You think people started buying smaller cars because of the CAFE standards?
Do they have a choice now?
Some people, yes. CAFE raises the price of large cars and subsidizes the price of small cars. Some people are driven by fuel prices and gas mileage but for many the price of the car drives the purchasing decision.
A big car is expensive and in the US we don’t even have very many big cars. We now have big trucks that masquerade as cars because trucks have different, lower, CAFE standards.