General Motors Corp. will introduce a new hybrid full-size pickup and a concept hybrid truck this week at the Chicago Auto Show, betting that pickup drivers have been itching to jump on the hybrid bandwagon. GM says the 2009 GMC Sierra hybrid gets a 25 percent improvement in fuel economy without compromising performance, while its GMC Denali XT concept - a low-slung, muscular utility vehicle - gets 50 percent better fuel economy than a comparable small pickup. The Sierra is the next large GM vehicle to get the company's new two-mode hybrid system, which has also been introduced on the Chevrolet Tahoe and GMC Yukon sport utility vehicles and the Chevrolet Silverado pickup. The sport utility vehicles are expected to go on sale early this year, while the Silverado and Sierra are scheduled to hit the market at the end of 2008. The two-mode system got a lot of buzz late last year at the Los Angeles Auto Show, where the hybrid Chevrolet Tahoe was named the 2008 Green Car of the Year by the Green Car Journal. Like single-mode hybrid systems now used by Toyota Motor Corp., Ford Motor Co. and others, the two-mode runs without the gas engine at low speeds. But at higher speeds, the electric motor in the two-mode hybrid contributes more power. The two-mode system also is better for towing. GM says the Sierra can drive up to 30 mph (48 kph) on just electricity, which is stored during braking and cruising in a 300-volt battery. When the gas engine is used, the hybrid system helps the 6-liter, V-8 engine run longer in its more economical four-cylinder mode. GM says the hybrid Sierra can tow up to 6,100 pounds (2,767 kilograms). The non-hybrid GMC Sierra 1500 can tow up to 10,500 pounds (4,763 kilograms). It remains to be seen whether pickup buyers, who have historically saved on fuel costs by choosing diesel models, will adopt hybrid systems. Hybrid systems cost more than gas engines, but pickup drivers tend to drive longer distances so they could recoup the premium more quickly. Small businesses also might want to take advantage of government tax breaks for hybrids. Mark LaNeve, GM's vice president of North America sales, service and marketing, has said the company expects about 5 percent of pickup drivers to opt for the hybrid system. But he said GM will be able to ramp up production if there's more demand. GM sold 208,243 Sierras in 2007. GM's radically redesigned Denali XT concept is built on a car-like unibody frame, rather than a truck frame, for a smoother ride and better fuel economy. It's the first vehicle from GM that combines an ethanol-capable engine with the two-mode hybrid system. The Denali XT comes on the heels of another compact hybrid truck concept, the Toyota A-BAT, which was introduced at last month's North American International Auto Show in Detroit. The A-BAT is also built on a unibody frame and has a 4-foot (1.2-meter) bed, 7 inches (18 centimeters) shorter than the Denali XT's 55-inch (140-centimeter) bed. The Chicago Auto Show opens to the public next Saturday after two days of media previews.