Just days after Donald Trump was elected president, the auto industry asked him to relax greenhouse-gas and fuel-economy standards for passenger cars and trucks. A year later, the Trump administration is reportedly about to grant that request, an action that, rather than helping the industry, will hurt its long-term competitiveness and stability.

The standards in question, put in place by the Obama administration, make cars cleaner to drive and cheaper to own. By 2025, they would nearly double fuel economy to 51.4 miles per gallon, as measured in a laboratory, which is equivalent to a real-world average of 36 m.p.g. Compared with the real-world average of 26 m.p.g. for compact and midsize cars in 2016, the standards call for an improvement of about one mile per gallon per year over the next nine years.

This fuel efficiency would result in a reduction of as much as six billion tons of carbon dioxide pollution and, through better fuel efficiency, $1.7 trillion in savings at the pump through 2025, good deals for the environment and consumers alike.

Rolling back the standards is a further retreat from the promise the United States made to the world in the Paris climate agreement and would harm public health, the environment and our international standing.