If you’re familiar with GMC, you’re likely familiar with their AT4 series of off-road vehicles.It wasn’t too long ago when the sub-brand was enhanced by the AT4X line, mixing enhanced overlanding capabilities with premium appointments akin to their luxurious Denali line. Now the AT4X badging has found its way, for the first time, onto the Sierra HD.
The 2024 GMC Sierra HD AT4X may ride the precipice of being a mouthful to say, but the idea behind it is rather simple: Premium off-roading with heavy duty capabilities. And that’s exactly what it promises.
Starting with the powertrain, it’s driven by a standard 6.6-liter gas engine, capable of 401 horsepower and 464 lb-ft of torque. For a turbocharged bump, there’s an optional 6.6-liter Duramax Turbo-Diesel, enhanced for 2024 and serving up 470 horsepower and an impressive 975 lb-ft of torque. Either is sent to an Allison 10-speed automatic.
And what’s a truck without payload and trailering? Starting with the HD AT4X gas, it can haul a max payload of 3,291 lbs and conventionally tow up to 16,000 lbs; a fifth-wheel/Gooseneck will bump that up to 18,000. The diesel variant can payload a little less at 3,068 lbs, but trailer more at 18,500 lbs conventional; though, fifth-wheel is down to 17,300 lbs.
So, the “heavy duty” is certainly still applicable, but where does the AT4 part fit in? For starters, a factory-installed 1.5-inch lift and Multimatic DSSV dampers, making contact to the ground through 35-inch Goodyear Territory tires wrapping 18-inch aluminum wheels. There are also specific front upper and lower control arms and specific steering knuckles. With 11.6-inches of ground clearance, the approach angle rides at 31.6 degrees, departure at 25.7 and breakover at 21.2. And as you can judge by the photos yourself, the HD AT4X is certainly off-road in appearance.
A new Off-Road Mode, when engaged, optimizes the trail-conquering experience by adjusting the anti-lock brakes, traction control and stability control. Throttle progression and shifting is also adjusted for better performance in those conditions.
Right, so the “AT4” part is covered, too; but, what about the “X?” Well, as expected, premium appointments are bountiful in the HD AT4X’s cabin. It starts with a unique Obsidian Ruch interior with authentic Vanta Ash wood trimmings. The seats are massaging for a relaxing cruise back from your hike, and the sound system fills the cabin via 12-speakers, courtesy of Bose. Screen real estate consists of a tablet-style 13.4-inch infotainment screen, a 12.3-inch driver information center and a 15-inch head-up unit.
Alright, so hopefully now all the pieces comprising “GMC Sierra HD AT4X” have clicked. We’ve painted the picture of an off-road-ready pickup with a bit of a softside; but, what if we were to tack on another acronym?
We spoiled it in the title: AEV, or “American Expedition Vehicles.” They’re well-known for taking serious off-road rides and pushing them even further with various bits of aftermarket support. And in the case of our HD AT4X, the AEV throws some serious material at it. It starts off with stamped steel bumpers with integrated recovery points and front winch capabilities. Underneath are steel skid plates protecting more components, including the steering gear and transfer case. The wheels are unique– 18-inch Salta wheels– as is the expected assortment of badging. Inside, expect some AEV-logos and floor liners.
The AEV treatment does change some key numbers; though, the gas and diesel performance figures are the same until it gets to payload and towing. The gas AEV Edition can payload 2,912 lbs, down slightly. It can tow the same 16,000 lbs conventionally, but fifth-wheel towing drops to 16,200 lbs. As for the diesel, payload is down to 2,701 lbs, conventional towing barely down at 18,4000 lbs and fifth-wheel towing decreased to 14,800 lbs. The AEV stands slightly taller at 11.7-inches of ground clearance, meeting obstacles with a 29.8 degree approach angle and leaving them with the same 25.7 degrees of departure. Breakover is up to 22.6 degrees.
And there we have it. The 2024 GMC Sierra HD AT4X and the AEV Edition will arrive in dealerships in the fall of 2023. No word on pricing yet, but we expect to learn that as we get closer to launch.
Keyword: GMC’s AT4X Treatment Spreads to Sierra HD; Joined by AEV Edition