Stringent fuel economy regulations imposed on cars in the 1970s had made it practically impossible for automakers to keep selling big station wagons. Yet many Americans still wanted roomy vehicles.

The answer, Mr. Sperlich and Mr. Iacocca realized, was to make family vehicles that were regulated as light trucks, a category of vehicles that includes pickups. The government had placed far more lenient fuel economy rules on light trucks, as well as more lenient safety and air pollution standards.

Cargo vans, a tiny niche marketed to carpenters, plumbers and other workers, were regulated as light trucks. When Chrysler introduced the minivan in 1983, fewer than 3 percent of them were configured as cargo vehicles, with just a couple of seats in the front and a long, flat bed in the back.