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2024 GMC Sierra HD AT4X: Luxury Off-Road Towing Monster, With Optional AEV Upfit

Tracking through the muddy footsteps of the Sierra 1500 and Canyon AT4X models, the Sierra HD AT4X stands taller than its trim mates and runs on 35-inch off-road friendly tires.
2024 GMC Sierra HD AT4X(Photo/GMC)
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Expected to hit dealers sometime in the fall, GMC will build a third AT4X trim-equipped truck, this time based on the heavy-duty Sierra. Just like the Sierra 1500 and Canyon, you get a lifted suspension, fancy shock absorbers, and proper off-road tires. But the Sierra HD breaks the mold by retaining its optional Duramax diesel power and mega towing capacity.

Sticking With the AT4X Recipe

2024 GMC Sierra HD AT4X
(Photo/GMC)

Just like the other AT4X models, GMC will lift the Sierra HD an additional 1.5 inches, as well as install Multimatic DSSV shock absorbers, a rear e-locking differential, 35-inch (LT305/70R18) Goodyear Wrangler Territory mud-terrain tires, beefed-up control arms and steering knuckles, and skid plates up front and for the transfer case.

And to make the best use of that equipment is Off-Road mode, a new driving mode that utilizes stability control systems as well as engine and transmission controls to improve driving feel when it’s time to leave the pavement.

2024 GMC Sierra HD AT4X
(Photo/GMC)

But think of this as more a glamping kind of truck, as opposed to pure camping, as the Sierra HD also includes luxury appointments like leather-wrapped massaging front seats. That will help you stay comfortable while listening to the 12-speaker Bose sound system. To add some old-school class, GMC added Vanta Ash wood to the trim, too.

Of course, no modern interior feels complete without a plethora of screens. In this latest AT4X, GMC installed a 13.4-inch center console touchscreen to control that Bose stereo, among many other things. Your instrument cluster is a fully digital 12.3-inch screen, with multiple information configurations to choose from. That’s complemented by a 15-inch head-up display to help keeps your eyes looking ahead.

2024 GMC Sierra HD AT4X
2024 GMC Sierra HD AT4X AEV; (photo/GMC)

Powered Up

Two engines will be offered in the 2024 GMC Sierra HD, both of them displacing 6.6 L. The standard V-8 runs on gasoline and produces a healthy 401 horsepower at 5,200 rpm and 464 pound-feet of torque at 4,000 rpm, respectively. 

But feel free to go big and tick the optional diesel-powered engine, which GMC calls Duramax. The turbocharged oil burner delivers 470 horsepower and a stump-yanking 975 pound-feet of torque. And, in the diesel, you reach torque peak at just 1,600 rpm.

Regardless of what fuel you put in the fuel tank, a 10-speed transmission sends power to a four-wheel-drive system. 

Tow as You Go

2024 GMC Sierra HD AT4X
(Photo/GMC)

Even with all of these off-roading chops, the Sierra HD AT4X can tow up to 18,500 pounds. Moreover, GMC added 14 different camera views to keep a close eye on things like the hitch, bed, and rear sides of the truck and trailer. GMC’s ProGrade trailering system is optionally available as well. That system adds several driving aids, such as trailer blind-spot alert and adaptive cruise control with trailering.

This particular trait helps the Sierra HD AT4X stand out. Often, off-roading credentials take away towing potential. And, indeed, the Sierra HD in other configurations towing peaks surpass 20,000 pounds. But, up to 18,500 pounds still far exceeds the vast majority of what most want to hitch up anyway — and certainly, when folks then head to the desert with that load.  

2024 GMC Sierra AT4X Extreme AEV Edition

2024 GMC Sierra HD AT4X
2024 GMC Sierra HD AT4X AEV; (photo/GMC)

And for those wishing to take it further, GMC once again teamed up with American Expedition Vehicles (AEV) to offer an upgrade package to the AT4X trim. The Extreme AEV Edition package adds to the Sierra HD AT4X stamped steel bumpers with integrated recovery points and front winch compatibility, additional steel skid plates, and 18-inch AEV Salta wheels. Of course, you also get unique badging both inside and out.

2024 GMC Sierra HD AT4X
2024 GMC Sierra HD AT4X AEV wheels; (photo/GMC)

Sierra AT4X First Impressions

The 2024 GMC Sierra AT4X definitely looks the part, with huge ground clearance and enough space to fit a tall cup of coffee on top of the tire without bumping the bottom of the wheel well. Simultaneously, the knobby tires with lots of sidewall add toughness and “take me off the beaten path” vibes. 

That said, this is a nearly 21-foot-long truck with more than 13 feet between the front and rear axles. Its inherent shape and size limit its true off-roading potential.

2024 GMC Sierra HD AT4X
GMC revealed the Sierra HD AT4X in front of journalists at the first drive event of the Colorado AT4X; (photo/Robin Warner)

The other hesitation is cost. GMC will announce pricing closer to the fall. But, considering the GMC Sierra 1500 AT4X starts at $83,545, you’re likely looking at nearly six figures just to get started in one. That rules it out of a lot of folks’ budgets.  

Then again, this combination of rugged outside, luxury inside, and towing it all behind you at the same time, may prove too attractive to ignore.

Just a Chevy Silverado HD ZR2 With Another Name?

Mechanically the GMC Sierra HD AT4X is the same as the Chevy Silverado HD ZR2. You get the same shocks, wheels, 35-inch M/T tires, suspension components, 11.6-inch ground clearance, and AEV upfit package option. Moreover, the GMC offers the same two 6.6L engines as Chevrolet, not to mention the 10-speed transmission and four-wheel-drive system. As a consequence, the two trucks also share the same towing specs. 

You see a lot of overlap inside as well, with the same size screens for the digital instrument cluster, center console touchscreen, and head-up display. But GMC also boasts having massaging front seats and Ash wood trim. And, just like the Canyon and Sierra 1500 AT4X models, the exterior and interior styling is distinct. Basically, the GMC has a classier interior, whereas the Chevy is a bit more sporty feeling inside.

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