If you think GM pioneered cylinder deactivation, guess again


Miss those tasty gobs of smooth, unfettered torque from an American V-8? Thank the Corporate Average Fuel Economy mandate enacted by Congress in 1975. The law set minimum fuel economy standards for new cars beginning in 1978, before doubling them to 27.5 mpg by 1985. The law wasn’t enough to kill the V-8, which also survived the arrival of the 2007 Energy Independence and Security Act, which dictated automakers deliver a combined average fuel economy of 35 mpg for all cars and trucks by 2020.

This is a companion discussion topic for the original entry at https://www.hagerty.com/articles-videos/articles/2018/02/07/gm-pioneered-cylinder-deactivation


I recall my first encounter with cylinder dropping. I was working for International Harvester in the early 80s I think it was the DV550, the predecessor to the 9 liter. This was a large heavy V8 diesel which mechanically did the same think. It was a nightmare and in my opinion a failure. Only saw one and found out why they weren’t a success.


FYI, it was the 2007 GM trucks that got cylinder deactivation, or active fuel management in GM speak, Not 2005.


The 2005 mid-size SUVs featured what was then called “Displacement on Demand” in select models like the Trailblazer EXT. The name was changed to Active Fuel Management for the 2007 GMT900 full-size SUVs, which went on sale in early 2006. We’ve updated the story to mention the change in system name.