Citing Iowa, et al. v. Wright (8th Cir., 2025), DOE revised its procedures for calculating a value for the petroleum-equivalent fuel economy of electric vehicles. EPA uses this value when assessing light-duty vehicle manufacturers' compliance with DOT’s Corporate Average Fuel Economy (CAFE) standards. In a 2024 rule, the Biden Administration had determined to calculate the petroleum-equivalency factor (PEF) by multiplying four values: (1) a cumulative gasoline-equivalent energy content of electricity; (2) a fuel content factor (FCF); (3) an accessory factor (AF); and (4) a driving pattern factor (DPF). This 2024 rulemaking had noted that “the current PEF value and methodology were based on outdated data and that the technology and market penetration of EVs has significantly changed” since its 2000 inception. The Trump Administration has now restored the calculation procedure established in 2000.