DETROIT (AP) — New vehicles in the U.S. from the 2017 model year averaged slightly better gas mileage than the previous year, rising to a record 24.9 mpg, according to an annual report from the Environmental Protection Agency.

But the mileage rose only 0.2 mpg, and environmental groups say it fell short of a 1 mpg increase required under standards enacted during the Obama administration.

To make up the difference, automakers used credits for zero emissions vehicles and other fuel-saving measures that aren't included in EPA test cycles. The agency and the Department of Transportation say that's evidence the industry will have trouble meeting standards as they rise through 2025.

The Trump administration has proposed freezing the standards at 2021 levels.

Environmental groups and the state of California say the standards should remain in place and that automakers have the technology to meet them. The administration's move to freeze them, while not finalized, already has brought a court challenge from California and other states that follow its standards.

EPA Administrator Andrew Wheeler said in a statement that the agency's proposed changes "will allow the industry to meet aggressive yet attainable standards, reduce the price of new vehicles and help more Americans purchase cleaner, safer and more efficient vehicles."

But environment groups said that even with use of the credits, the industry is meeting the standards and can continue to do so.

"While the Trump administration is moving to gut the clean car standards, its own data shows the current standards are working. Automakers are innovating and improving the performance of their fleets, and tailpipe emissions continue to plummet," said Luke Tonachel, director for clean vehicles and fuels at the Natural Resources Defense Council.