The new standards require American automakers to increase fuel economy so that, across their product lines, their passenger vehicles would average 65 miles per gallon by 2031, up from 48.7 miles today. The average mileage for light trucks, including pickup trucks and sport utility vehicles, would have to reach 45 miles per gallon, up from 35.1 miles per gallon. Selling electric vehicles and hybrids would help bring up the average mileage per gallon across their product lines.
There’s no reason to think the weight premium is here to stay. Going much over 350 to 400 miles of range isn’t really necessary, and there many models reaching that already. All further improvements in Wh/kg can go towards reducing weight, not increasing range.