2019 GMC Sierra AT4 Sharp Turn for Off-Roading

OTAY MOUNTAIN WILDERNESS AREA, CA – So much for the hardships of off-roading.

The ’19 GMC Sierra AT4, a jacked-up and blinged-out version of the newly redesigned large pickup from General Motors, puts its passengers in the lap of luxury along the trail to redefine what it means to go off-piste.

It is the Gulfstream to the Cessna, luxury liner to fishing trawler, or cozy yurt to a leaky tent. You get the picture, which on the mountaintop here is a gloriously blue Southern California sky meeting a horizon of lush green Tecate cypress seen from the window of a leather-wrapped and climate-controlled interior. If this is what it means to go soft, play it as it lays.

This is not to suggest the Sierra AT4 lacks off-road credentials. Quite the opposite, it is designed as an off-road take on the pickup’s luxurious Denali trim. That means equal parts ruggedness and luxury with a sticker price approaching rarefied retail air.

GM, like rivals Ford and FCA US with its Ram brand, is taking every opportunity to cash in on the fat margins these trucks provide before fuel prices rise again and swing consumer preferences back to cars, or emissions regulations pull the curtain down on the party altogether.

Among a caravan of Sierra AT4s snaking up the trail here, the truck tackles the steep grade, its countless switchbacks and rutted terrain to the 3,566-ft. (1,087-m) summit without breaking a sweat.

The view from the summit easily explains why Californians are so passionate about their environment. Unique and sensitive plant varieties complement the cypress, and the area plays a critical role in San Diego’s multispecies conservation plan.

The terrain of Otay Mountain, just a 14-mile (20-km) drive from the city, is a jewel for outdoor enthusiasts, many of whom are equally passionate about their off-roading. According to the California State Parks, 16% of all national off-highway vehicle spending occurs in the state, or $20 billion of the $120 billion Americans dole out annually. California also has by far the highest percentage of OHV users in the country.

Unfortunately, the mountain’s precipitous canyon walls prevented stretching the legs of the AT4 with its optional 420-hp 6.2L gasoline V-8. The top-of-the-line GM light-pickup engine, a 2019 Wards 10 Best Engines winner, also features a new fuel-saving cylinder-deactivation system, stop-start technology and pairing with an all-new 10-speed automatic transmission.

We may have conserved a few drops of fuel compared with other V-8s on the market, but crawling up a mountainside does not offer the best opportunity to hyper-mile.

GMC Sierra AT4 off-road take on brand’s Denali luxury trim level.

However, the AT4’s 2-in. (51-mm) factory lift and Goodyear Wrangler Duratrac tires, along with the truck’s standard off-road-tuned Rancho monotube shock absorbers, were on full display. Clearance and grip are never in question, and the struts provide great control and feedback from the trail.

A standard Traction Select System allows us to pick at our discretion, depending on the terrain, the optimum drive mode, while a low-speed front camera comes in handy while negotiating tighter parts of the trail. The camera is helpful on an off-road track later in the day, too, providing vision at the crest of steep grades.

The off-road course with its natural obstacles and rock platform also provides a chance to lock the rear differential and put to work the 4-wheel-drive with its 2-speed transfer case. The transfer case includes low-range gearing for extreme conditions. Given the ease with which the AT4 tackles the course, it’s unclear how much work the transfer case performs, although the rear diff locks up nicely on several occasions.

Two other AT4 features are fun and helpful out on the trail. Several of the trucks are outfitted with a dealer-installed Kicker Bluetooth audio system, which is integrated into the MultiPro Tailgate standard on Sierra Denali, SLT and AT4 models.

The tailgate has six functions and positions to provide second-tier loading and load-stop solutions, a standing work station and a cutout to more easily access items in the box. But on this day, it provides a front-row seat overlooking the canyon to Mexico with a cold Gatorade and some Grateful Dead before jumping back in the AT4 for the trip down the mountain.

Hill Descent Control, which debuted on the previous generation of GM large pickups, also proves its mettle. Simply set the desired descent speed and the truck’s electronics will brake the AT4 in short bursts to individual wheels for a smooth, safe ride down the mountain. The driver only needs to steer. It is not something owners would use every day, but for weekend warriors it is a nifty safety backup.

The big trucks look good along the trail, too. Their ruby-red GMC badges contrast nicely against blacked-out grilles, and the brand’s signature C-shaped LED front lighting sparkle under the sun. Richly colored red, black and white exteriors with 18-in. machined aluminum wheels are stylish enough to catch the attention of a U.S. Navy Blackhawk helicopter, which swings in for a close-up while presumably conducting border patrol.

GMC Sierra AT4 upgrades include 2-in. factory lift, off-road-tuned shocks, skid plates.

For all its merits, though, the AT4 may not be the wisest choice for serious off-roaders.

For starters, it is a big truck that fills the width of the trail, so those canyon walls and precipitous drop-offs feel dangerously close at times. A smaller pickup from the GM stable, such as the Chevy Colorado ZR2, might be a better all-around choice.

The V-8 is not the most efficient in these conditions, either, although a less thirsty Duramax 3.0L inline 6-cyl. turbodiesel will be available in coming months. That engine should have plenty of appeal to AT4 customers.

But if the idea is to get to the trailhead before romping further into the bush with a pair of motorcycles, ATVs or a set of hiking boots, the Sierra AT4 provides plenty of cargo room for toys and gear. It also would be the perfect oasis after a day of kicking up dust.