GMC SIERRA AT4
I love automotive proving grounds. They’re a place where I can push the envelope of driving and evaluating a vehicle in a safe, spirited fashion. I’ve been to many over my years of testing new models, but not to the Eaton Proving Ground in Michigan.
GMC invited a group of truck testers to a 4WD swath of this 600-acre proving ground to put its newest pickup to the test over a course of dirt tracks, boulders, water crossings, and deep, silty mud. One of the highlights of the all-new 2019 Sierra 1500 AT4 is its Eaton rear locking differential.
Although the pickup shares some of the same mechanicals that can be found in the lineup of light-duty Sierra pickups, the AT4 trim level (AT4 stands for All-Terrain 4WD) has been designed and engineered to be the authentic off-roader in the GMC family. It’s differentiated by a number of add-ons and is available with a bigger engine.
On the outside is a large, tasteful black-and-chrome grille that touts GMC’s “professional grade” design. The truck sits 2 inches taller than its stablemates. Toughened and purposeful exterior elements include red tow hooks and 18- or 20-inch wheels that ride on off-road tires.
A two-speed transfer case and specially tuned Rancho monotube shocks validate its 4WD credibility. Standard issue is GMC’s MultiPro tailgate that can be configured in six different ways; a drop-down step allows easier access into the bed and a 120-volt power outlet adds practicality for outdoor activities and work duties. Available with the tailgate is an optional embedded Kicker sound system, and USB and AUX inputs.
The interior is upscale and fully tech-savvy, plus it’s been thoughtfully crafted with materials that will withstand backcountry duty, with dark leather appointments and extra-large protective floor mats. The five-passenger pickup comes in short- or standard-box configurations.
Two engine choices include a standard 5.3-liter V-8 with Dynamic Fuel Management that is mated to a six-speed automatic transmission, and a 6.2-liter V-8 with 420 horsepower and 460 lb.-ft. of torque matched to a 10-speed (a $2,500 option). It has a towing capacity of 9,400 pounds. An optional Performance package ($2,150) adds a cat-back performance exhaust and performance intake system, providing boosts of 15 horsepower and 9 lb.-ft. torque, which brought my test truck to a healthy 435/469, with pleasing, punchy torque and a delightful exhaust note.
The drive day included close to 200 miles of on-road evaluation and ample opportunity to motor more slowly and technically along off-road tracks and over backcountry obstacles. Notable was a comfortable pavement ride, with excellent steering response as a result of new steering tuning, and a compliant suspension.
Motoring on the 4WD tracks, I liked the manual mode for a smarter, personal gearing selection, hill-start assist, hill descent control, and the nearly 11 inches of ground clearance. My favorite takeaway was the AT4’s collection of cameras bundled in the Technology package that provide views in every direction, including a bird’s-eye view.
Onboard goodies are plentiful and bring GMC’s standard 4G LTE WiFi, accident avoidance systems, Bose audio system, integrated navigation system, wireless smartphone charging, an 8-inch gauge cluster display, heads-up display, and a customizable 15-inch diagonal display unit that shows the tilt and approach angles of the truck, along with other valuable off-road information.