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.
I think that would leave too many loopholes open. I think the most effective path would be to:
Schedule a progressive increase in fuel prices: End subsidies on fossil fuels Implement a tax that reflects the environmental damage caused by fossil fuel use. Add on a tax that provides remediation of historical fossil fuel damages.
Take that schedule, add it to the purchase and maintenance costs of a vehicle, and require reporting this total cost of ownership as the most prominent figure in all advertising.