Transportation Secretary Sean Duffy says Biden-era fuel economy standards for gas-guzzling cars and trucks are illegal and moved to reverse the rules.

New vehicles sold in the U.S. will have to average about 38 miles per gallon of gasoline in 2031 in real-world driving, up from about 29 mpg this year, under new federal rules unveiled Friday by the Biden administration.

Advocates for the self-driving vehicle industry are asking Congress to expand their ability to test and eventually sell autonomous cars and trucks.

Biden likely will make the standards stricter than Trump but not as strict as Obama and automakers will have to sell more battery-powered vehicles to meet those standards. At present, there are about 20 fully electric vehicles on sale in the U.S. with dozens more on the way. This year, the consulting firm LMC Automotive expects U.S. consumers to buy around 218,000 fully electric vehicles — about 1.5% of new vehicles sold. It's likely that negotiations between automakers, environmental groups, California and the Biden administration will produce some sort of compromise between Trump's rolled-back standards and Obama's stricter requirements. A spokesman for the Biden administration didn't return messages left seeking comment.