writer: Sean P. Holman
photographer: Courtesy of General Motors
General Motors needs you to like its new heavy-duty trucks. After all, they are one of the General's most profitable vehicles, and when you add the sales of Chevrolet and GMC together, they outsell the number one-selling Ford Super Duty. No matter how you slice it, the heavy-duty segment of the fullsize truck market still means big profits for struggling automakers, and despite rising fuel prices, they remain important vehicles. GM recently introduced the '07 Silverado and Sierra HD trucks, known internally as the GMT900, and invited us for our first drive of these important new vehicles.
We think the GMC is the better-looking of the two trucks, with its more refined lines.
The first thing you'll notice about the new trucks is the exterior, which matches that of its light-duty siblings, albeit with more muscular proportions. As with the light-duty trucks, we think the GMC Sierra HD is once again the looker of the pair, as the Chevy Silverado HD sports a set of ungainly, chromed jowls, which are about as attractive as Britney between rehabs. The 16- and 17-inch wheel-and-tire looks significantly undersized on these big trucks, and in a market where the competition starts out with 17-inch wheels and goes all the way up to 20s, 16s just don't seem to do it for us anymore. On a positive note, the bodies are extremely tight, and the fit of the panels and tightness of the gaps are among the tops in the automotive industry.
What's Hot: Bold new styling, comfortable interiors, increased fuel economy, best ride of the HD segment.
What's Not: No true F-450 competitor offered, uses upgraded GMT800 chassis, redesign didn't go far enough, offset steering wheel, low ground clearance.
As expected, the new HDs are available in three cab configurations (regular, extended, and crew), two bed lengths (6.5- and 8-foot), in single or dual rear wheels, and in two- or four-wheel drive. With the upgraded 2.5-inch receiver hitch, GM claims the best conventional tow rating of 13,000 pounds and a segment-leading GCWR of 18,500 pounds. With a fifth-wheel hitch, the tow rating improves to 16,700 pounds.
Inside the cabin, you'll find that the same high-quality materials and tight fit and finish found in the GMT900 LD trucks carries through to the HDs. Just as in the LD trucks, we prefer the "pure-pickup" dash to the "luxury-inspired" version shared with the SUVs, as it offers more storage, and gives you places to mount aftermarket accessories, such as radios, gauges, and switches. These interiors, even on the base models, are among the best available. However, we still noticed wind around the A-pillar and windshield header in a couple of our testers, something we have also noted in about half of the LD and SUV GMT900s we have sampled. So if you find wind noise distracting to your driving experience, drive before you buy.
Climbing underneath the big HDs reveals a modified GMT800 chassis that retains torsion bars, rather than switching to the LD GMT900's coilover shocks. GM cites increased durability for the reason to stick with torsion bars on the HDs, but unfortunately it stuck with the low hanging frame as well.
While the low frame height and ground clearance don't inspire spirited wheeling, at least the Z/71 off-road package is available on the HDs for the first time and includes skidplates, different suspension tuning, a high-capacity air cleaner, and a mechanically locking rear differential.
Two engines are offered on the HDs: The iron-block 6.0L Vortec V-8 with variable valve timing and putting out a class-leading 353 hp and 373 lb-ft of torque (for durability, the over 10,000-pound GVWR 3500HD dualie models have power output that is reduced to 312 hp) and the class-leading clean technology turbodiesel Duramax 6.6L V-8. We towed an 8,000-pound trailer with a 2500HD 4x4 equipped with the 6.0L and we think that even big-block die-hards will be impressed, especially with the economy that comes from being backed by an all-new wide ratio 6L90E six-speed automatic.