On Friday, the Environmental Protection Agency announced that it had finalized the rules governing fuel efficiency for vehicles made until 2025. The rules ratchet up the fuel efficiency numbers that automakers must meet over the span of the next eight years. By 2025, automakers will have to hit an overall 51.4 mpg average efficiency rating for their fleet, which translates to about 36 mpg in real-world driving conditions—a bump of 10 mpg from what US fleets get today.

The decision comes just a week before the Trump administration takes office. President-elect Donald Trump has not commented on the EPA’s fuel efficiency guidelines, but automakers had been hoping that the EPA would delay signing off on this rule so that his administration might relax fuel efficiency standards out to 2025. Trump has denied the existence of climate change—a factor in the EPA’s fuel efficiency decisions—despite the preponderance of evidence showing that climate change is real and human-caused.

Although a Trump administration could reverse the EPA’s new rules, doing so will be significantly harder than if the EPA had left the process for finalizing its December recommendations up to the new administration.

Automakers expressed their concern in December, when the EPA made its first move to finalize these rules. But the EPA countered that this rulemaking has been in the works for years, involving extensive reviews to show that automakers could technically and economically meet the requirements. The EPA argued that this keeps the US on track with fuel efficiency goals in Canada and Europe and that automakers in the US had already exceeded earlier projections for fuel economy standards by 2016.

In a statement, the EPA said, “Retaining the current standards preserves the significant cuts in harmful carbon pollution expected from the original standards, and provides regulatory certainty for this global industry that must meet similar standards in other markets including Canada and Europe.”

According to Bloomberg, a new EPA would have to “initiate and complete a new rulemaking to change the current standards, which were codified in 2012. And then it would have to defend scrapping eight years of technical analysis in court.” Still, Trump has appointed Oklahoma Attorney General Scott Pruitt (who has deep ties to the fossil fuel industry) to head the next EPA, meaning that the political will to overturn the Obama administration’s EPA rules might be there.

Pruitt’s leadership was picked with the help of Thomas Pyle, president of the American Energy Alliance (AEA). In a statement today, AEA spokesperson Chris Warren wrote, “We look forward to the Trump administration taking a more level-headed approach that puts fuel economy standards in line with the needs of American families.”