General Motors Corp. will put at least two million vehicles on the road by 2008 with new engines that incorporate technology to improve fuel economy by as much as 8 percent, according to the Detroit News. A computer in the engines senses how much power a vehicle requires and seamlessly disables or engages half or all of the cylinders without any action from the driver, the News repoted. This process is known as displacement on demand. "Like a symphony conductor, (the computer) has to be capable of commanding the right things," GM powertrain engineer Dick Michalski told the News Oct. 28 at the GM Technical Center in Warren. Beginning in model year 2005, according to the News, GM's new Gen IV Vortec 5300 8-cylinder engine will be available with displacement on demand in the Chevrolet TrailBlazer EXT, GMC Envoy XUV and GMC Envoy XL -- all extended length sport utility vehicles. "I think it's a foot in the door, a step in the right direction," David Friedman of the Union of Concerned Scientists said of GM's effort, according to the News.