California is already swinging back:

The transportation sector is now the largest greenhouse gas emitter in the United States. That’s why enforcing strict fuel economy standards — i.e., going further with less fossil fuels — would reduce the country’s contribution to global climate change. Vehicles are also the largest source of air pollution, so reducing what comes out of tailpipes would save lives. ^[4][5]

The Obama-era standards would avert 570 million metric tons of greenhouse gas emissions by 2030, equivalent to stopping 140 typical coal-fired power plants for a year, the Union of Concerned Scientists^[6] has estimated.

They’d save consumers money too. According to Margo Oge^[7], the former head of the EPA’s Office of Transportation and Air Quality, the fuel savings alone through 2025 would add up to $1.7 trillion.

The Trump administration, however, has argued that the prior Obama standards would drain society of $500 billion^[8] over the next 50 years through increased car ownership costs and their ripple effects.

Vox’s David Roberts has written about the environmental consequences the new regulations^[9] could have if they go into effect, but it’s also worth examining the EPA’s safety rationale and how it will affect the auto industry.

In particular, the Trump administration changes would let companies like Chrysler and GM, which rank the lowest in average fuel economy^[10], breathe easier. They also cut a crucial revenue stream for carmakers like Honda that already beat the current standards and manufacturers like Tesla, which only makes zero-emission electric vehicles.

That means the weaker regulations will simultaneously help the dirtiest, hurt the cleanest, and derail years of tenuous progress in reducing environmental harm from a massive and growing source of pollution.

The EPA is justifying the fuel economy rollback by invoking safety

New cars are expensive. New cars with more features are even more expensive. Safety is a feature. So is fuel economy. But raising fuel economy standards raises the retail prices of cars. That means people with older death-trap cars will be less inclined to upgrade to newer, safer cars.