In 2011, Obama announced an agreement with major automakers to raise fuel efficiency standards to 54.5 miles per gallon. The target, the administration said, would save motorists $1.7 trillion in fuel costs over the life of the vehicles, but cost the auto industry about $200 billion over 13 years.
The EPA said in July that because Americans were buying fewer cars and more crossovers, SUVs and trucks, it estimated the fleet will average 50.8 mpg to 52.6 mpg in 2025. In November, the agency moved up the timetable for proposing that automakers can meet the 2025 standards.
McCarthy said her determination, a legally binding decision to maintain the fuel efficiency rules, rested on an extensive technical record. She said the rules are "feasible, practical and appropriate" and in "the best interests of the auto industry."
Sen. James Inhofe, R-Okla., on Wednesday said McCarthy's determination was an "extreme action" that "broke the deal" with automakers.
Legal experts have said it will be more difficult for the Trump administration and Congress to undo the determination than to unwind other regulatory actions issued by the Obama administration during its final months in office.
The 2025 determination is not a new regulation, so the EPA under Trump would likely have to go through an extensive process before withdrawing it and could face lawsuits from environmental groups if that step was taken.
Separately. California's new Democrat Senator Kamala Harris asked Pruitt whether he would commit to upholding the California waiver. Pruitt did not say outright that he would uphold the waiver, which allows California to pursue its own emission standards that are more stringent than the federal rules.
