Back in the '90s, a way was found around the gas mileage mandatory minimums (CAFE, or Corporate Average Fuel Economy regs) imposed by the federal government on new cars – which had the effect of making cars smaller and smaller-engined, a kind of shrinflation of transportation – by building SUVs instead.

These were a new category of vehicle not encompassed by the federal gas mileage mandatotry minimums, which were only applicable (at the time) to passenger cars. Light trucks – models like the Ford F-series and GM's Silverado, etc – were not required to "comply" with these MPG minimums because (at the time) a degree of reason still held sway and it was understood that while cars were fundamentally about A to B transportation, trucks were fundamentally about work that needed to get done – and it is hard to do much work with a downsized, front-wheel-drive (and four cylinder-powered) "truck."

They were allowed to remain proper-sized, rear-drive/4WD and could still be equipped with the V8 engines that had been largely disappeared (along with rear-drive and body-on-frame construction) from the passenger car market, courtesy of the MPG minimums.

An "SUV" was a truck with an enclosed and carpeted bed turned into additional passenger-carrying space. People bought these "SUVs" in droves – because they were fundamentally the same things as the passenger cars they were no longer able to buy – courtesy of the regulatory de facto ban on full-sized, rear-drive, V8-powered cars.

Naturally, the government saw – and closed – the "loophole" and that is why SUVs are now being downsized, too.