The GMC Sierra All Terrain HD concept is an exploration of heavy-duty truck capability combined with greater off-road versatility. It is highlighted by a bold exterior design, enhanced all-terrain suspension and premium details expected of a GMC - all designed to enable greater access to off-road destinations.

The new 2011 Sierra HD underpins the All Terrain HD concept, with a modified, production-based 4WD chassis and the Duramax diesel/Allison 1000 six-speed powertrain. The enhanced suspension and unique body dimensions, including increased ground clearance and wider track, as well as greater approach/departure angles, deliver off-road capability while maintaining HD levels of payload and trailering capacity.

"The Sierra All Terrain HD concept takes GMC's outstanding new HD platform to the next level, marries it to the legendary Duramax diesel/Allison transmission, and provides a heavy-duty expression of GMC's premium All Terrain package," said Lisa Hutchinson, GMC product marketing director. "It delivers the exceptional capabilities of the Sierra HD - hauling, towing and performance - and applies them to the toughest driving environments. It's the ultimate professional-grade tool for construction crews, ranchers and adventurers whose activities aren't limited by where the pavement ends."

The GMC Sierra All Terrain HD features a unique five-foot, eight-inch Crew Cab/short box body configuration that supports a wheels-at-the-corners proportion. Shorter in overall length than production Sierra HD models, the concept's dimensions contribute to greater approach/departure angles. Additional off-road elements include:

Wider, 73-inch (1,853 mm) track for greater stability Approximately 3 inches (76 mm) greater ground clearance Custom front upper and lower control arms Specially constructed Fox off-road shocks with remote fluid reservoirs (integrated in the wheel house liners) Front and rear jounce shocks Electronic front stabilizer bar disconnection 35-inch-tall BFGoodrich KM2 "mud terrain" tires mounted on 20-inch machined aluminum wheels Full composite underbody protection.

"The capability-enhancing attributes of the GMC Sierra All Terrain HD build on the already outstanding capabilities offered in the all-new production Sierra HD trucks," said Hutchinson. "Although it is strictly a concept, it is a pretty realistic one."

• Purposeful design
• All Terrain chassis and suspension
• Powertrain details