GMC will introduce the 2009 Sierra Two-Mode Hybrid pickup truck at the Chicago Motor Show this week, and will unveil a hybrid pickup concept called the Denali XT. The sleek, four-door concept is based on GM’s Zeta rear-wheel drive architecture, which will also be utilized on the 2008 Pontiac G8 sedan and the 2009 Chevrolet Camaro.

The new 2009 GMC Sierra Hybrid, which goes on sale in late 2008, is yet another production application of General Motors’ full hybrid system. It achieves 40 percent greater city fuel economy, and a 25 percent improvement in overall fuel economy, compared to its gas-powered counterpart. It also grants a hefty 6,100-pounds of towing capacity—decent but still a far cry from the standard GMC Sierra’s 10,500 pounds of hauling power.

The Sierra Hybrid will be offered in the Crew Cab body style on both two-wheel drive and four-wheel drive models. GMC is claiming that the hybrid pickup can stay in all-electric mode up to 30 miles per hour, drawing energy from its 300-volt battery pack. Gas power comes from a 6.0-litre V8 outfitted with “Active Fuel Management Technology,” which allows the vehicle to shut down four of its available eight cylinders in lighter duty driving. Prices have not been announced.

The Denali XT is the first time GM has placed its two-mode hybrid system in a vehicle capable running on an 85 percent blend of ethanol. Power will come from a new, downsized, 4.9-liter version of GM’s small-block V8. The truck also features cylinder deactivation for further fuel reduction. The carmaker is promising a 50 percent improvement in fuel economy over production pick-up trucks of similar size.

The Denali XT is driven by all-electric propulsion at low speeds, but offers plenty of highway and towing performance from its fixed-gear configuration. It has an estimated payload capacity of 1,100 pounds and a towing capacity of 3,500 pounds.