First introduced in 2019, the AT4 line is GMC’s offering to increasingly off-road-obsessed drivers. Loaded with the type of dependable, sturdy components that allow a vehicle to excel in off-road scenarios, the AT4 lineup transforms GMC’s already rugged trucks and SUVs into mud-throwing, rock-climbing adventure rigs. The experiment began with the 2019 version of GMC’s popular full-size pickup, the Sierra AT4, but has since expanded to include rugged off-road versions of the brand’s entire truck and SUV lineup. Now GMC is taking it one step further with an even more heavy-duty version of its marquee full-size pickup, the GMC Sierra AT4X.
The new version not only comes equipped with a full slate of high-end off-road features, like Multimatic DSSV dampers and front and rear electronic locking differentials, but is also one of the more luxurious trims that even gives the upper-tier Sierra 1500 Denali Ultimate a run for its money. Noteworthy interior features include heated and ventilated 16-way power front seats with massage, and while the AT4X also comes standard with a massive 6.2-liter V8 (which is an optional upgrade on the AT4), the easiest way to differentiate the two trims comes down to their off-road equipment. So how do the two off-road versions of the pickup stack up against each other in the battle of the 2022 GMC Sierra 1500 AT4 vs 2022 GMC Sierra 1500 AT4X?
The AT4X is obviously the better equipped of the two, but it also comes at a $12,500 premium over the AT4 model. Let’s take a closer look at the two pickup off-road upgrades and see if the new AT4X is worth the price.
If you were to choose one component that truly sets the two trims apart, it would have to be the AT4X’s shocks: Multimatic Dynamic Suspensions Spool Valve (DSSV) dampers. Shock absorption is important in any truck but especially pertinent when it comes to off-road models, which typically face much harsher road conditions than their on-road counterparts. With the Multimatic DSSV dampers, GMC has pulled out all the stops, equipping the AT4X with some of the most cutting-edge technology on the market in an effort to claim the off-road crown.
Since first bursting onto the scene on Chevy’s Colorado ZR2 in 2016, the Multimatic DSSV dampers have become the go-to shocks for the new breed of off-road pickups. These dampers represent a sea change in the world of shock absorption, throwing out a model that’s worked for well over 100 years in favor of some intriguing new technology that’s steadily revolutionizing the industry.
For those in need of a quick refresher: traditional shock absorbers, like the Rancho monotube shocks found on the AT4, are designed to have a piston force its way through a larger chamber filled with hydraulic fluid held under pressure. The piston features small apateurs through which this hydraulic fluid can flow, with a stack of shims controlling the rate of flow. As drivers navigate over bumps and fitches, these shocks take the brunt of the impact, resulting in 9.84 inches of front-wheel travel, 10.62 inches of rear-wheel travel, and a smoother, less jarring ride for all involved. The AT4’s Ranchos do this better than most but still rely on a concept first developed over a century ago to smooth out the kinks inherent to off-road fun.
When GMC set out to design its next-generation off-roader, Multimatic was likely one of the design team’s first calls. The Canada-based outfit has become an industry leader for components, systems, and engineering services in the automotive world, earning a solid reputation for quality and innovation that’s earned the company the distinction of being named one of Automotive News’ Top 100 Global OEM Parts Suppliers. From control arms to tailgates, Multimatic does it all, but it’s the company’s work on damper technology that’s really been the biggest boon to its reputation as of late.
In retrospect, Multimatic’s innovation was a relatively simple concept: take the spool valves that have been used in hydraulic systems for years and find a way to integrate them into automotive suspension dampers. Spool valves are built using spring-loaded valves, which can open and close at different rates as dictated by the speed of the damper’s shaft. The real innovation is the fact that these spool valves can be tuned for different applications depending on driving conditions. Drivers can access the damper’s Keyholes, tuning the system to light pressure to allow for a softer, smoother ride for on-road driving or adjusting it for heavy pressure, which provides a firmer, more resilient off-road experience. The result is a shock absorption system that is both position and velocity-sensitive, a rarity in the industry up until this point that’s best experienced from behind the wheel.
Velocity-sensitive dampers have been around for a while, but Multimatic’s design is still recognized as a game-changer for its ability to deliver consistent performance in a variety of conditions, as well as for the relative ease of tuning when compared to traditional piston-and-shim shocks. The DSSV dampers also hold up well to intense, prolonged use, thanks to the fact that the hydraulic fluid’s relative viscosity doesn’t have nearly as much of an effect on performance, meaning that as things start to heat up, your ride won’t suffer. The DSSV system saw its first deployment on the midsize Chevy Colorado, but Multimatic has scaled up the original design to up the off-road credentials of the 2022 Sierra 1500 AT4X.
The AT4 might not have Multimatic’s next-generation DSSV dampers, but it holds its own with a set of Rancho RS7MT shocks. While not as cutting-edge as the Multimatic system, the Rancho shocks still rank near the top of the heap when it comes to traditional monotube shocks. The components feature a two-inch monotube body filled with an all-weather hydraulic fluid that’s notable for its ability to withstand extreme temperatures: from as low as -40 degrees all the way up to 248 degrees Fahrenheit. This goes a long way in addressing the temperature-related performance issues mentioned above, giving the AT4 the ability to operate in a variety of conditions.
In addition to the temperature-resistant fluid, the Rancho shocks feature an internal rebound bumper, and shouldered rubber bushings go a long way in addressing the system’s noise and vibration, and PTFE-banded pistons have a marked improvement on ride comfort. The Rancho shocks lack the Keyhole system that makes the Multimatic setup so customizable but addresses the on vs off-road schism with Deflective Disc Valving. Designed with digressive, progressive, or linear tuning, this Deflective Disc Valving can be tweaked to respond to a wide variety of road conditions and driving styles.
Off-Road Chops: Ground Clearance
While the Multimatic DSSV dampers might get all the attention, they’re just one component in the Sierra 1500 off-road arsenal. Both off-road trims include four-wheel drive, GMC’s Hill Descent Control, skid plates, Goodyear Wrangler DuraTrac Mud-Terrain, recovery hooks, and a two-speed Autotrac transfer case. But the AT4X completes the build-out with a host of exclusive features that are well worth the higher price tag.
Let’s start with the pickup’s body itself. In the world of off-roading, trucks are often measured by their ground clearance, as well as their approach and departure angles. These latter two figures describe how steep of an off-road obstacle drivers can take on without having to worry about scraping up their front or rear bumper. Off-road-specific vehicles often feature an improved approach and departure angle over on-road models, and the two Sierra 1500 trims are no different.
The AT4X is offered with 11.1-inches of ground clearance, besting the AT4’s 10.8 by a small margin, but when it comes to approach and departure angle, the more affordable AT4 actually beats the higher-end trim. The AT4 has a 28.7-degree approach angle with the front chin spoiler removed and a 27.2-degree departure angle: both notably higher than the 25.5-degree approach and 23.9-inch departure on the AT4X. Given the AT4X’s height and vastly improved shock absorption technology, this is a trade-off most drivers will probably be able to live with, but it’s one area where the AT4 comes out on top.
Off-Road Chops: Differentials
When it comes to differentials, the AT4X is hard to beat, thanks to its first-in-class front and rear electronic-locking differentials. The feature can be engaged at any time so long as the AT4X is in Off-Road mode and makes navigating hills and pitted, uneven terrain easier than ever, thanks to improved traction. In basic terms, locking differentials allow the two halves of the front or rear axle to lock together, causing both wheels to rotate at the same speed. If one wheel starts to lose traction and spin uselessly, torque can be sent to the wheel with more traction, allowing drivers to navigate challenging terrain without taking an undue toll on their vehicle or the trail itself.
Locking rear differentials have long been popular among off-road D.I.Y.-ers looking to customize their 4x4s and have steadily made their way into the mainstream in recent years, with more and more trucks and SUVs being sold with locking rear differentials. Locking front differentials are another matter altogether. Used mainly for low-speed off-road endeavors such as rock crawling, front locking differentials are a rarity in a factory vehicle and aren’t even found on the new generation of so-called super trucks like the Ford Raptor or Ram 1500 TRX.
The scaled-down AT4 opts for an Eaton G80 locking rear differential in place of the AT4X’s front and rear-locking setup. The single locking differential might not offer the same level of performance but if you’re only going to have one locking differential on a 4×4 vehicle, choosing the rear is usually the way to go. The G80 design is noteworthy for its ability to automatically detect wheel slip and jump into action without any input from the driver: when the system detects a rear-wheel speed difference greater than 120 RPM, it jumps into action, locking the wheels together and resulting in a safer, seamless driving experience that will go a long way in improving any off-road journey.
Off-Road Chops: Driving Modes
Then there are the selectable driving modes. Both the AT4 and AT4X come standard with a two-speed Autotrac transfer case which allows drivers to choose between five options: Auto 4WD, 4HI, 4LO, 2HI, and Neutral. It’s a feature that’s sure to get a lot of use by serious off-roaders, but it’s the Sierra 1500’s selectable driving modes that really caught our attention this time around. The AT4 comes with four selectable driving modes, including Tour, Sport, Off-Road, and Tow/Haul. These modes have the ability to tweak throttle input, steering feel and transmission shifting strategy, which makes transforming the pickup from a highway hauler to an off-roader is as easy as pushing a button. Off-road mode is perfect for higher-speed off-road driving, ensuring enhanced traction and comfort no matter how fast you’re eating up the trail.
The AT4 ups the ante by adding a new Terrain mode that’s ideal for low-speed driving in challenging off-road conditions. It also allows for one-pedal driving where the Sierra takes over braking duties, allowing the driver to better concentrate on piloting the pickup through tricky off-road scenarios. Terrain mode is the ideal setup for rock-crawling or descending steep grades and provides a helpful little safety net that takes a lot of stress out of the off-road experience. It’s an approach reminiscent of GMC’s Hill Descent Control, which is also included on the AT4 and AT4X, though Terrain mode seems a little more of a flexible version.
It’s All a Matter of Preference
In comparing the AT4 and AT4X, it largely comes down to a matter of what drivers are looking for. The AT4X is undeniably well-equipped, with a full slate of first-in-its-class off-road technology that immediately vaults the pickup into the running for the best off-road models currently on offer, but it comes at a price. Sure, drivers will see a host of impressive equipment upgrades like the next-generation Multimatic DSSV damper and front and rear electronic-locking differentials – not to mention the AT4X’s luxuriously appointed interior – but for those seeking a lighter-duty off-road companion, the more affordable AT4 still checks all the boxes.
The AT4 model might not come with all of the bells and whistles as the new AT4X, but with significantly upgraded shocks and locking rear differentials, it’s still a marked improvement over the new generation of so-called “soft-roaders” that try to look the part with a host of aggressive styling updates but offer little in the way of actual off-road capability. No matter which version of the 2022 GMC Sierra 1500 you choose, you’re sure to enjoy your time behind the wheel exploring all the pitfalls and adventures that off-roading has to offer.