The reigning champion of cautionary V-8 technology tales is, of course, Cadillac’s V8-6-4 “displacement on demand” engine. Dubbed the L62, it was deployed across the automaker’s entire 1981 lineup and was touted as the last word in delivering both power and efficiency in the same package.
The thinking was simple: design an engine that could turn its cylinders off, in pairs, when they weren’t needed, thus cutting down on the amount of fuel being consumed during simple cruising. If this sounds familiar, it’s because General Motors revisited the concept in the 2000s with greater success.
At the time, however, computer controls simply couldn’t handle the complex range of variables that presented themselves during basic driving and thus could not be relied on to properly drop and pick up cylinders as needed. Despite boasting hundreds of thousands of calculations per second from the hardware managing the L62 V-8, the promised 30 percent boost in fuel economy was a myth. The reality was an engine that bucked, hesitated, and otherwise made smooth driving almost completely impossible. Even at steady highway speeds, the system would snap back and forth between four- and eight-cylinder operations, alternatively soaking the cylinders with fuel and starving them.
Try as they might, Cadillac’s engineers couldn’t find a way to make the V8-6-4 system work, and after an extensive attempt at reprogramming after the engine went on sale, it was banished by the end of the model year. General Motors then gave existing owners the opportunity to have the variable-displacement system permanently disabled. Perhaps the company should have tested it under real-world conditions at some point?
