Corporate average fuel economy (CAFE) standards are regulations in the United States, first enacted by the United States Congress in 1975,[1] after the 1973–74 Arab Oil Embargo, to improve the average fuel economy of cars and light trucks (trucks, vans and sport utility vehicles) produced for sale in the United States. -- https://en.wikipedia.org/wiki/Corporate_average_fuel_economy
CAFE was adopted in 1975 and effective from 1978. Are you confusing "modern CAFE regulations" with the late 2000s narrowing of the "car" and "light truck" CAFE regulations (which, yes, did push automakers to try to push more vehicles that fell out of the "light truck" category, just as the earlier standards pushed from cars to light trucks), which has effectively shifted back the old gap after the actual (and more complex) modern (2011+) regulations came into play.
We had entire news cycles about the size of the Ford Excursion and GM's Hummer 1 back in the day.