Vehicle Overview
While mechanically identical to the Chevrolet Silverado heavy-duty models, GMC positions the Sierra 2500HD/3500HD to appeal to a more upscale customer. There's a little more flash on the outside and a little more elegance on the inside. But the real selling point for the Sierra is the same as the Silverado: the combination of a Duramax diesel and Allison six-speed automatic transmission.

The Sierra 2500 heavy-duty trucks come in Work Truck, SLE and SLT trims and are available in the following configurations: regular cab long bed, extended cab standard bed, extended cab long bed and crew cab long bed. The 3500 models come with only the long bed, but dual-rear-wheel versions are available. All HD trucks can be ordered in two- or four-wheel-drive. The standard powertrain is a 6.0-liter gas engine and six-speed Hydra-Matic automatic transmission, while the diesel is optional. GM says the 2500HD and 3500HD can tow up to 13,000 pounds with the diesel engine and a conventional hitch. The maximum towing capacity with a fifth-wheel hitch is 16,700 pounds; payload varies between 2,331 pounds and 5,309 pounds, depending on the model.

New for 2009
OnStar now comes with Turn-by-Turn Navigation and Destination Download. Bluetooth is also added, and XM Satellite Radio is enhanced with a NavTraffic feature. To help drivers with hitching trailers or spotting obstacles behind them, the Sierra HD offers a rearview camera system.

The Sierra heavy-duty trucks are visually distinct from their Chevy cousins and Sierra 1500 models. The grille opening is more pronounced, and the headlamps and hood are different. GMC has made noticeable improvements in the overall fit and finish of the body panels; tolerances are closer, and there's less space between the cab and cargo box for a smoother design. Even the dually has integrated, hydroformed steel fenders. Fog lamps on the SLT models are set into the bumper for an upscale appearance.

Exterior features include:
  • All models have chrome bumpers
  • Available moonroof on extended and crew cabs
  • Available EZ Lift tailgate
  • Tow mirrors available
  • Side, roof markers on dually models

The GMC interior themes found on the Sierra 1500 carry over to the heavy-duty models. The Work Truck and SLE trims feature more work details, while the SLT is more luxurious. The most obvious difference is the dash design. The Work Truck has a double glove box and the SLT has a single glove box. The Work Truck has armrest storage built into the 40/20/40-split bench seat, and there's also a lockable storage bin large enough for a laptop under the center-seat section. Premium interiors have a large center console with 20.1 liters of undivided storage. GMC offers a wide range of audio options with a Bose sound system available in premium models.
  • LED-lit analog gauges
  • Available rear-seat DVD player
  • Power-adjustable foot pedals
  • Available power rear window on extended and crew cabs
  • Stadium-style seating in second row

Under the Hood
  • 360-horsepower, 6.0-liter V-8, with iron block and aluminum cylinder head, cam-in-block, two valves per cylinder, making 380 pounds-feet of peak torque mated to a six-speed Hydra-Matic automatic transmission
  • 365-hp, 6.6-liter V-8 diesel, with iron block and aluminum cylinder head, cam-in-block, four valves per cylinder, making 660 pounds-feet of peak torque mated to a six-speed Allison automatic transmission

The story here is what's missing, not what's available. GM's electronic stability control system, StabiliTrak, is available only on select 2500HD models. Also, side-impact and side curtain airbags are not available. Other safety features include:
  • Dual front airbags standard
  • OnStar gets Turn-by-Turn Navigation
  • Ultrasonic rear parking assist available
  • Four-wheel antilock brakes

Of Interest to Truck Owners
  • Maximum gross vehicle weight rating: 9,200 pounds (all models)
  • Maximum payload capacity: 3,924 pounds (regular cab 4x2, 6.0-liter V-8)
  • Maximum towing capacity: 13,000 pounds (regular, extended and crew cabs, 6.6-liter V-8)
  • Fuel tank capacity: 26 gallons (with 6.5-foot bed)
  • Minimum ground clearance: 9.5 inches