2009 GMC Sierra Hybrid

A Hybrid That Hauls

The GMC Sierra Hybrid is a gas-electric pickup truck that promises enhanced fuel economy without a significant drop in utility.

The GMC Sierra has long been useful for drivers who need to tow boats or carry heavy loads, but with a large V8 engine, it is not particularly fuel efficient. Soon General Motors will give its pickup drivers the option to go green with another application of its new two-mode hybrid system in the 2009 Sierra Hybrid.

The Sierra Hybrid promises 25 percent better overall fuel economy than the non-hybrid Sierra pickup, and up to 40 percent better mileage in city driving. It will be available with either rear- or four-wheel drive, but only in a “Crew Cab” body style, which means it will have four doors and two rows of seats.

The only visible differences on the outside are aerodynamic modifications to the front air dam and the addition of a cargo-bed cover, both of which improve the Sierra Hybrid's aerodynamics. At the heart of the hybrid powertrain is a 6.0-liter V8 engine coupled with an electrically variable transmission that features four fixed mechanical gear ratios and two electric motors. Amazingly, it is about the size of a conventional automatic transmission.

A 300-volt battery pack located under the rear seat powers the electric motors. Like other two-mode hybrids, the Sierra Hybrid can drive up to 30 mph on electric power alone. In situations where more thrust is required, such as when towing, V8 power can be delivered straight to the wheels like on a traditional heavy-duty pickup truck. In normal driving conditions, electric and gasoline power work together for greatest efficiency. To save more fuel, the gas engine shuts off when at a stop and features Active Fuel Management, which allows it to run on four cylinders in low-load situations.

The Sierra Hybrid’s two-mode hybrid powertrain is also used in GM’s full-size SUVs, the Cadillac Escalade Hybrid, Chevy Tahoe Hybrid and GMC Yukon Hybrid.

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