What's New for 2006

For 2006, the Duramax diesel engine receives a host of power and refinement upgrades, as well as reduced emissions. The Allison automatic transmission is now a six-speed, and features a tap-shift range selection mode. The camper-style mirrors have been replaced by a folding and extending design with a built-in convex spotter glass. Trim levels and packaging have also been juggled.

Introduction

GMC's modern full-size pickup has been around in one form or another since the early '60s. Now into its sixth generation, the Sierra, as it's now called, boasts classic styling and a wide variety of body styles and drivetrains. A perennial competitor to the full-size offerings from Ford and Dodge, GMC positions itself as the professional grade truck in GM's lineup. Although its sales numbers are far below those of its competitors, when combined with its sister vehicle, the Chevrolet Silverado, the GM trucks sell in competitive numbers to Ford's F-Series.

Often first to market with exclusive features, the Sierra 2500HD continues that tradition by offering XM Satellite Radio and Bose audio systems. GMC trucks also offer the OnStar communications system that provides the convenience of 24-hour on-call assistance for everything from tow truck requests to dinner reservations. Combine this with attractive styling on the outside and thoughtful features on the inside, and the Sierra 2500HD presents a compelling package for anyone in the market for a no-holds-barred work truck. Solid as the heavy-duty Sierra is, it's definitely worth your while to shop around in this segment, as Ford and Dodge both have strong diesel power plants that give their trucks higher tow ratings. GM's truck is still a fine choice for use around the worksite and home, especially if you decide you don't need the grunt of diesel -- just make sure you assess your needs carefully before making a decision.

Body Styles, Trim Levels, and Options

The 2500HD is available in regular, extended and crew cab body styles in both two- and four-wheel drive. Short or long boxes are available except on regular cabs, which are long boxes only. There are several levels: Work Truck, SL1, SLE1, SLE2 and SLT. True to their name, Work Trucks offer only the basics, but you still get manual dual-zone air conditioning, a 40/20/40-split bench seat and ABS. SL1 models come standard with a tilt steering wheel, cruise control, an AM/FM/CD stereo, driver message center and tinted glass. SLE1 models add power windows and door locks, remote keyless entry, power-heated exterior mirrors, foglamps and a leather-wrapped steering wheel. SLE2 models provide a six-way power driver seat and an upgraded Bose stereo. Top-of-the-line SLTs add leather bucket seats with heaters, driver-seat memory and dual 10-way power adjustments, automatic climate control, power-retractable mirrors and satellite steering wheel controls.

Powertrains and Performance

The HD's base engine is a 6.0-liter V8 rated at 300 horsepower and 360 pound-feet of torque. GMC offers two even more powerful options: an 8.1-liter V8 and the 6.6-liter Duramax turbodiesel. The 8.1-liter engine boasts an impressive 330 hp and 450 lb-ft of torque, while the Duramax diesel makes as much as 360 hp and 650 lb-ft of torque. The standard transmission for the 6.0-liter V8 is a five-speed manual with a four-speed automatic optional. The 8.1-liter V8 and Duramax diesel can be hooked up to either a six-speed manual or a heavy-duty Allison six-speed automatic. Being heavy-duty trucks, these brutes can certainly pull -- the maximum towing capacity of the 2500HD with the 6.0-liter engine is 10,500 pounds, while the 8.1-liter V8 can tow up to 12,000 pounds.

Safety

Four-wheel antilock disc brakes are standard. In frontal crash tests conducted by the National Highway Traffic Safety Administration, a Sierra earned a three-star rating (out of five) for driver protection and four stars for the front passenger. In the Insurance Institute for Highway Safety's frontal offset crash test, the Sierra was given an overall rating of "Marginal," the second lowest.

Interior Design and Special Features

Inside, Sierra buyers will find a logically laid-out interior with an easy-to-use dual-zone climate control system and clear, uncluttered gauges. Materials quality is unimpressive, and build quality, though improved over the last few years, is still behind the competition. The large cabin offers plenty of room and comfortable bucket seats.

Driving Impressions

The 2500HD is a reasonably comfortable truck for everyday use, but don't expect the plush ride of its light-duty siblings. Any of the available engines provide swift acceleration and ample towing power, but the Duramax diesel is probably the best choice for those who tow heavy loads. The manual transmissions are about what you would expect in a big truck, but the automatics shift smoothly and crisply no matter how heavy the load.