The front of the GMC Sierra emphasizes the truck's wide stance. The GMC emblem is set amid dark horizontal bars in the middle of an upright and chrome-surrounded grille. The headlamps are a pair of stacked, jeweled lenses. The front bumper features round fog lamps and a wide air intake and wraps around the sides of the truck to the front lower edge of the front wheel wells.
Top trim levels get some distinguishing features. The Denali gets its own chromed grilles, both the upper section and the air vent below the front bumper, and the bumpers are painted to match. Hybrid models are festooned with odd-looking H badges.
The Sierra hood has a pair of long, narrow V-shaped power bulges and leads back to a steeply raked windshield. The windshield is tilted back for improved aerodynamics and enhanced highway fuel economy.
The side view features slightly bulging and elongated fender flares that sweep down behind the headlamps. The sides of the cargo bed are higher than on previous models, and the exterior of the tailgate is sculpted, enhancing the rear view of the truck. Stacked tail lamps are on either side of the tailgate.
A cargo management system is available for the bed with side rails and various cargo-carrying and cargo-controlling boxes and dividers and tie-downs.
The GMC Sierra and Chevy Silverado are built on the GMT900 platform that debuted in 2007 and shares many underpinnings with the Yukon, Suburban, and Tahoe SUVs. The pickups get a unique rear suspension and stiffer rear frame section. The Sierra and Silverado share mechanical components, with the exception of the unique features found on the Sierra Denali.
Compared with the previous-generation models, the current frame is much stiffer in all directions. This stiffness contributes to a smoother ride and better handling. It also allowed the engineers to reduce the gap between the truck bed and passenger compartment as well as the gaps between fenders and bumpers, all of which enhances aerodynamics and fuel efficiency.
The front suspension uses a coil-over-shock setup and the rack-and-pinion steering gear is mounted to the engine cross-member frame. The truck also has a rear axle design with shock absorbers mounted outboard and more upright for better dynamic control.
Fuel economy ratings, except for Hybrids, run 12-15 mpg City, 18-21 mpg Highway. When using E85 those numbers drop dramatically. The XFE (Xtra Fuel Economy) models with a 5.3-liter V8, 6-speed automatic and axle ratio of 3.08:1 increase EPA ratings from 15/21 to 15/22 mpg City/Highway. Proprietary XFE pieces include aerodynamic upgrades in the form of a soft bed cover and extended front air dam, plus aluminum wheels (including the spare) and lower front suspension arms, locking rear differential, and low rolling resistance tires. A trailering package is standard so XFE models can tow up to 7000 pounds.
Two types of interiors are available. The GMC Sierra SLT boasts interior features popularized by the Yukon sport utility, providing a much more upscale environment for the driver and passengers. GMC hasn't forgotten about owners who use their trucks for work, however. So the other Sierra models use a pure pickup interior with more function, like dual glove boxes, and less luxury.
The pure pickup, as it's called, has a unique dashboard that is more driver-oriented and has large switchgear and door handles that are designed to be easily manipulated by those wearing work gloves. The pure pickup interior includes a 40/20/40 split front bench seat with the center section folding down to provide a large storage compartment and wide armrest.
The SLT's SUV-style luxury-oriented interior puts audio and ventilation system controls more easily within reach of the front-seat passenger and has two front bucket seats with a fixed center console with assorted storage compartments.
Either dashboard sports full analog instrumentation, and may have more information available through digital display. Operating controls are GM simple, especially on the pure pickup, while on the top-line models the central dash has many small white-on-black buttons that may require a short learning curve. Some drivers report peculiar ergonomic details as the steering wheel is slightly offset from the seat centerline (which is not uncommon).
Rear seating is provided for three people in the Extended and Crew Cab versions. With 34.3 inches of rear legroom in the Extended Cab, space is comparable to the competitions'; but the Sierra Crew Cab, with only 39.0 inches of rear legroom, comes up 1.4 to 5.5 inches short of the largest cabs offered by the Ford F-150, Nissan Titan, Dodge Ram and Toyota Tundra. The Sierra Crew Cab's rear seat is split 60/40 and can folded up individually for a flat load floor; this arrangement is also standard on some extended cabs and optional on others, depending on trim level.
Access to the rear seating area of the Extended Cab is eased by rear-hinged doors that open to nearly flush with the bed sides. Sitting in the back seat of the Extended Cab is made more pleasant thanks to the fact that the windows in the rear access doors power fully down.