed

Table 3 of § 1037.550  -  Vehicle Settings for Powertrain Testing of Heavy-Haul Tractors

                                    Test 1
                                    Test 2
                                    Test 3
                                    Test 4
                                    Test 5
                                    Test 6
                                    Test 7
                                    Test 8
                                    Test 9
                                    M (kg)
                                    40,895
                                    31,978
                                    22,679
                                    40,895
                                    31,978
                                    22,679
                                    40,895
                                    31,978
                                    22,679
                                      CDA
                                      6.1
                                      5.4
                                      4.7
                                      6.1
                                      5.4
                                      4.7
                                      6.1
                                      5.4
                                      4.7
                                Mrotating (kg)
                                     1,134
                                      907
                                      680
                                     1,134
                                      907
                                      680
                                     1,134
                                      907
                                      680
                               r at engine speed
                          Minimum NTE exclusion speed
                          Minimum NTE exclusion speed
                          Minimum NTE exclusion speed
                                       B
                                       B
                                       B
                              Maximum test speed
                              Maximum test speed
                              Maximum test speed

(i) Operate the powertrain over each of the duty cycles specified in § 1037.510(a)(2).
(j) Collect and measure emissions as described in 40 CFR part 1065.  For hybrid powertrains, correct for the net energy change of the energy storage device as described in 40 CFR 1066.501.
(k) For each test point, validate the measured output speed with the corresponding reference values.  You may delete points when the vehicle is stopped.  For steady-state tests (55 mph cruise, 65 mph cruise, and idle), apply cycle-validation criteria by treating the sampling periods from the three tests as a continuous sampling period.  Perform this validation based on the following parameters:

Table 4 of § 1037.550  -  Statistical criteria for validating duty cycles
                                   Parameter
                                 Speed Control
Slope, a1
                           0.990 < a1 < 1.010
Absolute value of intercept, |a0|
                       < 2.0 % of maximum test speed
Standard error of estimate, SEE
                       < 2.0 % of maximum test speed
Coefficient of determination, r[2]
                                  > 0.990

(l) [Reserved]
(m) Calculate mass of fuel consumed for all duty cycles except idle as follows:
   (1) For measurements involving measured fuel mass flow rate, calculate the mass of fuel for each duty cycle, mfuel[cycle], as follows:

   	Eq. 1037.550-8

   Where:
   N = total number of measurements over the duty cycle.  For batch fuel mass measurements, set N = 1.
   i = an indexing variable that represents one recorded value.
    = the fuel mass flow rate, for each point, i, starting from i = 1.
   ∆t = 1/frecord
   frecord = the data recording frequency.

   Example:
   N = 6680
    = 1.856 g/s
    = 1.962 g/s
   frecord = 10 Hz
   t = 1/10 = 0.1 s

   mfueltransient = 111.95 g

   (2) For measurements that do not involve measured fuel mass flow rate, calculate the mass of fuel for each duty cycle, mfuel[cycle], as follows:
      (i) For calculations that use continuous measurement of emissions and CO2 from urea, calculate mfuel[cycle] using the following equation:

      			Eq. 1037.550-9
      Where:
      N[event] = total number of measurements over the duty cycle.
      i = an indexing variable that represents one recorded emission value.
      wCref = reference carbon mass fraction of fuel as given in Table 1 of 40 CFR 1036.530.
      = exhaust molar flow rate from which you measured emissions.
      = amount of carbon from fuel in the exhaust per mole of dry exhaust.
      = amount of H2O in exhaust per mole of exhaust.
      j = an indexing variable that represents one recorded mass emission rate of CO2 from urea value.
      = mass emission rate of CO2 from the contribution of urea decomposition over the duty cycle as determined from 40 CFR 1036.535(a)(8).  If your engine does not utilize urea SCR for emission control, or if you choose not to perform this correction, set this value equal to 0.

      Example:
      MC = 12.0107 g/mol
      wCmeas = 0.867
      Nemission = 6680
      NCO2urea = 668
       = 2.876 mol/s
       = 2.224 mol/s
       = 2.61∙10[-3] mol/mol
      = 1.91∙10[-3] mol/mol
      = 3.53∙10[-2] mol/mol
      = 3.13∙10[-2] mol/mol
      frecord-emission = 10 Hz
      temission = 1/10 = 0.1 s
      MCO2 = 44.0095 g/mol
      frecord-CO2urea = 1 Hz
      tCO2urea = 1/1 = 1.0 s
      = 0.0726 g/s
      = 0.0751 g/s

      mCO2transient = 1619.6 g
      (ii) If you measure batch emissions, calculate mfuel[cycle] using the following equation:

      			Eq. 1037.550-10
      (iii) If you measure continuous emissions and batch CO2 from urea, calculate mfuel[cycle] using the following equation:

   			Eq. 1037.550-11
      (iv) If you measure batch emissions and batch CO2 from urea, calculate mfuel[cycle] using the following equation:

   			Eq. 1037.550-12

(n) Determine the mass of CO2 emissions at idle as follows:
   (1) Measure fuel consumption with a fuel flow meter and report the mean fuel mass flow rate for each duty cycle, .
   (2) For measurements that do not involve measured fuel mass flow rate, calculate the fuel mass flow rate for each duty cycle, , for each set of vehicle settings, as follows:

   Eq. 1037.550-13
   Where:
   = the mean raw exhaust molar flow rate from which you measured emissions.
   = mass emission rate of CO2 from the contribution of urea decomposition over the duty cycle as determined from 40 CFR 1036.535(a)(8), for each point, i, starting from i = 1.  If your engine does not utilize urea SCR for emission control, or if you choose not to perform this correction, set this value equal to 0.

   MC = molar mass of carbon.
   wCmeas = carbon mass fraction of fuel as determined by 40 CFR 1065.655(d), except that you may not use the default properties in Table 1 of 40 CFR 1065.655 to determine α, , and wC for liquid fuels.
   = the mean raw exhaust molar flow rate from which you measured emissions according to 40 CFR 1065.655.
   = the mean concentration of carbon from fuel in the exhaust per mole of dry exhaust.
   = the mean concentration of H2O in exhaust per mole of dry exhaust.
   = the mean CO2 mass emission rate from urea decomposition as described in paragraph (c)(9) of this section.  If your engine does not utilize urea SCR for emission control, or if you choose not to perform this correction, set equal to 0.
   MCO2 = molar mass of carbon dioxide.

   Example:
   MC = 12.0107 g/mol
   wCmeas = 0.867
   = 25.534 mol/s
   = 2.805∙10[-3] mol/mol
   = 3.53∙10[-2] mol/mol
   = 0.0726 g/s
   MCO2 = 44.0095

   = 0.405 g/s = 1458.6 g/hr
(o) Include outputs in Table 5 as follows:
   (1) Your declared valued for CO2 emissions, as described in paragraph (b) of this section.  For idle, declare a CO2 mass emission rate, .  For all other cycles, declare CO2 mass emissions, mCO2[cycle], for each duty cycle.
   (2) Powertrain output speed per unit of vehicle speed.
      (i) For dynamometers connected at the transmission output shaft:

      (ii) For dynamometers connected at the wheel hubs:

   (3) Positive work, W[cycle]powertrain, over the duty cycle at the transmission output or wheel hubs from the powertrain test.

      Table 5 of § 1037.550  -  Example test result output matrix for Class 8 vehicles.

                                    Test 1
                                    Test 2
                                    Test 3
                                    Test 4
                                    Test 5
                                    Test 6
                                    Test 7
                                    Test 8
                                    Test 9

                              W[cycle]powertrain

(p) Correct each result from paragraph (l)(1) of this section for the test fuel's mass-specific net energy content as described in paragraph of § 1036.530(b)(3).
(q) For each test, record the engine speed and torque as defined in 40 CFR 1065.915(d)(5) with a minimum sampling frequency of 1 Hz.  These engine speed and torque values represent a duty cycle that can be used for separate testing with an engine mounted on an engine dynamometer, such as for a selective enforcement audit as described in §1037.301.

§ 1037.555 Special procedures for testing Phase 1 post-transmission hybrid systems.
This section describes the procedure for simulating a chassis test with a pre-transmission or post-transmission hybrid system for A to B testing.  These procedures may also be used to perform A to B testing with non-hybrid systems.
(a) Set up the engine according to 40 CFR 1065.110 to account for work inputs and outputs and accessory work.
(b) Collect CO2 emissions while operating the system over the test cycles specified in §1037.510(a)(1).
(c) Collect and measure emissions as described in 40 CFR part 1066.  Calculate emission rates in grams per ton-mile without rounding.  Determine values for A, B, C, and M for the vehicle being simulated as specified in 40 CFR part 1066.  If you will apply an improvement factor or test results to multiple vehicle configurations, use values of A, B, C, M, kd, and r that represent the vehicle configuration with the smallest potential reduction in greenhouse gas emissions as a result of the hybrid capability.
(d) Calculate the transmission output shaft's angular speed target for the driver model, fnref,driver, from the linear speed associated with the vehicle cycle using the following equation:

      Eq. 1037.555-1
Where:
vcyclei = vehicle speed of the test cycle for each point, i, starting from i=1.
kd = final drive ratio (the angular speed of the transmission output shaft divided by the angular speed of the drive axle), as declared by the manufacturer.
r = radius of the loaded tires, as declared by the manufacturer.
(e) Use speed control with a loop rate of at least 100 Hz to program the dynamometer to follow the test cycle, as follows:
   (1) Calculate the transmission output shaft's angular speed target for the dynamometer, fnref,dyno, from the measured linear speed at the dynamometer rolls using the following equation:

      Eq. 1037.555-2
   Where:

      Eq. 1037.555-3
   T = instantaneous measured torque at the transmission output shaft.
   Fbrake = instantaneous brake force applied by the driver model to add force to slow down the vehicle.
   t = elapsed time in the driving schedule as measured by the dynamometer, in seconds.
   (2) For each test, validate the measured transmission output shaft's speed with the corresponding reference values according to 40 CFR 1065.514(e). You may delete points when the vehicle is stopped.  Perform the validation based on speed values at the transmission output shaft.  For steady-state tests (55 mph and 65 mph cruise), apply cycle-validation criteria by treating the sampling periods from the two tests as a continuous sampling period.  Perform this validation based on the following parameters:

    Table 1 of § 1037.550  -  Statistical criteria for validating duty cycles
                                    Parameter
                                  Speed Control
   Slope, a1
                             0.950 < a1 < 1.030
   Absolute value of intercept, |a0|
                         < 2.0 % of maximum test speed
   Standard error of estimate, SEE
                          < 5 % of maximum test speed
   Coefficient of determination, r[2]
                                    > 0.970

(f) Send a brake signal when throttle position is equal to zero and vehicle speed is greater than the reference vehicle speed from the test cycle.  Set a delay before changing the brake state to prevent the brake signal from dithering, consistent with good engineering judgment.
(g) The driver model should be designed to follow the cycle as closely as possible and must meet the requirements of § 1037.510 for steady-state testing and 40 CFR 1066.430(e) for transient testing.  The driver model should be designed so that the brake and throttle are not applied at the same time.
(h) Correct for the net energy change of the energy storage device as described in 40 CFR 1066.501.
(i) Follow the provisions of §1037.510 to weight the cycle results and §1037.615 to calculate improvement factors and benefits for advanced technologies for Phase 1 vehicles.

Subpart G -- Special Compliance Provisions
§ 1037.601  What compliance provisions apply?
(a) Engine and vehicle manufacturers, as well as owners and operators of vehicles subject to the requirements of this part, and all other persons, must observe the provisions of this part, the provisions of 40 CFR part 1068, and the provisions of the Clean Air Act.  The provisions of 40 CFR part 1068 apply for heavy-duty vehicles as specified in that part, subject to the following provisions:
   (1) Except as specifically allowed by this part, it is a violation of § 1068.101(a)(1) to introduce into U.S. commerce a tractor or vocational vehicle containing an engine not certified to the requirements of this part and 40 CFR part 86 corresponding to the calendar year for date of manufacture of the tractor or vocational vehicle.  Similarly, it is a violation to introduce into U.S. commerce a Phase 1 tractor containing an engine not certified for use in tractors; or to introduce into U.S. commerce a vocational vehicle containing a light heavy-duty or medium heavy-duty engine not certified for use in vocational vehicles.  These prohibitions apply especially to the vehicle manufacturer.  Note that this paragraph (a)(1) allows the use of Class 8 tractor engines in vocational vehicles.
   (2) The provisions of 40 CFR 1068.105(a) apply for vehicle manufacturers installing engines certified under 40 CFR part 1036 as further limited by this paragraph (a)(2).  If new engine emission standards apply in a given model year, you may install engines built before the date of the new or changed standards under the provisions of 40 CFR 1068.105(a) through March 31 of that year without our approval; you may not install such engines after March 31 of that year unless we approve it in advance.  In a written request for our approval, you must describe how your circumstances led you and your engine supplier to have normal inventories of engines that were not used up in the specified time frame. We will approve your request for up to three additional months to install up to 50 engines under this paragraph (a)(2) if we determine that the excess inventory is a result of unforeseeable circumstances and should not be considered circumvention of emission standards.
   (3)  The provisions of 40 CFR 1068.235 that allow for modifying certified vehicles and engines for competition do not apply for heavy-duty vehicles or heavy-duty engines.  Certified motor vehicles and motor vehicle engines and their emission control devices must remain in their certified configuration even if they are used solely for competition or if they become nonroad vehicles or engines; anyone modifying a certified motor vehicle or motor vehicle engine for any reason is subject to the tampering and defeat device prohibitions of 40 CFR 1068.101(b) and 42 U.S.C. 7522(a)(3).  Note that a new vehicle that will be used solely for competition may be excluded from the requirements of this part based on a determination that the vehicle is not a motor vehicle under 40 CFR 85.1703.
   (5) The tampering prohibition in 40 CFR 1068.101(b)(1) applies for alternative fuel conversions as specified in 40 CFR part 85, subpart F.
   (6) The warranty-related prohibitions in section 203(a)(4) of the Act (42 U.S.C. 7522(a)(4)) apply to manufacturers of new heavy-duty highway vehicles in addition to the prohibitions described in 40 CFR 1068.101(b)(6).  We may assess a civil penalty up to $37,500 for each engine or vehicle in violation.
   (7) The hardship exemption provisions of 40 CFR 1068.245, 1068.250, and 1068.255 do not apply for heavy-duty vehicles.
   (7) A vehicle manufacturer that completes assembly of a vehicle at two or more facilities may ask to use as the date of manufacture for that vehicle the date on which manufacturing is completed at the place of main assembly, consistent with provisions of 49 CFR 567.4.  Note that such staged assembly is subject to the provisions of 40 CFR 1068.260(c).  Include your request in your application for certification, along with a summary of your staged-assembly process.  You may ask to apply this allowance to some or all of the vehicles in your vehicle family.  Our approval is effective when we grant your certificate.  We will not approve your request if we determine that you intend to use this allowance to circumvent the intent of this part.
   (8) The provisions for selective enforcement audits apply as described in 40 CFR part 1068, subpart E, and §1037.301.
(b) Vehicles exempted from the applicable standards of 40 CFR part 86 are exempt from the standards of this part without request.  Similarly, vehicles are exempt without request if the installed engine is exempted from the applicable standards in 40 CFR part 86.
(c) The prohibitions of 40 CFR 86.1854 apply for vehicles subject to the requirements of this part.  The actions prohibited under this provision include the introduction into U.S. commerce of a complete or incomplete vehicle subject to the standards of this part where the vehicle is not covered by a valid certificate of conformity or exemption.
(d) The provisions of 40 CFR 85.1716 allow for approval of emergency vehicle field modifications.
(e) Under §1037.801, certain vehicles are considered to be new vehicles when they are imported into the United States, even if they have previously been used outside the country. Independent Commercial Importers may use the provisions of 40 CFR part 85, subpart P, and 40 CFR 85.1706(b) to receive a certificate of conformity for engines and vehicles meeting all the requirements of 40 CFR part 1036 and this part 1037.
(f) Standards apply to multi-fuel engines and vehicles as described in 40 CFR 1036.601(d).
(g) All electric vehicles are deemed to have zero emissions of CO2, CH4, and N2O.  No emission testing is required for electric vehicles.  Use good engineering judgment to apply other requirements of this part to electric vehicles.

§1037.605  Installing engines certified to alternate standards for specialty vehicles.
(a) General provisions. This section allows vehicle manufacturers to introduce into U.S. commerce certain new motor vehicles if the engines are certified to alternate emission standards that are
equivalent to standards that apply for nonroad engines under 40 CFR part 1039 or 1048.  See 40 CFR 86.007-11(g) and 40 CFR 86.008-10(g).  The provisions of this section apply for the following types of vehicles:
   (1) Vehicles with a hybrid powertrain in which the engine provides energy for the Rechargeable Energy Storage System.
   (2) Amphibious vehicles.
   (3) Vehicles with maximum speed at or below 45 miles per hour.  If your vehicle is speed-limited to meet this specification by reducing maximum speed below what is otherwise possible, this speed limitation must be programmed into the engine or vehicle's electronic control module in a way that is tamper-proof. If your vehicles are not inherently limited to a maximum speed at or below 45 miles per hour, they may qualify under this paragraph (a)(3) only if we approve your design to limit maximum speed as being tamper-proof in advance.
(b) Notification and reporting requirements. Send the Designated Compliance Officer written notification describing your plans before using the provisions of this section.  In addition, by February 28 of each calendar year (or less often if we tell you), send the Designated Compliance Officer a report with all the following information:
    (1) Identify your full corporate name, address, and telephone number.
    (2) List the vehicle and engine models for which you used this exemption in the previous year and identify the total number of vehicles.
(c) Production limits. . You may produce up to 1,000 hybrid vehicles, up to 200 amphibious vehicles, and up to 200 speed-limited vehicles under this section in a given model year.  This includes vehicles produced by affiliated companies.  If you exceed this limit, the exemption is void for the number of vehicles that exceed the limit for the model year.  For the purpose of this paragraph (c), we will include all vehicles labeled or otherwise identified as exempt under this section.
(d) Vehicle standards. Vehicles using the provisions of this section remain subject to all other requirements of this part 1037.  For example, you must use GEM to demonstrate compliance with emission standards under subpart B of this part.

§ 1037.610  Vehicles with off-cycle technologies.
(a) You may ask us to apply the provisions of this section for CO2 emission reductions resulting from vehicle technologies that were not in common use with heavy-duty vehicles before model year 2010 that are not reflected in the GEM simulation tool.  These may be described as off-cycle or innovative technologies.  These provisions may be applied for CO2 emission reductions reflected using the specified test procedures, provided they are not reflected in the GEM.  We will apply these provisions only for technologies that will result in measurable, demonstrable, and verifiable real-world CO2 emission reductions.
(b) The provisions of this section may be applied as either an improvement factor or as a separate credit within the vehicle family, consistent with good engineering judgment.  We recommend that you base your credit/adjustment on A to B testing of pairs of vehicles differing only with respect to the technology in question.
   (1) Calculate improvement factors as the ratio of in-use emissions with the technology divided by the in-use emissions without the technology.  Use the improvement-factor approach where good engineering judgment indicates that the actual benefit will be proportional to emissions measured over the test procedures specified in this part.
   (2) Calculate separate credits (g/ton-mile) based on the difference between the in-use emission rate with the technology and the in-use emission rate without the technology.  Subtract this value from your GEM result and use this adjusted value to determine your FEL.  Use the separate-credit approach where good engineering judgment indicates that the actual benefit will be not be proportional to emissions measured over the test procedures specified in this part.
   (3) We may require you to discount or otherwise adjust your improvement factor or credit to account for uncertainty or other relevant factors.
(c) You may perform A to B testing by measuring emissions from the vehicles during chassis testing or from in-use on-road testing.  We recommend that you perform on-road testing according to SAE J1321 Joint TMC/SAE Fuel Consumption Test Procedure Type II Reaffirmed 1986-10 or SAE J1526 Joint TMC/SAE Fuel Consumption In-Service Test Procedure Type III Issued 1987-06 (see §1037.810 for information on availability of SAE standards), subject to the following provisions:
   (1) The minimum route distance is 100 miles.
   (2) The route selected must be representative in terms of grade.  We will take into account published and relevant research in determining whether the grade is representative.
   (3) The vehicle speed over the route must be representative of the drive-cycle weighting adopted for each regulatory subcategory.  For example, if the route selected for an evaluation of a combination tractor with a sleeper cab contains only interstate driving, the improvement factor would apply only to 86 percent of the weighted result.
   (4) The ambient air temperature must be between (5 and 35) °C, unless the technology requires other temperatures for demonstration.
   (5) We may allow you to use a Portable Emissions Measurement System (PEMS) device for measuring CO2 emissions during the on-road testing.
(d) Send your request to the Designated Compliance Officer.  We recommend that you do not begin collecting test data (for submission to EPA) before contacting us.  For technologies for which the engine manufacturer could also claim credits (such as transmissions in certain circumstances), we may require you to include a letter from the engine manufacturer stating that it will not seek credits for the same technology.  Your request must contain the following items:
   (1) A detailed description of the off-cycle technology and how it functions to reduce CO2 emissions under conditions not represented on the duty cycles required for certification.
   (2) A list of the vehicle configurations that will be equipped with the technology.
   (3) A detailed description and justification of the selected test vehicles.
   (4) All testing and simulation data required under this section, plus any other data you have considered in your analysis.  You may ask for our preliminary approval of your test plan under §1037.210.
   (5) A complete description of the methodology used to estimate the off-cycle benefit of the technology and all supporting data, including vehicle testing and in-use activity data.  Also include a statement regarding your recommendation for applying the provisions of this section for the given technology as an improvement factor or a credit.
   (6) An estimate of the off-cycle benefit by vehicle model, and the fleetwide benefit based on projected sales of vehicle models equipped with the technology.
   (7) A demonstration of the in-use durability of the off-cycle technology, based on any available engineering analysis or durability testing data (either by testing components or whole vehicles).
(e) We may seek public comment on your request, consistent with the provisions of 40 CFR 86.1866.  However, we will generally not seek public comment on credits or adjustments based on A to B chassis testing performed according to the duty-cycle testing requirements of this part or in-use testing performed according to paragraph (c) of this section.
(f) We may approve an improvement factor or credit for any vehicle family that is properly represented by your testing.  You may similarly continue to use an approved improvement factor or credit for any appropriate vehicle families in future model years through 2020.  Starting in model year 2021, you must request our approval before applying an improvement factor or credit under this section for any kind of technology, even if we approved an improvement factor or credit for similar vehicle models before model year 2021.

§ 1037.615  Hybrid vehicles and other advanced technologies.
(a) This section applies to Phase 1 for hybrid vehicles with regenerative braking, vehicles equipped with Rankine-cycle engines, electric vehicles, and fuel cell vehicles.  You may not generate credits for engine features for which the engines generate credits under 40 CFR part 1036.
(b) Generate advanced technology emission credits for hybrid vehicles that include regenerative braking (or the equivalent) and energy storage systems, fuel cell vehicles, and vehicles equipped with Rankine-cycle engines as follows:
   (1) Measure the effectiveness of the advanced system by chassis testing a vehicle equipped with the advanced system and an equivalent conventional vehicle, or by testing the hybrid systems and the equivalent non-hybrid systems as described in § 1037.550. Test the vehicles as specified in subpart F of this part. For purposes of this paragraph (b), a conventional vehicle is considered to be equivalent if it has the same footprint (as defined in 40 CFR 86.1803), vehicle service class, aerodynamic drag, and other relevant factors not directly related to the hybrid powertrain. If you use § 1037.540 to quantify the benefits of a hybrid system for PTO operation, the conventional vehicle must have the same number of PTO circuits and have equivalent PTO power. If you do not produce an equivalent vehicle, you may create and test a prototype equivalent vehicle. The conventional vehicle is considered Vehicle A and the advanced vehicle is considered Vehicle B. We may specify an alternate cycle if your vehicle includes a power take-off.
    (2) Calculate an improvement factor and g/ton-mile benefit using the following equations and parameters:
      (i) Improvement Factor = [(Emission Rate A)  -  (Emission Rate B)]/(Emission Rate A)
      (ii) g/ton-mile benefit = Improvement Factor x (GEM Result B)
      (iii) Emission Rates A and B are the g/ton-mile CO2 emission rates of the conventional and advanced vehicles, respectively, as measured under the test procedures specified in this section.  GEM Result B is the g/ton-mile CO2 emission rate resulting from emission modeling of the advanced vehicle as specified in §1037.520.
   (3) If you apply an improvement factor to multiple vehicle configurations using the same advanced technology, use the vehicle configuration with the smallest potential reduction in greenhouse gas emissions resulting from the hybrid capability.
   (4) Use the equations of §1037.705 to convert the g/ton-mile benefit to emission credits (in Mg).  Use the g/ton-mile benefit in place of the (Std-FEL) term.
(c) See §1037.540 for special testing provisions related to vehicles equipped with hybrid power take-off units.
(d) You may use an engineering analysis to calculate an improvement factor for fuel cell vehicles based on measured emissions from the fuel cell vehicle.
(e) For electric vehicles, calculate CO2 credits using an FEL of 0 g/ton-mile.
(f) As specified in subpart H of this part, credits generated under this section may be used under this part 1037 outside of the averaging set in which they were generated or used under 40 CFR part 1036.
(g) You may certify using both provisions of this section and the off-cycle technology provisions of §1037.610, provided you do not double count emission benefits.

§ 1037.620  Responsibilities for multiple manufacturers.
This section describes certain circumstances in which multiple manufacturers share responsibilities for vehicle they produce together.  This section does limit responsibilities that apply under the Act or these regulations for anyone meeting the definition of "manufacturer" in §1037.801.
(a) The delegated assembly provisions of §1037.621 apply for certifying manufacturers that rely on other manufacturers to finish assembly in a certified configuration.  The provisions of §1037.622 apply for manufacturers that ship vehicles subject to the requirements of this section to a certifying secondary vehicle manufacturer.  The provisions of §1037.622 also apply to the secondary manufacturer.
(b) Manufacturers of aerodynamic devices may perform the aerodynamic testing described in §1037.525 to quantify CDA values for trailers and submit that data to EPA verification under §1037.211.  Trailer manufacturers may use such verified data to establish GEM inputs for certifying their trailers.  Both device manufacturers and trailer manufacturers are subject to the recall provisions described in 40 CFR part 1068, subpart F.

§ 1037.621  Delegated assembly.
(a) This section describes an exemption that allows certificate holders to sell or ship vehicles that are missing certain emission-related components if those components will be installed by a secondary vehicle manufacturer.  (Note: See §1037.622 for provisions related to manufacturers introducing into U.S. commerce partially complete vehicles for which a secondary vehicle manufacturer holds the certificate of conformity.)  This exemption is temporary as described in paragraph (f) of this section.
(b) The provisions of 40 CFR 1068.261 apply for vehicles subject to GHG standards under this part, with the following exceptions and clarifications:
   (1) Understand references to "engines" to refer to vehicles.
   (2) Understand references to "aftertreatment components" to refer to any emission-related components needed for complying with GHG standards under this part.
   (3) Understand "equipment manufacturers" to be secondary vehicle manufacturers.
   (4) The provisions of 40 CFR 1068.261(b), (c)(7), (d), and (e) do not apply. Accordingly, the provisions of 40 CFR 1068.261(c) apply regardless of pricing arrangements.

§ 1037.622  Shipment of incomplete vehicles to secondary vehicle manufacturers.
This section specifies how manufacturers may introduce partially complete vehicles into U.S. commerce.  The provisions of this section do not apply for trailers, except in unusual circumstances.  You may not use the provisions of this section to circumvent the intent of this part.
(a) The provisions of this section allow manufacturers to ship partially complete vehicles to secondary vehicle manufacturers or otherwise introduce them into U.S. commerce in the following circumstances:
   (1) Tractors.  Manufacturers may introduce partially complete tractors into U.S. commerce if they are covered by a certificate of conformity for tractors and will be in their certified tractor configuration before they reach the ultimate purchasers.  For example, this would apply for sleepers initially shipped without the sleeper compartments attached.  Small businesses that build custom sleeper cabs may modify complete or incomplete vehicles certified as tractors under this section, as long as they do not increase the effective frontal area of the certified configuration.  Note that delegated assembly provisions may apply (see §1037.621).
   (2) Vocational vehicles. Manufacturers may introduce partially complete vocational vehicles into U.S. commerce if they are covered by a certificate of conformity for vocational vehicles and will be in their certified vocational configuration before they reach the ultimate purchasers.  Note that delegated assembly provisions may apply (see §1037.621).
   (3) Uncertified vehicles that will be certified by secondary vehicle manufacturers. Manufacturers may introduce into U.S. commerce partially complete vehicles for which they do not hold a certificate of conformity only as allowed by paragraph (b) of this section; however, the requirements of this section do not apply for tractors or vocational vehicles built before January 1, 2022, that are produced by a secondary vehicle manufacturer if they are excluded from the standards of this part under § 1037.150(c).
(b) The provisions of this paragraph (b) apply where the secondary vehicle manufacturer has substantial control over the design and assembly of emission controls.  In determining whether a manufacturer has substantial control over the design and assembly of emission controls, we would consider the degree to which the secondary manufacturer would be able to ensure that the engine and vehicle will conform to the regulations in their final configurations.
   (1) A secondary manufacturer may finish assembly of partially complete vehicles in the following cases:
      (i) It obtains a vehicle that is not fully assembled with the intent to manufacture a complete vehicle in a certified configuration.
      (ii) It obtains a vehicle with the intent to modify it to a certified configuration before it reaches the ultimate purchaser.  For example, this may apply for converting a gasoline-fueled vehicle to operate on natural gas under the terms of a valid certificate.
   (2) Manufacturers may introduce partially complete vehicles into U.S. commerce as described in this paragraph (b) if they have a written request for such vehicles from a secondary vehicle manufacturer that will finish the vehicle assembly and has certified the vehicle (or the vehicle has been exempted or excluded from the requirements of this part).  The written request must include a statement that the secondary manufacturer has a certificate of conformity (or exemption/exclusion) for the vehicle and identify a valid vehicle family name associated with each vehicle model ordered (or the basis for an exemption/exclusion). The original vehicle manufacturer must apply a removable label meeting the requirements of 40 CFR 1068.45 that identifies the corporate name of the original manufacturer and states that the vehicle is exempt under the provisions of §1037.622. The name of the certifying manufacturer must also be on the label or, alternatively, on the bill of lading that accompanies the vehicles during shipment. The original manufacturer may not apply a permanent emission control information label identifying the vehicle's eventual status as a certified vehicle.
   (3) If you are the secondary manufacturer and you will hold the certificate, you must include the following information in your application for certification:
      (i) Identify the original manufacturer of the partially complete vehicle or of the complete vehicle you will modify.
      (ii) Describe briefly how and where final assembly will be completed. Specify how you have the ability to ensure that the vehicles will conform to the regulations in their final configuration. (Note: This section prohibits using the provisions of this paragraph (b) unless you have substantial control over the design and assembly of emission controls.)
      (iii) State unconditionally that you will not distribute the vehicles without conforming to all applicable regulations.
   (4) If you are a secondary manufacturer and you are already a certificate holder for other families, you may receive shipment of partially complete vehicles after you apply for a certificate of conformity but before the certificate's effective date. This exemption allows the original manufacturer to ship vehicles after you have applied for a certificate of conformity. Manufacturers may introduce partially complete vehicles into U.S. commerce as described in this paragraph (b)(4) if they have a written request for such vehicles from a secondary manufacturer stating that the application for certification has been submitted (instead of the information we specify in paragraph (b)(2) of this section). We may set additional conditions under this paragraph (b)(4) to prevent circumvention of regulatory requirements.
   (5) The provisions of this section also apply for shipping partially complete vehicles if the vehicle is covered by a valid exemption and there is no valid family name that could be used to represent the vehicle model. Unless we approve otherwise in advance, you may do this only when shipping engines to secondary manufacturers that are certificate holders. In this case, the secondary manufacturer must identify the regulatory cite identifying the applicable exemption instead of a valid family name when ordering engines from the original vehicle manufacturer.
   (6) Both original and secondary manufacturers must keep the records described in this section for at least five years, including the written request for exempted vehicles and the bill of lading for each shipment (if applicable). The written request is deemed to be a submission to EPA.
   (7) These provisions are intended only to allow secondary manufacturers to obtain or transport vehicles in the specific circumstances identified in this section so any exemption under this section expires when the vehicle reaches the point of final assembly identified in paragraph (b)(3)(ii) of this section.
   (8) For purposes of this section, an allowance to introduce partially complete vehicles into U.S. commerce includes a conditional allowance to sell, introduce, or deliver such vehicles into commerce in the United States or import them into the United States. It does not include a general allowance to offer such vehicles for sale because this exemption is intended to apply only for cases in which the certificate holder already has an arrangement to purchase the vehicles from the original manufacturer. This exemption does not allow the original manufacturer to subsequently offer the vehicles for sale to a different manufacturer who will hold the certificate unless that second manufacturer has also complied with the requirements of this part. The exemption does not apply for any individual vehicles that are not labeled as specified in this section or which are shipped to someone who is not a certificate holder.
   (9) We may suspend, revoke, or void an exemption under this section, as follows:
      (i) We may suspend or revoke your exemption if you fail to meet the requirements of this section. We may suspend or revoke an exemption related to a specific secondary manufacturer if that manufacturer sells vehicles that are in not in a certified configuration in violation of the regulations. We may disallow this exemption for future shipments to the affected secondary manufacturer or set additional conditions to ensure that vehicles will be assembled in the certified configuration.
      (ii) We may void an exemption for all the affected vehicles if you intentionally submit false or incomplete information or fail to keep and provide to EPA the records required by this section.
      (iii) The exemption is void for a vehicle that is shipped to a company that is not a certificate holder or for a vehicle that is shipped to a secondary manufacturer that is not in compliance with the requirements of this section.
      (iv) The secondary manufacturer may be liable for penalties for causing a prohibited act where the exemption is voided due to actions on the part of the secondary manufacturer.
(c) Provide instructions along with partially complete vehicles including all information necessary to ensure that an engine will be installed in its certified configuration.

§ 1037.630  Special purpose tractors.
(a) General provisions.  This section allows a vehicle manufacturer to reclassify certain tractors as vocational tractors.  Vocational tractors are treated as vocational vehicles and are exempt from the standards of §1037.106.  Note that references to "tractors" outside of this section mean non-vocational tractors.
   (1)  This allowance is intended only for vehicles that do not typically operate at highway speeds, or would otherwise not benefit from efficiency improvements designed for line-haul tractors.  This allowance is limited to the following vehicle and application types:
      (i)  Low-roof tractors intended for intra-city pickup and delivery, such as those that deliver bottled beverages to retail stores.
      (ii) Tractors intended for off-road operation (including mixed service operation), such as those with reinforced frames and increased ground clearance.
      (iii) Tractors with a GCWR over 120,000 pounds (through model year 2020 only).
   (2) Where we determine that a manufacturer is not applying this allowance in good faith, we may require the manufacturer to obtain preliminary approval before using this allowance.
(b)  Requirements.  The following requirements apply with respect to tractors reclassified under this section:
   (1) The vehicle must fully conform to all requirements applicable to vocational vehicles under this part.
   (2) Vehicles reclassified under this section must be certified as a separate vehicle family.  However, they remain part of the vocational regulatory subcategory and averaging set that applies for their weight class.
   (3) You must include the following additional statement on the vehicle's emission control information label under §1037.135: "THIS VEHICLE WAS CERTIFIED AS A VOCATIONAL TRACTOR UNDER 40 CFR 1037.630."
   (4) You must keep records for three years to document your basis for believing the vehicles will be used as described in paragraph (a)(1) of this section.  Include in your application for certification a brief description of your basis.
(c) Production limit.  No manufacturer may produce more than 21,000 vehicles under this section in any consecutive three model year period.  This means you may not exceed 6,000 in a given model year if the combined total for the previous two years was 15,000.  The production limit applies with respect to all Class 7 and Class 8 tractors certified or exempted as vocational tractors.  Note that in most cases, the provisions of paragraph (a) of this section will limit the allowable number of vehicles to be a number lower than the production limit of this paragraph (c).
(d) Off-road exemption.  All the provisions of this section apply for vocational tractors exempted under §1037.631, except as follows:
   (1) The vehicles are required to comply with the requirements of §1037.631 instead of the requirements that would otherwise apply to vocational vehicles.  Vehicles complying with the requirements of §1037.631 and using an engine certified to the standards of 40 CFR part 1036 are deemed to fully conform to all requirements applicable to vocational vehicles under this part.
   (2) The vehicles must be labeled as specified under §1037.631 instead of as specified in paragraph (b)(3) of this section.

§ 1037.631  Exemption for vocational vehicles intended for off-road use.
This section provides an exemption from the greenhouse gas standards of this part for certain vocational vehicles intended to be used extensively in off-road environments such as forests, oil fields, and construction sites.  This section does not exempt engines used in vocational vehicles from the standards of 40 CFR part 86 or part 1036.  Note that you may not include these exempted vehicles in any credit calculations under this part.  Note also that trailers intended for off-road use are generally excluded from the requirements of this part under §1037.5.
(a) Qualifying criteria. Vocational vehicles intended for off-road use are exempt without request, subject to the provisions of this section, if they are primarily designed to perform work off-road (such as in oil fields, mining, forests, or construction sites), and they meet at least one of the criteria of paragraph (a)(1) of this section and at least one of the criteria of paragraph (a)(2) of this section.
    (1) The vehicle must have affixed components designed to work in an off-road environment (i.e., hazardous material equipment or off-road drill equipment) or be designed to operate at low speeds such that it is unsuitable for normal highway operation.
    (2) The vehicle must meet one of the following criteria:
       (i) Have an axle that has a gross axle weight rating (GAWR) at or above 29,000 pounds.
       (ii) Have a speed attainable in 2.0 miles of not more than 33 mph.
       (iii) Have a speed attainable in 2.0 miles of not more than 45 mph, an unloaded vehicle weight that is not less than 95 percent of its gross vehicle weight rating, and no capacity to carry occupants other than the driver and operating crew.
(b) Tractors. The provisions of this section may apply for tractors only if each tractor qualifies as a vocational tractor under §1037.630.