Powertrain details

The GMC Sierra All Terrain HD concept is propelled by the new, production 6.6L Duramax turbo-diesel V-8 and Allison 1000 six-speed automatic transmission powertrain combination offered in the 2011 Sierra HD trucks. The Duramax is rated at 397 horsepower (296 kW) and 765 lb.-ft. of torque (1,037 Nm).

The powerful 6.6L Duramax is more fuel-efficient - with up to 11-percent greater fuel economy than previous versions - and reduces NOx emissions by up to 63 percent. The powertrain's efficiency is assisted by the Allison 1000 transmission, which requires less engine power to funnel torque to the axles. It also incorporates a "smart" exhaust brake feature that helps save wear on the brakes on downhill grades, a feature available on production Sierra HDs.

With the same proven powertrain as production Sierra HD trucks, the All Terrain HD delivers comparable hauling and towing capabilities, including:

Estimated payload capacity of 2,700 pounds (1,225 kg) Estimated conventional towing capacity of 13,000 pounds (5,896 kg) Estimated fifth-wheel towing capacity of 15,600 pounds (7,076 kg).

The GMC Sierra All Terrain HD also features four-wheel drive, with automatic locking front and rear differentials, while the 14-inch, four-wheel disc brake system from the production Sierra HD provides the stopping power for this unique off-roader.

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