2012 GMC Sierra 1500 SLE All Terrain Road Test and Review

by Benjamin Hunting

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December 5, 2011

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8 min. Reading Time

The 2012 GMC Sierra 1500 SLE All Terrain is the off-road flagship of GMC's full-size pickup truck lineup. Although it bears a similar name to the All Terrain HD Concept behemoth that has made the show circuit rounds, the GMC Sierra 1500 SLE All Terrain is a genuine working truck that has been given a healthy dose of 4x4 performance without compromising its drivability on pavement. The Sierra is a very serious pickup, and it has a lot to offer buyers whether they are looking for a task-focused tool, a comfortable daily driver, or a weekend warrior capable of shredding a trail without breaking a sweat.

2012 GMC Sierra 1500 SLE All Terrain: Competition

It's no secret that the full-size pickup segment is one of the most hotly contested areas of the American market. Pickups lead the list of best-selling vehicles in the country year after year, and full-size trucks in particular have been adopted by a wide range of different demographics - from families to contractors - who appreciate their interior room, hauling and towing capacity and rugged styling.

Perhaps the 2012 GMC Sierra 1500 SLE All Terrain's closest competitor would be its own corporate sibling, the Chevrolet Silverado 1500, which can be had with the same Z71 Off-Road package that is part and parcel of the All Terrain's equipment list. The Ford F-150 Raptor is another, more hardcore truck that aims to score points with the trail-driving, desert-running crowd, while the Toyota Tundra can be had with a TRD Off-Road package that offers upgrades similar to those provided on the Sierra All Terrain. For those considering an older truck design the Nissan Titan PRO-4X is available, although its lack of sophistication compared to more modern pickups leaves it lagging behind the other vehicles on this list. The Dodge Ram offers a number of off-road upgrade options but doesn't feature a specific trim level or package oriented towards trail-breaking.

2012 GMC Sierra 1500 All Terrain: Pricing and Trim Levels

The 2012 GMC Sierra SLE 1500 comes in the full rainbow of trim levels and packages that full-size truck buyers expect. We won't go into detail about the myriad of configurations that the Sierra 1500 can be ordered in - or the associated pricing with each edition - but we will tell you that the pickup can be had in regular, extended and crew cab body styles and that it offers bed lengths of between five-feet, eight-inches and a full eight feet. The 2012 GMC Sierra regular cab starts at an MSRP of $20,940, but this price can swell to above $50,000 depending on which options, trim and drivetrain selections are made.

The 2012 GMC Sierra 1500 SLE All Terrain model that joined our stable for a full week of testing was a four-door crew cab model that stickered for just under $43,000.

2012 GMC Sierra 1500 SLE All Terrain: Exterior

The 2012 GMC Sierra 1500 SLE All Terrain differs visually from standard crew cab editions of the Sierra in a number of ways. The vehicle gains a monochromatic grille and bumper that is keyed to the truck's color scheme (in our case, a very attractive black), fog lights mounted in the front bumper, Z71 badging on the rear fender (in order to denote the vehicle's suspension spec) and in the case of our tester truck 20-inch chrome rims. The GMC Sierra's overall styling takes a page out of the blocky, muscular playbook that has largely taken over the full-size truck market. Slab sides and an upright shape define the GMC's overall profile, while gentle curves on the pickup's hood and fender arches soften up the truck's utilitarian appearance and civilize it for duty outside of a worksite. All Terrain badges adorned the front fenders of the truck, and the vehicle also came with very useful power folding mirrors which add peace of mind when negotiating tight downtown parking spots.

The GMC Sierra 1500 crew cab model is exclusively available with the smallest cargo bed on offer, one that measures five-feet, eight-inches in length. The shortness of the SLE All Terrain's truck bed somewhat compromised its utility during our week with the vehicle. The 4x8 drywall that we picked up from Home Depot had to be leaned against the closed tailgate, protruding out the back and forcing us to be careful around corners so as not to slide it over the side. The short bed is a necessity, however, as combining the crew cab's additional passenger space with a longer cargo area would undoubtedly make the pickup too unwieldy in an urban setting. The truck's tailgate was easy to open and close, and a full bedliner protected the bed floor, sides and cargo rails from scratching or other damage.

2012 GMC Sierra 1500 All Terrain: Interior

There are a number of words that could be used to describe the passenger compartment of the 2012 GMC Sierra 1500 SLE All Terrain crew cab: vast, expansive and cavernous all immediately come to mind. Simply put, regardless of where one sits inside the All Terrain crew cab - up front in the dual buckets or out back on the three-person bench - there is plenty of personal space to go around. In fact, we found ourselves hanging out inside the truck's cabin after pulling into a parking spot on more than one occasion to continue our group conversations instead of braving the colder weather outside. The Sierra is so spacious that it almost feels like a small living room on wheels.

The seats themselves are wrapped in an easy-to-clean fabric that breathes well, and although the front cushions didn't provide as much support as we would have liked on longer trips, they hold both driver and passenger in place quite well through the corners. The rear seats generated no complaints, and the flip-up functionality that allowed the 60/40 split bench to fold against the rear wall of the cabin in seconds was extremely useful. Boxes of books and other fairly bulky items were ferried from point A to point B safely protected from the rain thanks to this practical feature.

The fit and finish of the 2012 GMC Sierra 1500 SLE All Terrain struck a good balance between functional and being easy on the eyes. Brushed metal accents adorned the dash, and several passengers were surprised by how upscale the plastics that formed much of the rest of the cabin looked. GMC aims to be a cut above its Chevrolet stable mate in terms of overall refinement and features availability, and the SLE All Terrain's standard dual automatic climate control, special gauge package and enormous center console offered subtle but effective up-market cues. The steering wheel featured controls for both the stereo system and cruise speed, and our truck also had an optional Bose speaker system, a moonroof, a power sliding rear window, power adjustable pedals and power seats to round out its list of interior equipment.

2012 GMC Sierra 1500 SLE All Terrain: Powertrain and Fuel Economy

The 2012 GMC Sierra 1500 SLE makes use of a 4.8-liter V-8 as its entry-level engine. This unit is good for 302 horsepower and 305 lb-ft of torque, and its fuel economy is rated at 14-mpg city and 19-mpg highway. It is also possible to order the Sierra with a 403 horsepower, 6.2-liter V-8, a 332 horsepower 6.0-liter V-8 and a 195 horsepower, 4.3-liter V-6. A mix of four-speed automatic and six-speed automatic transmissions handle the gear shifting duties for these motors.

Our SLE All Terrain featured a 326 horsepower, 5.3-liter V-8 that also generates 348 lb-ft of torque. A six-speed automatic is the only gearbox available with this engine, and fuel mileage for the unit checks in at 15-mpg city and 21-mpg highway for trucks equipped with automatic four-wheel drive (like the one we were driving). We saw just under 10 miles per gallon during our mix of stop and go and off-road driving in our time with the Sierra SLE. The factory ratings are likely possible if a light foot is used, but this is a big truck with an eight-cylinder engine, which means drivers should budget for fuel accordingly.

2012 GMC Sierra 1500 SLE All Terrain: Driving Impressions

The 2012 GMC Sierra 1500 SLE All Terrain bridges two distinct worlds: daily on-pavement cruising and hauling and the exciting world of off-road adventure. Although Montreal's truly deplorable road conditions can sometimes make it seem as though one is driving on the surface of the moon, we felt it wouldn't be fair to let the SLE All Terrain leave our hands without first putting its four-wheel drive system and trick suspension to the test in the environment in which the truck was intended to thrive.

A solid afternoon on our closed off-road test course revealed that the Sierra All Terrain is virtually unstoppable when the going gets rough. Neither standing water nor deep mud did so much as to slow the Sierra's forward momentum on the trail, and the truck's ride height advantage served it well when climbing over trenches and ruts. We experimented with the "automatic" four-wheel drive feature, which engages the front wheels when the rear tires start to spin, as well as four-wheel high and four-wheel low modes. All performed admirably well, and left us scratching our heads as to where we would have to go to find a landscape that would pose a legitimate challenge to the full-size truck.

Perhaps it should be come as no surprise that the All Terrain package is such a formidable back country chariot. It includes GMC's Z71 off-road suspension, Rancho extended-travel shocks, an Eaton automatic locking rear differential and tires that feature an aggressive tread pattern designed to hold on tight when things get slippery. Underneath the truck, skid plates make sure that all of the important bits are kept safe from any accidental encounters with immovable objects. In fact, the only aspect of the Sierra SLE that held us back on the trail were the optional running boards. While they did make it easier to climb in and out of the truck's passenger compartment, they also hung off the side to the degree that we were forced to pay attention to their positioning or risk snagging them on uneven ground. If you plan to play in the mud with the Sierra, then it's probably a good idea to forgo this feature.

Leaving the wilderness behind also proved to be no problem for the 2012 GMC Sierra 1500 SLE All Terrain. Although the more aggressive shocks and springs found on the truck did occasionally cause the rear end to step out slightly when turning around a bumpy corner, in general the truck was very comfortable and composed. It was also a quiet ride (another GMC specialty), with only the roar of the V-8 breaking the silence in the cabin during passing maneuvers. Steering was precise at all speeds, and braking was exemplary. The long wheelbase might pose a challenge for anyone not used to piloting a full-size pickup, but parallel parking was greatly assisted by the vehicle's parking sonar features. We were able to squeeze the Sierra in and out of seemingly tiny street-side spaces with relative ease.

Although we did not get a chance to put the Sierra's tow rating of 10,700 lbs to the test, the truck did offer plenty of power and impressive stability in all other driving situations, leaving us with little doubt that it would be able to hold its own as a tow rig. Our truck also came with an integrated trailer brake controller, a tow / haul mode for the transmission and the ability to manually select each gear for handling steep grades or tricky traction conditions.

2012 GMC Sierra 1500 SLE All Terrain: Safety

The 2012 GMC Sierra 1500 SLE All Terrain features six airbags - dual forward units, seat-mounted side airbags for driver and front passenger, and side curtain airbags that protect riders both front and rear. The truck also comes with a complimentary OnStar subscription, which can put truck owners in touch with first responders and other emergency personnel in just seconds, as well as StabiliTrak electronic stability and traction control. The automatic four-wheel drive feature is also handy for anyone who lives in the snow belt, as it can intervene when the road unexpectedly turns slippery and provide additional security and safety.

2012 GMC Sierra 1500 SLE All Terrain: Final Thoughts

The 2012 GMC Sierra 1500 SLE All Terrain is an eloquent demonstration of why so many drivers from so many different walks of life flock to full size trucks - especially crew cab trucks like this one. It's impossible not to feel safe and secure when behind the wheel of this massive vehicle, and with so much interior room available the truck can haul a full load of workers, family members or whatever you might need to cram inside its cabin with the rear bench folded up. Throw in the almost-six-foot cargo bed and the truck's utility becomes inescapable.

As a pickup, the Sierra excels. As a daily driver replacement for say, a full-size sedan or a crossover vehicle, there are some caveats. Yes, the truck is comfortable to drive but not nearly as compliant as an SUV that's not riding on a stiff, full-frame platform. There is also the question of fuel economy, as the Sierra SLE will drain its tank faster than any family car on the market. That being said, the Sierra isn't competing against smaller sedans and crossovers - it's designed to hold its own both on and off-road against the current crop of full-size trucks, and it accomplishes this goal with exceptional confidence and a touch of style.