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Second look: 2019 GMC Sierra AT4

by Byron Hurd

We get GMC's new all-terrain model dirty.

A few months back, General Motors invited us to Newfoundland, Canada, to drive the 2019 GMC Sierra 1500. Our time there was devoted pretty much exclusively to the range-topping Sierra Denali, though we did get a chance to sort of wander into a grassy field in the off-road-ready AT4.

GMC had more lofty ambitions for our off-pavement excursion, but unfortunately the course scouted out in advance was no longer suitable for any sort of rugged evaluation. To remedy that, GMC invited us to Michigan for a morning of trail driving at powertrain supplier Eaton's proving grounds outside the small but historic town of Marshall.

AT4

With AT4, you get a two-inch lift, standard four-wheel-drive with a two-speed transfer case and electronic locking rear differential (courtesy of Eaton, appropriately), Rancho monotube shocks, 18-inch wheels with Goodyear all-terrain tires, hill descent control and traction select. AT4 is also one of just two trims of the 2019 Sierra on which the new CarbonPro box is available (the other is Denali) and benefits from an integrated dual exhaust that adds a little more potency to the available 5.3L or 6.2L V8s.

More broadly speaking, AT4 is GMC's effort to give its off-road package a more coherent identity. Various GMC models have been sold in "All Terrain" trim, a naming convention which the company is currently retiring. It's a good thing, too, because the alternative might be the introduction of a 2020 GMC Terrain All Terrain. Yo dawg.

While the off-road suspension is available on other Sierra models (save for the aforementioned Denali, which has an adaptive suspension), AT4 is the place where the X31 package (GMC's variant of the Z71 suspension) really gets to shine.

On the road

Asphalt driving was hardly the point of our excursion, but we had to get to Eaton's facility somehow, and that meant knocking out a roughly 90-minute highway drive. At low speeds, the Goodyears make enough noise that you'd notice them, but it's lost to the general hiss of the pavement above maybe 25 miles per hour.

At cruise, the AT4 does just fine. The heartier suspension and aggressive tires don't seem to have much impact on its highway manners. Get on the throttle a bit and you'll hear the dual exhaust in action--a generally pleasant addition to the experience, especially combined with the thrust of our 6.2L test model.

Our example was also loaded up with the AT4 Preferred package, which allows the more rugged model to do a decent impression of the more refined Denali. The wireless phone charger came in handy on our return trip, letting us juice up our phones on our way back to the airport.

In the dirt

We arrived at Eaton to find the ground crusted over from seasonally crisp Michigan weather. The superficial frost did nothing to inhibit our progress around the off-road test course, and we got to experience everything from foot-deep puddles to foot-deep mud, along with some winding forest trails and a simulated boulder crawl just for giggles.

The course presented nothing that the Sierra AT4 couldn't handle, but some of the more challenging sections could cause trouble if approached without the appropriate caution. A set of ruts designed to show off the AT4's articulation had the appropriate course delineated by cones lest anybody get any funny ideas about taking them dead-on--a choice which would have done our test trucks' front ends no favors.

The mud section, while still controlled, was far less forgiving. A flagrant disregard for momentum left more than one driver in need of a tow-out. Michigan mud is not to be taken lightly.

Leftlane's bottom line

The 2019 GMC Sierra 1500 AT4 is new in name only, following in the footsteps of the last-generation Sierra All Terrain X. That's no bad thing, though, as the general off-road capability of properly equipped half-ton trucks was never really in question. Sierra is a premium truck, and its buyers are more likely to utilize the AT4's off-road chops to reach snowed-in hunting cabins rather than remote job sites, but in either case, it's more than up to the task.

2019 GMC Sierra 1500 Crew Cab AT4 base price, $53,200; As tested, $62,615

6.2L V8, $2,495; Technology package, $1,875; AT4 Preferred package, $1,420; Driver Alert 1, $890; Driver Alert II, $745; Red Quartz paint, $495; Destination, $1,495

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