GMC was known for its big-block grunt for many years, and people stayed away from the company's anemic diesels in droves. This all changed in 2001 with the introduction of the 6.6L Duramax turbodiesel, which was co-developed with Isuzu. With power wars between the HO Cummins and venerable Power Stroke heating up, the Duramax helped put GMC back in the race. After Dodge announced the Cummins 600, GMC quickly responded by upping the Duramax output.
GMC sent us its newest version of the Duramax, which now pumps out 310 hp and 590 lb-ft of torque, wrapped in an Onyx-Black 2500 HD Crew Cab SLT 4x4 backed by the coveted Allison five-speed automatic transmission. These options brought the GMC to an eye-popping $47,583 of hard-earned cash, or the equivalent of 1-1/2 years of an entry-level staff editor's salary. Fortunately, we had the benefit of XM radio and comfortable seats. Unfortunately, every tester bemoaned the GMC's bipolar ride. With an ultra-cushy front A-arm and torsion bar suspension and an overly harsh rear leaf suspension, the GMC bucked and pogo'd along the freeway, leaving some editors clamoring for the worker's comp form.
With or without the trailer, the GMC was always half a step behind the category leader. At the track, the Sierra pulled a competitive 8.99 0-60 run and a 16.93 quarter-mile at 81.34 mph. With substantial turbo lag, the Duramax felt somewhat lethargic down low, but once the turbo was spooled up, the Duramax pulled as hard as a freight train. Passing power on two-lane roads was exceptional. The brake feel was generally good but faded quickly, falling behind the Dodge and Ford in 60-0 unladed braking distances, scoring 154.37 feet.
Out on the highway, with trailer in tow, the GMC became a completely different machine. The suspension smoothed out and the ride became downright luxurious, exhibiting none of the harshness so apparent when it was unloaded. The GMC's chassis always felt stable and unflappable, and the comfortable, if not a little dated, cockpit was good for long distances. We commended the Sierra's steering, and the brakes felt confident and solid with the trailer attached.
Like the Dodge, the Duramax was also able to hit a top speed of 75 mph while running the grade, and the Allison transmission did a good job of holding the Sierra's speed to 55 mph while running downhill. The GMC's trailer mirrors extend at the touch of a button but create a fair amount of wind noise and don't have convex glass, so using them takes some getting used to.
If you plan on buying a truck for around town use, keep in mind that the competition has a leg up on the GMC in unladed comfort. The new power is a welcome addition to the Duramax, and with a large bed and comfortable interior, the Sierra was our pick for long distance hauls while loaded up. For those cross-country road trips, we would strongly suggest the XM option and the quality Bose system that is available.
From The Logbook:The turning radius is as wide as a whole city block.Senior Tech Editor, Bob Ryder
How can GM install such a small wheel and tire package on this truck? It looks like the HD is riding on spares.Associate Editor, Dan Ward
Wow, this thing actually rides great with the trailer attached - really comfortable.Associate Editor Sean P. Holman