# 40 CFR § 600.116-12 - Special procedures related to electric vehicles and hybrid electric vehicles.

(a) Determine fuel economy values for electric vehicles as specified in §§ 600.210 and 600.311 using the procedures of SAE J1634 (incorporated by reference in § 600.011). Use the procedures of SAE J1634, Section 8, with the following clarifications and modifications for using this and other sections of SAE J1634:

(1) Vehicles that cannot complete the Multi-Cycle Range and Energy Consumption Test (MCT) because they are unable travel the distance required to complete the test with a fully charged battery, or they are unable to achieve the maximum speed on either the UDDS or HFEDS (Highway Fuel Economy Drive Cycle also known as the HFET) cycle should seek Administrator approval to use the procedures outlined in SAE J1634 Section 7 Single Cycle Range and Energy Consumption Test (SCT).

(2) The MCT includes the following key-on soak times and key-off soak periods:

(i) As noted in SAE J1634 Section 8.3.4, a 15 second key-on pause is required between UDDS1 and HFEDS1, and UDDS3 and HFEDS2.

(ii) As noted in SAE J1634 Section 8.3.4, a 10-minute key-off soak period is required between HFEDS1 and UDDS2, and HFEDS2 and UDDS4.

(iii) A key-off soak period up to 30 minutes may be inserted between UDDS2 and the first phase of the mid-test constant speed cycle, between UDDS4 and the first phase of the end-of-test constant speed cycle, and between the end of the mid-test constant speed cycle and UDDS3. Start the next test segment immediately if there is no key-off soak between test segments.

(iv) If multiple phases are required during either the mid-test constant speed cycle or the end-of-test constant speed cycle there must be a 5-minute to 30-minute key-off soak period between each constant speed phase as noted in SAE J1634 Section 6.6.

(3) As noted in SAE J1634 Section 8.3.4, during all `key-off' soak periods, the key or power switch must be in the “off” position, the hood must be closed, the test cell fan(s) must be off, and the brake pedal not depressed. For vehicles which do not have a key or power switch the vehicle must be placed in the `mode' the manufacturer recommends when the vehicle is to be parked and the occupants exit the vehicle.

(4) Manufacturers may determine the mid-test constant speed cycle distance (dM) using their own methodology and good engineering judgment. Otherwise, either Method 1 or Method 2 described in Appendix A of SAE J1634 may be used to estimate the mid-test constant speed cycle distance (dM). The mid-test constant speed cycle distance calculation needs to be performed prior to beginning the test and should not use data from the test being performed. If Method 2 is used, multiply the result determined by the Method 2 equation by 0.8 to determine the mid-test constant speed cycle distance (dM).

(5) Divide the mid-test constant speed cycle distance (dM) by 65 mph to determine the total time required for the mid-test constant speed cycle. If the time required is one hour or less, the mid-test constant speed cycle can be performed with no key-off soak periods. If the time required is greater than one hour, the mid-test constant speed cycle must be separated into phases such that no phase exceeds more than one hour. At the conclusion of each mid-test constant speed phase, except at the conclusion of the mid-test constant speed cycle, perform a 5-minute to 30-minute key-off soak. A key-off soak period up to 30 minutes may be inserted between the end of the mid-test constant speed cycle and UDDS3.

(6) Using good engineering judgment determine the end-of-test constant speed cycle distance so that it does not exceed 20% of the total distance driven during the MCT as described in SAE J1634 Section 8.3.3.

(7) Divide the end-of-test constant speed cycle distance (dE) by 65 mph to determine the total time required for the end-of-test constant speed cycle. If the time required is one-hour or less the end-of-test constant speed cycle can be performed with no key-off soak periods. If the time required is greater than one-hour the end-of-test constant speed cycle must be separated into phases such that no phase exceeds more than one-hour. At the conclusion of each end-of-test constant speed phase, perform a 5-minute to 30-minute key-off soak.

(8) SAE J1634 Section 3.13 defines useable battery energy (UBE) as the total DC discharge energy (Edctotal), measured in DC watt-hours for a full discharge test. The total DC discharge energy is the sum of all measured phases of a test inclusive of all drive cycle types. As key-off soak periods are not considered part of the test phase, the discharge energy that occurs during the key-off soak periods is not included in the useable battery energy.

(9) Recharging the vehicle's battery must start within three hours after the end of testing.

(10) At the request of a manufacturer, the Administrator may approve the use of an earlier version of SAE J1634 when a manufacturer is carrying over data for vehicles tested using a prior version of SAE J1634.

(11) All label values related to fuel economy, energy consumption, and range must be based on 5-cycle testing or on values adjusted to be equivalent to 5-cycle results. Prior to performing testing to generate a 5-cycle adjustment factor, manufacturers must request Administrator approval to use SAE J1634 Appendices B and C for determining a 5-cycle adjustment factor with the following modifications, clarifications, and attestations:

(i) Before model year 2025, prior to performing the 20 °F charge-depleting UDDS, the vehicle must soak for a minimum of 12 hours and a maximum of 36 hours at a temperature of 20 °F. Prior to beginning the 12 to 36 hour cold soak at 20 °F the vehicle must be fully charged, the charging can take place at test laboratory ambient temperatures (68 to 86 °F) or at 20 °F. During the 12 to 36 hour cold soak period the vehicle may not be connected to a charger nor is the vehicle cabin or battery to be preconditioned during the 20 °F soak period.

(ii) Beginning with model year 2025, the 20 °F UDDS charge-depleting UDDS test will be replaced with a 20 °F UDDS test consisting of two UDDS cycles performed with a 10-minute key-off soak between the two UDDS cycles. The data from the two UDDS cycles will be used to calculate the five-cycle adjustment factor, instead of using the results from the entire charge-depleting data set. Manufacturers that have submitted and used the average data from 20 °F charge-depleting UDDS data sets will be required to revise their 5-cycle adjustment factor calculation and re-label vehicles using the data from the first two UDDS cycles only. Manufacturers, at their discretion, would also be allowed to re-run the 20 °F UDDS test with the battery charged to a state-of-charge (SoC) determined by the manufacturer. The battery does not need to be at 100% SoC before the 20 °F cold soak.

(iii) Manufacturers must submit a written attestation to the Administrator at the completion of testing with the following information:

(A) A statement noting the SoC level of the rechargeable energy storage system (RESS) prior to beginning the 20 °F cold soak for testing performed beginning with model year 2025.

(B) A statement confirming the vehicle was not charged or preconditioned during the 12 to 36 hour 20 °F soak period before starting the 20 °F UDDS cycle.

(C) A summary of all the 5-cycle test results and the calculations used to generate the 5-cycle adjustment factor, including all the 20 °F UDDS cycles, the distance travelled during each UDDS and the measured DC discharge energy during each UDDS phase. Beginning in model year 2025, the 20 °F UDDS test results will consist of only two UDDS cycles.

(D) Beginning in model year 2025, calculate City Fuel Economy using the following equation for RunningFC instead of the equation on Page 30 in Appendix C of SAE J1634:

(E) A description of each test group and configuration which will use the 5-cycle adjustment factor, including the battery capacity of the vehicle used to generate the 5-cycle adjustment factor and the battery capacity of all the configurations to which it will be applied.

(iv) At the conclusion of the manufacturers testing and after receiving the attestations from the manufacturer regarding the performance of the 20 °F UDDS test processes, the 5-cycle test results, and the summary of vehicles to which the manufacturer proposes applying the 5-cycle adjustment factor, the Administrator will review the submittals and inform the manufacturer in writing if the Administrator concurs with the manufacturer's proposal. If not, the Administrator will describe the rationale to the manufacturer for not approving their request.

(b) Determine performance values for hybrid electric vehicles that have no plug-in capability as specified in §§ 600.210 and 600.311 using the procedures for charge-sustaining operation from SAE J1711 (incorporated by reference in § 600.011). We may approve alternate measurement procedures with respect to these vehicles if that is necessary or appropriate for meeting the objectives of this part. For example, we may approve alternate Net Energy Change tolerances for charge-sustaining operation as described in paragraph (c)(5) of this section.

(c) Determine performance values for hybrid electric vehicles that have plug-in capability as specified in §§ 600.210 and 600.311 using the procedures of SAE J1711 (incorporated by reference in § 600.011), with the following clarifications and modifications:

(1) To determine CREE values to demonstrate compliance with GHG standards, calculate composite values representing combined operation during charge-depleting and charge-sustaining operation using the following utility factors except as specified in this paragraph (c):

Table 1 of § 600.116-12—Fleet Utility Factors for Urban “City” Driving

Schedule range for UDDS phases, miles | Cumulative
UF |
Sequential
UF |
---|---|---|

3.59 | 0.125 | 0.125 |

7.45 | 0.243 | 0.117 |

11.04 | 0.338 | 0.095 |

14.90 | 0.426 | 0.088 |

18.49 | 0.497 | 0.071 |

22.35 | 0.563 | 0.066 |

25.94 | 0.616 | 0.053 |

29.80 | 0.666 | 0.049 |

33.39 | 0.705 | 0.040 |

37.25 | 0.742 | 0.037 |

40.84 | 0.772 | 0.030 |

44.70 | 0.800 | 0.028 |

48.29 | 0.822 | 0.022 |

52.15 | 0.843 | 0.021 |

55.74 | 0.859 | 0.017 |

59.60 | 0.875 | 0.016 |

63.19 | 0.888 | 0.013 |

67.05 | 0.900 | 0.012 |

70.64 | 0.909 | 0.010 |

Table 2 of § 600.116-12—Fleet Utility Factors for Highway Driving

Schedule range for HFET, miles | Cumulative
UF |
Sequential
UF |
---|---|---|

10.3 | 0.123 | 0.123 |

20.6 | 0.240 | 0.117 |

30.9 | 0.345 | 0.105 |

41.2 | 0.437 | 0.092 |

51.5 | 0.516 | 0.079 |

61.8 | 0.583 | 0.067 |

72.1 | 0.639 | 0.056 |

(2) Determine fuel economy values to demonstrate compliance with CAFE standards as follows:

(i) For vehicles that are not dual fueled automobiles, determine fuel economy using the utility factors described in paragraph (c)(1) of this section. Do not use the petroleum-equivalence factors described in 10 CFR 474.3.

(ii) Except as described in paragraph (c)(2)(iii) of this section, determine fuel economy for dual fueled automobiles from the following equation, separately for city and highway driving:

(iii) For 2016 and later model year dual fueled automobiles, you may determine fuel economy based on the following equation, separately for city and highway driving:

(3) To determine fuel economy and CO2 emission values for labeling purposes, calculate composite values representing combined operation during charge-depleting and charge-sustaining operation using the following utility factors except as specified in this paragraph (c):

Table 3 of § 600.116-12—Multi-Day Individual Utility Factors for Urban “City” Driving

Schedule range for UDDS phases, miles | Equivalent 5-cycle distance, miles | Cumulative
UF |
Sequential
UF |
---|---|---|---|

3.59 | 2.51 | 0.08 | 0.08 |

7.45 | 5.22 | 0.15 | 0.08 |

11.04 | 7.73 | 0.22 | 0.06 |

14.90 | 10.43 | 0.28 | 0.06 |

18.49 | 12.94 | 0.33 | 0.05 |

22.35 | 15.65 | 0.38 | 0.05 |

25.94 | 18.16 | 0.43 | 0.04 |

29.80 | 20.86 | 0.47 | 0.04 |

33.39 | 23.37 | 0.50 | 0.04 |

37.25 | 26.08 | 0.54 | 0.04 |

40.84 | 28.59 | 0.57 | 0.03 |

44.70 | 31.29 | 0.60 | 0.03 |

48.29 | 33.80 | 0.62 | 0.02 |

52.15 | 36.51 | 0.65 | 0.02 |

55.74 | 39.02 | 0.67 | 0.02 |

59.60 | 41.72 | 0.69 | 0.02 |

63.19 | 44.23 | 0.71 | 0.02 |

67.05 | 46.94 | 0.72 | 0.02 |

70.64 | 49.45 | 0.74 | 0.01 |

74.50 | 52.15 | 0.75 | 0.01 |

78.09 | 54.66 | 0.78 | 0.03 |

81.95 | 57.37 | 0.79 | 0.01 |

85.54 | 59.88 | 0.80 | 0.01 |

89.40 | 62.58 | 0.81 | 0.01 |

92.99 | 65.09 | 0.82 | 0.01 |

Table 4 of § 600.116-12—Multi-Day Individual Utility Factors for Highway Driving

Schedule range for HFET phases, miles | Equivalent 5-cycle distance, miles | Cumulative
UF |
Sequential
UF |
---|---|---|---|

10.30 | 7.21 | 0.21 | 0.21 |

20.60 | 14.42 | 0.36 | 0.16 |

30.90 | 21.63 | 0.48 | 0.12 |

41.20 | 28.84 | 0.57 | 0.09 |

51.50 | 36.05 | 0.64 | 0.07 |

61.80 | 43.26 | 0.70 | 0.06 |

72.10 | 50.47 | 0.75 | 0.04 |

82.40 | 57.68 | 0.78 | 0.04 |

92.70 | 64.89 | 0.81 | 0.03 |

103.00 | 72.10 | 0.83 | 0.02 |

113.30 | 79.31 | 0.85 | 0.02 |

(4) You may calculate performance values under paragraphs (c)(1) through (3) of this section by combining phases during FTP testing. For example, you may treat the first 7.45 miles as a single phase by adding the individual utility factors for that portion of driving and assigning emission levels to the combined phase. Do this consistently throughout a test run.

(5) Instead of the utility factors specified in paragraphs (c)(1) through (3) of this section, calculate utility factors using the following equation for vehicles whose maximum speed is less than the maximum speed specified in the driving schedule, where the vehicle's maximum speed is determined, to the nearest 0.1 mph, from observing the highest speed over the first duty cycle (FTP, HFET, etc.):

Table 5 of § 600.116-12—City/Highway Specific Utility Factor Coefficients

Coefficient | Fleet values for CAFE and GHG values | Multi-day individual value for labeling | |
---|---|---|---|

City | Highway | City or highway | |

1 | 14.86 | 4.8 | 13.1 |

2 | 2.965 | 13 | −18.7 |

3 | −84.05 | −65 | 5.22 |

4 | 153.7 | 120 | 8.15 |

5 | −43.59 | −100.00 | 3.53 |

6 | −96.94 | 31.00 | −1.34 |

7 | 14.47 | −4.01 | |

8 | 91.70 | −3.90 | |

9 | −46.36 | −1.15 | |

10 | 3.88 |

(6) The End-of-Test criterion is based on a 1 percent Net Energy Change as specified in Section 3.8 of SAE J1711. We may approve alternate Net Energy Change tolerances as specified in Section 3.9.1 of SAE J1711 for charge-depleting tests or Appendix C of SAE J1711 for charge-sustaining tests if the 1 percent threshold is insufficient or inappropriate. For charge-sustaining tests, we may approve the use of alternate Net Energy Change tolerances as specified in Appendix C of SAE J1711 to correct final fuel economy values, CO2 emissions, and carbon-related exhaust emissions. For charge-sustaining tests, do not use alternate Net Energy Change tolerances to correct emissions of criteria pollutants. Additionally, if we approve an alternate End-of-Test criterion or Net Energy Change tolerances for a specific vehicle, we may use the alternate criterion or tolerances for any testing we conduct on that vehicle.

(7) Use the vehicle's Actual Charge-Depleting Range, Rcda, as specified in Section 6.1.3 for evaluating the end-of-test criterion.

(8) Measure and record AC watt-hours throughout the recharging procedure. Position the measurement appropriately to account for any losses in the charging system.

(9) We may approve alternate measurement procedures with respect to plug-in hybrid electric vehicles if they are necessary or appropriate for meeting the objectives of this part.

(10) The utility factors described in this paragraph (c) are derived from equations in SAE J2841. You may alternatively calculate utility factors directly from the corresponding equations in SAE J2841.

(d) Determining the proportion of recovered energy for hybrid electric vehicles. Testing of hybrid electric vehicles under this part may include a determination of the proportion of energy recovered over the FTP relative to the total available braking energy required over the FTP. This determination is required for pickup trucks accruing credits for implementation of hybrid technology under § 86.1870-12, and requires the measurement of electrical current (in amps) flowing into the hybrid system battery for the duration of the test. Hybrid electric vehicles are tested for fuel economy and GHG emissions using the 4-bag FTP as required by § 600.114(c). Alternative measurement and calculation methods may be used with prior EPA approval.

(1) Calculate the theoretical maximum amount of energy that could be recovered by a hybrid electric vehicle over the FTP test cycle, where the test cycle time and velocity points are expressed at 10 Hz, and the velocity (miles/hour) is expressed to the nearest 0.01 miles/hour, as follows:

(i) For each time point in the 10 Hz test cycle (i.e., at each 0.1 seconds):

(A) Determine the road load power in kilowatts using the following equation:

(B) Determine the applied deceleration power at each sampling point in time, t, in kilowatts, using the following equation. Positive values indicate acceleration and negative values indicate deceleration.

(C) Determine braking power in kilowatts using the following equation. Note that during braking events, Pbrake, Paccel, and Proadload will all be negative (i.e., resistive) forces on the vehicle.

(ii) The total maximum braking energy (Ebrake) that could theoretically be recovered is equal to the absolute value of the sum of all the values of Pbrake determined in paragraph (d)(1)(i)(C) of this section, divided by 36000 (to convert 10 Hz data to hours) and rounded to the nearest 0.01 kilowatt-hours.

(ii) The total maximum braking energy (Ebrake) that could theoretically be recovered is equal to the absolute value of the sum of all the values of Pbrake determined in paragraph (c)(1)(i)(C) of this section, divided by 36000 (to convert 10 Hz data to hours) and rounded to the nearest 0.01 kilowatt hours.

(2) Calculate the actual amount of energy recovered (Erec) by a hybrid electric vehicle when tested on the FTP according to the provisions of this part, as follows:

(i) Measure the electrical current in Amps to and from the hybrid electric vehicle battery during the FTP. Measurements should be made directly upstream of the battery at a 10 Hz sampling rate.

(ii) At each sampling point where current is flowing into the battery, calculate the energy flowing into the battery, in Watt-hours, as follows:

(iii) The total energy recovered (Erec) is the absolute value of the sum of all values of Et that represent current flowing into the battery, divided by 1000 (to convert Watt-hours to kilowatt-hours).

(3) The percent of braking energy recovered by a hybrid system relative to the total available energy is determined by the following equation, rounded to the nearest one percent:

(4)

(i) Determination nominal voltage (Vnominal) using the following equation:

(ii) If the absolute value of the measured current to and from the battery during the measurement of either VS or VF exceeds three percent of the maximum absolute value of the current measured over the FTP, then that VS or VF value is not valid. If no valid voltage measurement can be made using this method, the manufacturer must develop an alternative method of determining nominal voltage. The alternative must be developed using good engineering judgment and is subject to EPA approval.