Although gas prices are extremely high at the moment, I think it would be in America's best health Internet to just instate a gas tax instead of raising CAFE standards. The amount of poison that would be allowed in the air by CAFE raising would be extremely harmful to America's health, so if putting a tax on gas is an option that sounds like a smarter idea.
When CAFE standards were put into place the idea was improve the availability of fuel efficient cars to the American public. Allowing the CAFE standards to remain the same and instead imposing a new federal fuel tax would not do anything to increase the availability of fuel efficient cars. The only thing that would be accomplished is a new revenue stream for the federal government.