All of this assumes that CO2
All of this assumes that CO2 is a climate driver, but evidence says it's likely a climate follower, rising AFTER warming, not before. Even those climate scientists who promote man-made global warming admit that CO2 is a low-impact greenhouse gas. Simple physics say that the more CO2 you put in the atmosphere, the lower its per-cubic meter impact is.
Which shatters the premise that CAFE or other reduction standards targeting CO2 will have any impact whatsoever on climate.