2024 GMC Sierra 2500HD AT4X AEV Review: A Burly Beast of Burden

A giant-sized truck that can take on all sorts of terrain — so long as the trail isn’t too narrow.

Published November 16, 2023

Heavy duty pickup trucks and the American West go together like peanut butter and chocolate. HD rigs are giant-sized and super-capable, made for towing horse trailers and farm equipment and camping trailers up and down mountains and over all sorts of the rough terrain that makes up the national forests and BLM land spanning mile after mile. Sure, all pickups feel at home out West — but in my experience, the bigger the rig, the better the fit.

So when GMC wanted to show off the latest additions to their premium off-roader AT4X AEV lineup — the Canyon AT4X AEV, the now-with-diesel-power version of the Sierra 1500 AT4X AEV, and the new Sierra 2500 AT4X AEV — it wasn’t too surprising the brand hauled a planeload of journalists out to Montana to do so. But while we had a chance to log a hundred-plus miles on all sorts of surfaces — highways, byways, dirt roads and off-road — in the Canyons, our time with the Sierra 2500 AEV was limited to a 30-minute drive loop along trails carved into a Big Sky country ranch.

Which, in full disclosure, left me feeling a little disappointed. As an admitted fan of HD pickups — partly because they still drive like trucks of yore, partly because of their insane all-around capability, and partly because I get a kick out of any passenger vehicle my six-foot-four frame has to climb up into — I’d been looking forward to logging some serious miles in the 2500 HD to see how it compares to the Ford F-250 Super Duty Tremor and Ram 2500 HD Rebel I’ve driven before.

So with that in mind, consider this a first drive review with an asterisk: I can’t actually tell you what it’s like to drive this vehicle on the road, where most copies are destined to spend most of their time. Once GMC hooks me up with one on my home turf, though, I’ll be sure to update this with more insights … assuming first that I can find a place to park it in New York City.

2024 GMC Sierra 2500 HD AT4X AEV: What We Think

The largest and fanciest off-road-oriented pickup truck in the GM portfolio — beating out the mechanically-almost-identical Chevy Silverado 2500 HD ZR2 Bison by a couple bucks and the more premium GMC badge — the Sierra 2500 HD AT4X AEV Edition delivers a ton of power and potential (and several tons of everything else). Its massive width and long wheelbase may hold it back on narrow trails, but so long as there’s enough space around it to maneuver, it should tackle just about any terrain you think it can handle — and in plenty of comfort, too.

To learn more about our testing methodology and how we evaluate products, head here.

The Sierra 2500HD AT4X AEV is really, really big

Like many segments of the automotive world today, the pickup truck market has seen some serious inflation — not just in prices, but in size, too. Today’s midsize pickups are the size of half-tons of two decades ago, while modern full-sizers rival heavy duty pickups from not long ago.

The 2500 HD AT4X AEV — available solely in crew-cab short-bed form — stretches 20 feet, 11 inches from stem to stern, 6 feet 10 inches from ground to crown, and 8 feet 9 inches from side to side, including the mirrors. Much of that space being filled with high-strength steel and other heavy materials as it is, this truck fully puts the heavy in heavy duty; the gas-powered version weighs in at 7894 pounds, while the diesel tips the scales at 8,605.

Of course, those specs in turn help enable some of the other remarkable figures associated with this mighty rig: for example, a towing capacity of up to 9.25 tons, and a payload capacity of 2,701–2,912 pounds, depending on specs. In other words, you can tow a full-grown elephant, or fill all five seats with T.J. Watt clones and put five more in the bed with capability to spare.

Its off-road capabilities impress, so long as you have space to use them

Speaking of specs, try these on for size: 11.7 inches of ground clearance, a breakover angle of 22.6 degrees, a departure angle of 22.7 degrees and an approach angle of 29.6. Those might not be able to match, say, a Ford Bronco Raptor, but as I found during my stint driving over Cretaceous-era rocks, they’re good enough for guv’ment work — and with the AEV Package, there are plenty of boron steel contact plates to shield sensitive bits against undesired-but-inevitable contact with the hard ground.

My tester had the 6.6-liter Duramax turbodiesel V8, which makes an impressive 470 horses and a monumental 975 lb-ft of torque. It’s the latter figure — and the advantages of turbocharging that make it less affected by altitude — that will likely make it the pick of the litter for the many HD buyers who plan on towing heavy loads, especially around the high altitudes often found between Colorado and California.

On the trails in Montana, the turbodiesel proved effortlessly capable, puttering all 4.6 tons of truck and occupants around the grounds with the greatest of ease. If anything, it almost felt like a liability; with the transfer case in low range and the 10-speed in first gear, it was almost impossible to be as smooth on the throttle as I’d have liked, with the torque rushing on aggressively as the turbo spooled up at 1,100 rpm or so. I found myself hopping back and forth between pedals more than usual when off-roading in order to maintain absolute control.

In all honesty, if I were planning on using my heavy duty Sierra as an overlanding rig, I’d be tempted by the gas-powered 6.6-liter motor. The gasoline V8 makes “just” 401 horses and “only” 464 lb-ft, but its naturally aspirated power delivery likely makes it a better fit for off-roading, where earth-rattling torque is less important than careful control. (Going gas also saves you nearly $10,000, should you be counting your pennies — enough to offset the whole cost of the AEV Edition package.)

It’s still rather civilized for a giant rig

obsidian rush interior of the 2024 gmc sierra 2500 at4x aev edition

Once you free solo your way inside, you’ll find the Sierra 2500 HD AT4X interior to be comfortable and (extraordinarily) capacious. The black-on-black — sorry, “Obsidian Rush” — colorway is perhaps a bit dour, at least compared to the fancy black-and-white-and-red-all-over guts of the Canyon AT4X, but that also means it should show less evidence of wear n’ tear over thousands upon thousands of miles. (Remember, kids, heavy duty pickups tend to be among the longest-lasting rides on the road.)

With more than 40 inches of headroom and legroom and more than 60 inches of hip and shoulder space in every seat, anyone smaller than Andre the Giant will have nothing to complain about space-wise. The rear bench, though, remains coach-class seating next to the front buckets; the driver and shotgun rider not only benefit from far better bolsters and cushioning, they even score heating, ventilation and massage features.

Like most of GMC’s trucks nowadays, the heavy duty AT4X boasts a crisp, fast-responding Google-based infotainment system — here, a 13.4-inch touchscreen, complete with built-in Google Maps. But if you’re working in cold weather and clambering in and out of the cabin often, you’ll probably appreciate that all the important controls — climate, volume, driving controls — all still use real buttons, all the way down to the delightfully old-school column shift lever.

Not that you’d expect any less in terms of features and capability for a pickup truck that can easily cross into six-figure pricing, of course. Shocking as it may seem, the AEV package pushes GMC’s 2500 HD up to around $95,000 after destination fee.

Based on my experience so far, I’d say the 1500 AT4X AEV remains the better choice for most people who don’t intend on towing four-plus-ton loads through the Rockies or need a six-foot-plus long bed in their off-roader: it’s a bit easier to drive while still delivering more than ample capability. Still, that truck starts at $90,935 … so hey, maybe it’s worth thinking extra-hard about how much you really will be towing and hauling to see if the heavy duty version is a better pick.