DETROIT — 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. But 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.

The administration last month broke off negotiations with California on fuel economy and greenhouse gas emissions, and the matter probably will be tied up in the courts for years.