Section 474.3 - Petroleum-equivalent fuel economy calculation(a) The petroleum-equivalent fuel economy for an electric vehicle is calculated as follows: (1) Determine the electric vehicle's Urban Dynamometer Driving Schedule energy consumption value and the Highway Fuel Economy Driving Schedule energy consumption value in units of Watt-hours per mile;(2) Determine the combined energy consumption value by averaging the Urban Dynamometer Driving Schedule energy consumption value and the Highway Fuel Economy Driving Schedule energy consumption value using a weighting of 55 percent urban/45 percent highway; and(3) Calculate the petroleum-equivalent fuel economy by dividing the appropriate petroleum-equivalency factor (depending on whether any petroleum-powered accessories are installed; see paragraph (b) of this section) by the combined energy consumption value, and round to the nearest 0.01 miles per gallon.(b) For model year (MY) 2024, MY 2025, and MY 2026 electric vehicles, the petroleum-equivalency factors are as follows: (1) If the electric vehicle does not have any petroleum-powered accessories installed, the value of the petroleum equivalency factor is 82,049 Watt-hours per gallon.(2) If the electric vehicle has any petroleum-powered accessories installed, the value of the petroleum-equivalency factor is 73,844 Watt-hours per gallon.(c) For MY 2027 electric vehicles, the petroleum-equivalency factor is 79,989 Watt-hours per gallon.(d) For MY 2028 electric vehicles, the petroleum-equivalency factor is 50,427 Watt-hours per gallon.(e) For MY 2029 electric vehicles, the petroleum-equivalency factor is 36,820 Watt-hours per gallon.(f) For MY 2030 and later electric vehicles, the petroleum-equivalency factor is 28,996 Watt-hours per gallon.