From left, Environmental Protection Agency administrator Scott Pruitt, Ford CEO James Hackett and Trump. "Obama's EPA cut the midterm evaluation process short with politically charged expediency, made assumptions about the standards that didn't comport with reality and set the standards too high".

Transportation Secretary Elaine L. Chao also said the new rule creates more "realistic standards" that will bring "newer, safer, cleaner and more fuel-efficient vehicles" to the roads.

The public will have 60 days to provide feedback once the NPRM is published at the Federal Register. The agencies said they expect to issue a final decision this winter. She did agree, though, that some easing of the fuel economy requirements was needed but nothing as drastic as the Trump administration's proposal. More details can be found on the NHTSA's website here and the EPA's website here.

Heidi King, the deputy administrator of the National Highway Transportation Safety Administration, said the administration is excited about the idea of getting more modern cars on the road to replace older, less efficient ones.

A $2,340 reduction in overall average vehicle ownership costs for new vehicles ($1,850 reduction in the average required technology costs and $490 reduction in ownership costs for financing, insurance, and taxes). Environmental groups who support the gas mileage standards, consumer advocacy groups, and medical associations that aimed to reduce air pollution slammed the proposal.

The problem is that many consumers are trading in fuel-sipping small cars for less fuel-efficient SUVs as gas prices remain low.

That's "laughable", said Robert Weissman, president of watchdog group Public Citizen, in a statement.

US President Donald Trump's administration announced plans on Thursday to roll back Obama-era fuel efficiency standards, sparking a fight with California and other states that favor more aggressive environmental policies. "That claim gives fig leaves a bad name". Under the Clean Air Act, California has the right to set stricter standards, and other states may adopt those standards.

The administration wants to freeze a rule mandating that automakers work to make cars substantially more fuel efficient.

Weissman said the "the Trump administration's rollback of clean auto standards is a disastrous wreck for consumers and the planet" and said it will force Americans "to pay more at the pump and breathe dirtier air". "This latest move by the Trump administration means that our cars will continue to pump billions of metric tons of carbon pollution into the atmosphere, further destabilizing the climate and sparking increasingly severe impacts of global warming".

Two trade groups - the Alliance of Automobile Manufacturers and Global Automakers, which together represent General Motors, Ford, Fiat Chrysler, Toyota, Kia and other major domestic and worldwide automakers - said they supported the process outlined Thursday. But Andrew Wheeler, the acting chief of the EPA, told lawmakers on Wednesday that he doesn't want the federal standard to contradict states that want to require higher gas mileage. They said they expected it would "ensure fuel economy standards are based on the best available data and reflect marketplace realities".

He said in a statement that the organization would challenge the administration's action "in the court of public opinion and the court of law".

A significant body of ICCT research built up over several years, most of it done in close collaboration with USA and global automotive suppliers, has validated the rigorous and meticulous analyses previously done by EPA and California Air Resources Board staff on which the vehicle efficiency standards that the administration now seeks to dismantle were founded.

"Automakers support continued improvements in fuel economy and flexibilities that incentivize advanced technologies while balancing priorities like affordability, safety, jobs and the environment", the Alliance of Automobile Manufacturers, which represents major auto companies on US policy issues, said in a statement. "The California Department of Justice will use every legal tool at its disposal to defend today's national standards and reaffirm the facts and science behind them".