I think it’s a well-written article but if you want to money shot so to speak…

The SUV loophole

Back in the late ’70s, the legal distinction that helped precipitate the decline of convertibles (and cars in general) seemed insignificant. A loophole the size of a needle eye. In response to the oil crisis and a burgeoning environmental movement, federal regulations went into effect in 1978 requiring automakers’ passenger car fleets to meet a fuel standard of 18 miles per gallon. But “passenger cars” meant sedans, station wagons, coupes, and convertibles.

It didn’t apply to “light trucks” such as minivans, pickups, and SUVs, the latter two of which were mostly used by farmers, contractors, and laborers who needed the extra space for hauling material. To avoid placing an economic burden on workers, light-truck fleets were subjected to lower standards. While automakers had to shrink cars to hit the fuel standard, light trucks remained spacious.

So began an emphasis on SUVs and trucks (and minivans, at least until an association with soccer moms doomed them). SUV sales increased from ~112k in 1981 to ~800k in 1987. Most Americans still didn’t need to haul anything, but they were hooked. In 1987, a J.D. Power and Associates survey even found SUV owners felt a sense of adventure while driving them — similar to a convertible.

For automakers, the economics checked out.

“You can sell a Cadillac for a lot more than a Chevy even though the Cadillac only costs marginally more to produce than a Chevy. The same thing goes for those truck-based SUVs because they’re sold as rugged,” says David Lucsko, an Auburn University professor who researches automotive history. “You can sell them at a premium and rake in the profits.”

Later, brands popularized the crossover utility vehicle, giving consumers the space of an SUV with a smoother ride. Crossovers, despite being built on the same frame as a car, are typically classified as light trucks. The takeover was complete: Light trucks outsold cars for the first time in 2002. Their sales now comprise nearly 80% of the vehicle market.