First Look: 2024 GMC Sierra HD AT4X

Car companies are famous for mining every single shred of goodwill out of a popular trim or nameplate when they suddenly find themselves with a hit on their hands. Fortunately, when the bones are as good as this, the proliferation of models can be considered a Very Good Thing.

Enter the 2024 GMC Sierra HD AT4X. The overlords at General Motors have permitted their truck brand to delve into the corporate off-road parts bin and have a root around – paying particular attention to the magnificent Multimatic DSSV dampers which are the party pieces on top-tier variants of dirt-focused trucks from The General. For those not in the know, those suspension bits are the product of a Canadian company and feature technology hewn from lessons learned in the likes of professional desert racing and Formula 1. In short, they are a tremendous piece of kit.





Along with some of the segment’s best off-road suspension dampening, the AT4X adds a factory-installed 1.5-inch (38mm) suspension lift, then goes ahead and places specific control arms up front plus unique steering knuckles to appropriately handle that raised height. A rear e-locking differential is on board, plus skid plates in the form of a steel one over the transfer case and an aluminium one covering things up front. Those are 35-inch Goodyear Territory tires at each corner, if you’re wondering.

A choice of two engines are on tap, both familiar to GM fans. A 6.6L gasser is the standard mill, making 401 horsepower and 464 lb.-ft of torque. The one you really want is the 6.6L Duramax diesel, producing 470 ponies and a towering 975 lb.-ft of twist. It is this engine which, in our testing, has been shown to fit the personality of GM’s heavy-duty trucks to a tee. A 10-speed automatic handles shifting duties no matter which engine is selected. Towing prowess tops out at 18,500 pounds when properly equipped.



Walking up to these trucks in person gives one a sense of just how enormous they are, keeping in mind yer author is 6’6” in his size 13 stocking feet. The top of its hood is chest level, meaning even yours truly will need to step on the power running boards to scrape off the windshield on a cold December morning. Those 35-inch flotation size tires look ready to pummel the earth into submission, and it probably will since diesel-powered units will weigh well in excess of 8,000 pounds. And forget leaning in the driver’s door to grab something out of the deep centre console without hauling oneself into the cab. Ground clearance is a whopping 11.6 inches, up from about 10 inches in the standard truck, and height checks in at 82.6 inches. Check those clearance signs, folks.

Speaking of, the truck benefits from the same interior upgrades as other GMC HD pickups, which is to say it jumps leaps and bounds over the old one as if evolution went straight from protozoa to human beings. Soft-touch surfaces and luxurious appointments abound, clad in an Obsidian Rush colourway which is unique to the AT4X. The full-grain leather-wrapped front seats have a massaging function, meaning one can unwind and decompress with the same verve as those DSSV dampers working underneath the truck. The authentic Vanta Ash wood trim looks expensive (and, more importantly, real) while the 12-speaker Bose surround sound audio system is sure to crank out Prime Country with the best of them.



Most importantly, these HD pickups receive a 13.4-inch infotainment touchscreen, a tablet tasked with running major truck operations plus music and navigation. It is complemented by a 12.3-inch configurable gauge cluster ahead of the driver and a 15-inch-diagonal head-up display. In short, there are more screens in there than your local cinema. More cameras than the cineplex, too, with views ranging from the trick Transparent Trailer View to a Bed View with zoom. In fact, up to 14 different camera angles are available to help drivers keep an eye on the truck and their stuff.

If all that’s not enough for ya, GMC will be glad to point you in the direction of a Sierra HD AT4X AEV Edition. This brute takes everything on the AT4X and adds a yaffle of extra off-road tools. Up front is a robust stamped steel bumper with integrated recovery points and front winch capability, an addition which looks great and adds a ton of functionality but slightly harms approach angles compared to the AT4X (29.8 vs 31.6 degrees) since it juts out a bit further than the stock bumper. Choose your weapon wisely, then. There is another steel bumper out back, skid plates are swapped out for heavy duty steel units over the steering gear and transfer case, while the expected AEV badging pops up in conspicuous places around the truck. The AEV trim showed up when corporate cousins at Chevy tossed a set of ZR2 keys to AEV brass Dave Harriton and told him to outfit the thing as if he was headed into the wilderness. This truck is a continuation of that relationship.



With the addition of an AT4X trim, and its AEV counterpart, GMC has realized its multi-pronged approach of offering gonzo levels of off-road capability in each size class of its pickup truck portfolio. With this ability in midsize, full size, and heavy duty segments, the brand is – along with Chevrolet which offers similar kit on three sizes of ZR2 trucks – uniquely positioned to have a rig on tap for just about every off-road customer.

The 2024 GMC Sierra HD AT4X and the accompanying AEV Edition are expected to arrive at dealerships in this autumn.