Two-mode, hybrid-electric propulsion system

The Sierra 1500 Hybrid system is comprised of a gasoline-fueled Vortec 6.0L V8 engine as well as a patented two-mode electric system. This system allows Sierra 1500 Hybrid to launch from a stand-still in all-electric mode and continue at speeds up to 30 mph (48 km/h). The system also allows the V8 motor to operate more economically, in V-4 mode, at higher speeds. V-4 mode is where the gasoline-powered engine uses half of its cylinders to provide vehicle power. 

Overall, the hybrid system relies on a specifically designed Electrically Variable Transmission, a 300-volt nickel-metal hydride Energy Storage System and the 6.0L V8 engine. The Hybrid Optimizing System helps determine the most efficient way to power Sierra 1500 Hybrid, based on driving conditions, powertrain performance and other vehicle systems operation. The vehicle can travel on gasoline alone, electricity alone at lower speeds, or a combination of the two, for optimal efficiency.