What is the Sierra 2500HD?
The GMC Sierra 2500HD is, as the name implies, the heavy-duty version of the GMC Sierra 1500. GMC's offerings in the truck segment present as more luxurious alternatives to their Chevrolet Silverado cousins, though there's generally less variety in the GMC lineup compared to the Chevy equivalents. But GMC's own Denali sub-brand is proof enough that buyers are willing to spend big bucks on big trucks, and it's in the automaker's best interest to capitalize as much as possible.
To that end, GMC is launching a new model for the 2024 Sierra HD. It's called the AT4X, and it's aimed squarely at customers who want to do anything and go anywhere without sacrificing comfort. It doesn't look all too different from the standard 2500 models, but it has a (very) slightly different front fascia and AT4X badging to help it stand out.
Beyond the minor cosmetic changes is some new off-road ready hardware. The AT4X starts with a 1.5-inch lift for better ground clearance, an electronically controlled locking rear differential and 35-inch Goodyear Territory all-terrain tires. Other more detailed hardware changes include new upper and lower control arms for the front end, a larger steel skid plate to protect the transfer case and an aluminum skid plate at the front. That's all good, but the biggest news is the addition of Multimatic DSSV dampers, which replace the twin-tube Rancho shocks of the AT4. The advantage of DSSV dampers is, essentially, greater tuning variability to control damping. The result is more precision and better control both on- and off-road — and it's the same suspension setup used in the recently announced Silverado HD ZR2.
For those who want to take the HD AT4X to 11, there's the Extreme AEV edition. It further adds stamped steel bumpers and heavy-duty steel skid plates, plus the AEV's 18-inch Salta wheels (wrapped in the same Goodyear tires) and unique exterior badging.
The AT4X will be offered with gasoline and diesel engines. The former is a 6.6-liter gasoline V8 that makes 401 horsepower and 464 lb-ft of torque, while the turbocharged 6.6-liter V8 diesel makes 470 horsepower and 975 lb-ft of torque. Both engines are mated to a 10-speed Allison automatic transmission. Max conventional towing for the AT4X is rated at 18,500 pounds should you opt for the standard AT4X with the diesel engine. Gas-powered AT4X models can tow up to 16,000 pounds. Gooseneck trailering is rated at 18,000 pounds for the gas AT4X and 17,300 pounds for the diesel.
The cabin is exactly what we've come to expect from GMC: a slightly zhuzhed-up version of the Silverado's interior. There's an exclusive color scheme called Obsidian Rush and, as you might imagine, it's all blacked-out. It also includes massaging full-grain leather seats, a 12-speaker Bose sound system and wood decor. The dashboard is dominated by the 13.4-inch infotainment display we've seen in other Sierras and is partnered with a 12.3-inch customizable digital instrument cluster and 15-inch head-up display.