By Dianne Feinstein

Originally published in USA Today.

When shopping for a new car, families have more choices available than ever before. From hybrid engines to lighter-weight materials to batteries that recharge when braking, the number of innovative technologies being deployed to increase fuel efficiency is a testament to American ingenuity.

This innovation didn’t happen by accident. It is the result of federal policies that require auto manufacturers to build more fuel-efficient cars.

But the Trump administration is now trying to rewrite those policies and undermine that progress. The Environmental Protection Agency and the Transportation Department are writing new rules that not only propose freezing the historic fuel economy standards passed during the Obama administration, they are also challenging the right of statesto impose their own ambitious standards. This would be a devastating mistake, and the administration is going to have to contend with a bipartisan law that we helped to write.

After fuel economy standards were first enacted, the auto and oil industries successfully blocked any attempt to raise them for more than three decades. We believed this was unacceptable and set out to strengthen the law. It took years of hard work to build consensus in both the House and the Senate but Congress finally passed the bipartisan Ten-in-Ten Fuel Economy Act in 2007.

Our law, signed by former president George W. Bush as part of a comprehensive energy bill, required fuel economy to increase by a minimum of 10 miles per gallon over 10 years and then be set as high as feasibly possible after that. It was the first time Congress had increased fuel efficiency in32 years.

As a result, we are now on target to exceed an average fuel economy standard of nearly 39 miles per gallon in 2020 and more than 50 mpg in 2025. This is amazing progress from where we were just a few years ago.

The stronger fuel economy standards are great news for consumers. The new technology expected in cars and trucks sold by 2025 will more than pay for itself, saving up to $4,200 over the life of the car by allowing drivers to go farther on each tank of gas.

The standards are also the largest step the federal government has taken to combat climate change. The current fuel economy standards are cutting our greenhouse gas pollution by nearly six billion metric tons. By 2030, stronger fuel standards will have cut our oil use by nearly three million barrels a day, almost as much oil as we import from OPEC nations.

And that progress hasn’t come at the expense of the car companies. Since the current standards were enacted, the auto industry has added nearly 700,000 domestic jobs and enjoyed years of record sales.

A recent 1,200-page technical analysis found that the costs of compliance for the car companies are meeting these standards more quickly and less expensively than originally projected.

The law is clear and the science is clear: The current fuel economy standards are working. They are strong and achievable.

Unfortunately, the Trump administration is choosing to ignore that overwhelming evidence. In doing so, the administration is setting itself up for a legal showdown.

Under the Clean Air Act, California has its own independent authority to reduce tailpipe pollution. More than a dozen states, including Massachusetts, have opted to follow California’s standards for greenhouse gas emissions; together they represent more than 40% of the national automotive market.

Right now, there is an agreement between the states and the federal government to use the same standards. If the Trump administration moves forward with its draft plan and diverges from that agreement by weakening the standards, it will create years of litigation and investment uncertainty, ultimately harming the very industry it claims to be helping.

Just this week, California, Massachusetts and 16 other states representing 140 million Americans brought a first lawsuit against the EPA’s efforts to roll back these standards. This will undoubtedly be the first of many legal actions if the Trump administration continues down this road. We pledge our solidarity to the states that have adopted ambitious standards and will oppose any attacks on the California waiver or on its standards.

This fight is not something the public wants. Nearly 80% of Americans believe we should be doing more, not less, to improve fuel efficiency and cut tailpipe emissions. There is no good reason to try to rollback fuel economy standards now. Trump’s misguided proposal is better suited for the junk heap.

Dianne Feinstein is a Democratic senator from California and Edward J. Markey is a Democratic senator from Massachusetts