Answer
The Corporate Average Fuel Economy (CAFÉ) standards
Step-by-step explanation
This regulation was able to push automakers to increase vehicle fuel economy that in turn led to saving of money and cutting down the rates of pollution. For example in 1975 before the first mandated CAFÉ standards by the congress , the average American car traveled 13.5 miles per gallon, but by 2016 fuel economy was doubled to 25 miles per gallon.