GM Will Offer Displacement-on-Demand Engines

Published July 1, 2003

General Motors Corporation is introducing a new engine technology that increases fuel economy without negatively affecting performance or passenger safety. The company on May 8 announced it will offer displacement-on-demand engines beginning with some of its model year 2005 vehicles.

Displacement-on-demand (DOD) enhances fuel economy by shutting down half of a vehicle’s cylinders when those cylinders are not needed. Current engine technology sends fuel to every cylinder regardless of whether all are contributing to performance at a given time.

Typically, all of a vehicle’s cylinders are employed while accelerating from a standstill, climbing a hill, or passing traffic. At a steady cruising speed, DOD vehicles would run on only half their cylinders, increasing fuel economy by nearly 10 percent.

Past efforts to improve fuel economy have come at significant cost to performance and safety. Efforts to save fuel by downsizing engines have been rejected by consumers, who typically prefer more powerful, responsive engines. Efforts to save fuel by building lighter vehicles have endangered drivers and passengers, as lighter materials are less crashworthy. USA Today has reported that 7,700 people have died for every mile-per-gallon improvement in fuel economy.

GM said it will offer DOD on the 2005 midsize Chevy TrailBlazer, GMC Envoy XL, and GMC Envoy XUV sport utility vehicles. In 2006, GM will offer DOD technology for several midsize passenger cars. By 2008, GM predicts, a wide variety of its vehicles–including more than 2 million vehicles on the road–will be equipped with DOD technology.

James M. Taylor is managing editor of Environment & Climate News. His email address is [email protected].