General Motors has announced that the 2005 GMC Envoy XL, Envoy XUV and Chevrolet TrailBlazer EXT will be the first vehicles to showcase its latest Displacement on Demand fuel-saving technology. Displacement on Demand will be a standard feature in the vehicles' optional Vortec 5300 V8 engine. The more efficient engine will boost the fuel efficiency of these vehicles by about 8% (based on an EPA testing procedure).