- The 2024 GMC Sierra 2500HD AT4X and Extreme AEV Edition debut as the most off-road-capable models in the brand’s heavy-duty lineup.
- The AT4X boasts 35-inch mud-terrain tires, protective skid plates, and a jacked-up suspension with sophisticated spool-valve dampers.
- The Extreme AEV Edition’s add-ons come from aftermarket supplier AEV and include exclusive 18-inch wheels, stronger skid plates, and unique steel bumpers.
All work and no play makes Jack a dull boy. That is unless Jack drives a 2024 GMC Sierra 2500HD AT4X or an Extreme AEV Edition, which together debut as the most off-road-focused models in the brand’s heavy-duty lineup. Able to tow up to 18,500 pounds and haul a payload of up to nearly 3300 pounds, the new AT4X and its AEV-enhanced counterpart are as capable as most other three-quarter-ton Sierras, but they also come with the necessary equipment to warrant some added fun when the workday is done.
An Off-Road Semi Truck
While the 2024 model year marks the first time GMC’s AT4X badge has appeared on a Sierra HD, the dirt-oriented model was introduced on the 2022 Sierra 1500. Previously, the heavy-duty pickup truck’s top off-road option was the regular AT4, which is offered on both the 2500HD and 3500HD. The new AT4X is only available on the 2500HD configured with the crew-cab body style and the standard-length cargo bed.
The Sierra 2500HD AT4X is outfitted similar to the recently revealed 2024 Chevy Silverado 2500HD ZR2. Both feature black 18-inch wheels wrapped with chunky 35-inch Goodyear Wrangler Territory M/T tires. The AT4X’s suspension is raised 1.5 inches, and the truck is buoyed by sophisticated Multimatic DSSV spool-valve dampers. Also found on professional race cars and trucks, these fancy shocks feature three separate spool valves that better help on-road composure and withstand off-road abuse.
Other bits exclusive to the 2024 Sierra 2500HD AT4X include a revised front suspension with enhanced steering knuckles as well as unique upper and lower control arms. The bottom of the truck is also better protected from taking a beating thanks to the addition of an aluminum front bash plate and a larger steel skid plate for the transfer case. An electronically locking rear differential is part of the AT4X kit too, as is an Off-Road drive mode to help tackle tough obstacles.
While four-wheel drive and an Allison 10-speed automatic transmission are mandatory, customers can choose between two powertrains: the standard 401-hp gas-fed 6.6-liter V-8 or the optional Duramax diesel 6.6-liter V-8, which makes 470 horsepower and an impressive 975 pound-feet of torque.
An Extra Extreme AT4X
What the AT4X and lesser heavy-duty Sierras don’t have is hardcore hardware that can only be found on the formidably named Extreme AEV Edition. With exclusive parts from aftermarket supplier AEV, it’s basically a further fortified version of the AT4X. The more extreme off-roader comes with steel-stamped front and rear bumpers that feature a winch accommodation and recovery points. Tougher underbody armor and a set of AEV-specific gloss-black 18-inch wheels complete the deal.
There are some minor technical differences between the AT4X and the Extreme AEV Edition. Both versions have an identical 25.7 degree departure angle, and their ground clearance is virtually the same at 11.6—11.7 inches. However, the AEV has a slightly steeper breakover angle of 22.6 degrees (versus 21.2 degrees). On the other hand, the AT4X has a steeper approach angle (31.6 versus 29.8 degrees). The AEV add-ons also make it heavier, with GMC claiming the gas-fed version weighs 378 pounds more and the oil-burning one weighs 368 pounds more.
With GMC giving the 2024 Sierra HD lineup a host of updates, including refreshed styling and a snazzier interior, the AT4X and Extreme AEV Edition reap the benefits. They also come with desirable content such as a 12.3-inch digital gauge cluster, a 13.4-inch center touchscreen, and a head-up display. Every model also has legitimate luxury features such as genuine wood interior trim, leather upholstery, massaging front seats, and a 12-speaker Bose sound system.
The 2024 GMC Sierra 2500HD AT4X and the Extreme AEV Edition will start production sometime this fall. GMC hasn’t said how much either version will cost, but we expect a base price around $90K, with possibly an $8000 surcharge for the AEV-enhanced model.
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Senior Editor
Eric Stafford’s automobile addiction began before he could walk, and it has fueled his passion to write news, reviews, and more for Car and Driver since 2016. His aspiration growing up was to become a millionaire with a Jay Leno–like car collection. Apparently, getting rich is harder than social-media influencers make it seem, so he avoided financial success entirely to become an automotive journalist and drive new cars for a living. After earning a degree at Central Michigan University and working at a daily newspaper, the years of basically burning money on failed project cars and lemon-flavored jalopies finally paid off when Car and Driver hired him. His garage currently includes a 2010 Acura RDX, a manual ’97 Chevy Camaro Z/28, and a ’90 Honda CRX Si.