The Environmental Protection Agency rejected a bid by automakers to roll back fuel efficiency standards that would sharply increase mileage by 2025, saying that the auto companies possess the technology and financial resources to meet the targets set by the Obama administration.

Citing eight years of research, EPA Administrator Gina McCarthy said that “at every step in the process the analysis has shown that the greenhouse gas emissions standards for cars and light trucks remain affordable and effective through 2025, and will save American drivers billions of dollars at the pump while protecting our health and the environment.”

The standards would result in a fleetwide average fuel economy sticker values of 36 miles a gallon by the model year 2025, 10 miles a gallon higher than the current fleet average, EPA said. If anything, McCarthy said, the standards could have been made more stringent.

The EPA decision, reaffirming the outcome of a technical report last year, is not a regulation but an “adjudication,” and therefore cannot be undone under the Congressional Review Act, according to environmentalists familiar with the decision.

“The EPA decision is disappointing,” said Gloria Bergquist, a spokesperson for the Alliance of Automobile Manufacturers. “Our fundamental priority remains striking the right balance to continue fuel economy gains and carbon reduction without compromising consumer affordability and vital auto-sector jobs.”

But environmental groups praised the EPA. “The clean-car standard is the biggest single step any nation has taken to fight oil use and global warming,” said Daniel Becker, director of the Safe Climate Campaign. “Despite dire automaker warnings that the rules would be unachievable, the car companies are now complying – making huge profits and selling record numbers of vehicles.”

The National Highway Traffic Safety Administration must still issue a five-year plan by 2018 or 2019 and Bergquist warned of a possible “regulatory collision.” But NHTSA has agreed with EPA assessments over the past few months and altering its conclusion could be difficult, Becker said.

The EPA decision Thursday marked the end of a so-called midterm review of fuel efficiency standards that were designed to reshape the efficiency of the motor vehicle fleet. In setting the standards, the Obama administration in 2012 agreed to auto industry demands that the targets be reexamined for technological and economic feasibility and possibly reset in 2017.

The technical report issued in July by the EPA and Transportation Department said there is no economic or technological barrier preventing automakers from continuing to boost fuel efficiency and to hit the standards for vehicles based on their size and footprints. It said that “a wider range of technologies exist” for manufacturers to meet targets “and at costs that are similar or lower” than those used to set the standards. The report said that so far automakers had “overcomplied” in each of three model years under the new rules, exceeding the targets by 1.4 mpg in 2014.

Becker said that the EPA had meticulously studied fuel efficiency advances in combustion engines. “This is not rocket science. This is auto mechanics,” Becker said. He said that the EPA had reached its conclusion after months of study in which the agency had taken apart engines and examined the cost of key components.

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