The 2008 GMC Sierra adds a new off-road themed model. These large trucks were redesigned for the 2007 model year along with the similar Chevrolet Silverado. Sierra offers regular, extended, and crew cab body styles. Extended cabs have rear-hinged back doors that don't open independently of the fronts. Regular cabs can seat up to three passengers, while extendeds and crews can seat up to six. Available cargo bed lengths are 6.5 and 8.1 ft for regular and extended cab models and 5.8 ft for crews. The 2008 GMC Sierra offers two interiors, dubbed "Pure Pickup" and "Luxury inspired." Available engines, depending on cab/bed configuration, are a 195-hp 4.3-liter V6, 295-hp 4.8-liter V8, 315-hp 5.3-liter V8, and 367-hp 6.0-liter V8. Some versions of the 5.3 V8 can run on E85 ethanol fuel. That engine and the 6.0 V8 have GM's Active Fuel Management cylinder deactivation. All these engines pair with a 4-speed automatic transmission. Unique to the Sierra lineup is the top-end Denali. It's a crew cab with a 403-hp 6.2-liter V8 and a 6-speed automatic transmission. Maximum towing capacity is 10,500 lb. Rear-wheel drive is standard. Two 4WD systems are available: a part-time setup that should not be left engaged on dry pavement and GM's Autotrac that can. Both include a low-range gear for off-roading. Sierra Denali has all-wheel drive without low-range gearing. Four suspensions are available. Z83 and Z85 are designed for optimum ride comfort. Z60 is a street-performance setup designed for maximum handling capability. Z71 is designed for off-roading. Available safety features include ABS, traction control, antiskid system, and curtain side airbags. The 2008 GMC Sierra All Terrain is a new package that includes the Z71 suspension and specific interior and exterior trim.