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US DOE reduces CAFE fuel economy values for electric vehicles

23 June 2026

The US Environmental Protection Agency (EPA) issued a ‘Dear Manufacturer’ letter, advising electric vehicle manufacturers that, in their CAFE reporting for model year (MY) 2026, they should use reduced petroleum equivalence factors (PEF) established by the Department of Energy (DOE) in an interim final rule finalized in February [6783].

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While EVs were considered zero-emission vehicles for the purpose of the (now repealed) EPA GHG emission regulations, they are not considered zero-fuel-consumption vehicles for the purpose of NHTSA CAFE regulations. Under CAFE, fuel economy of electric vehicles is calculated using the PEF factor, established by the DOE.

In a 2024 final rule [6335], the DOE established a PEF = 82,049 Wh/gal for MY 2024-2026 EVs (without any petroleum-powered accessories). In the 2026 interim final rule, the PEF factors for MY 2026 and later vehicles have been reduced to:

These lower PEF values significantly reduce the CAFE fuel economy values of electric vehicles and reduce the manufacturers’ ability to lower the average fuel economy of their vehicle fleet by producing more EVs (and/or their ability to generate CAFE credits for EVs).

Under the 2026 calculation, an EV that consumes 265 Wh/mile in urban driving (FTP-75, 55%) and 220 Wh/mile in highway driving (HWFET, 45%)—with an average electrical energy consumption of 244.75 Wh—has a petroleum-equivalent CAFE fuel economy of (12,307 Wh/gal)/(244.75 Wh/mile) = 50.28 mpg. Under the prior, 2024 calculation, the same EV would have a petroleum-equivalent fuel economy of 335.24 mpg.

Source: US EPA