Used 2012 GMC Sierra 2500 HD Extended Cab Pickup Used 2012
GMC Sierra 2500 HD Extended Cab Pickup

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KBB Editor's Overview

By Editorial Staff

Although many people consider GMC and Chevrolet's trucks to be interchangeable, GMC has been working hard to establish its own identity, something the company likes to call "professional grade." The 2012 GMC Sierra Heavy Duty (HD) trucks are a good example of this new image, sharing almost all of their parts with the Chevrolet Silverado HD trucks, but adding more upscale features such as the Denali trim line, which has no equal on the Chevy side. The 2012 Sierra HD trucks are a powerful lineup of 3/4-ton and 1-ton models, made all the better by last year's improvements to the frame, suspension and Duramax diesel engine. And, while the 2012 GMC Sierra HD trucks are not the most powerful in the segment, they do take top honors for fifth-wheel and conventional towing, as well as payload.


You'll Like This Pickup If...

If you're a GMC loyalist, the 2012 GMC Sierra HD truck line is bound to keep you coming back for more. Those who worry about dirtying up the inside of their truck will appreciate the heavily vinyl trappings of the Work Truck line.

You May Not Like This Pickup If...

Although both the Ram HD and Ford Super Duty trucks look nearly identical on paper, the two competitors offer bolder styling and more upscale editions than does the 2012 GMC Sierra HD line.

What's New for 2012

The 2012 GMC Sierra HD sees a few improvements for this model year. A new hard-drive navigation radio is offered, while Work Truck models gain cruise control and lockable spare tire. Denali trims gain as standard equipment heated and cooling front seats, a heated steering wheel, a rearview camera and, on 3500 dually models, 17-inch polished wheels.

Driving It

Driving Impressions

Thanks to its torque-heavy 6.6-liter Duramax turbodiesel V8, we found that towing a 10,000-pound trailer behind the 2012 GMC Sierra 2500 HD truck posed absolutely no challenge whatsoever. The 2012 GMC HD's available Duramax turbodiesel develops 397 horsepower and 765 pound-feet of torque (that's more horsepower but less torque than the Ram HD, and less horsepower and torque than the Ford PowerStroke diesel). Despite the difference in power from its main rivals, the Sierra HD still takes top honors in fifth-wheel and conventional towing, as well as payload figures. The Duramax diesel is a bit loud, but you wouldn't know it from inside the passenger compartment. One of our favorite features on the diesel truck is the "smart" exhaust-braking setup. The system works by progressively restricting the diesel's exhaust, depending on speed and grade, to help slow the rig with added compression braking. We tested a number of 2012 GMC Sierra HD trucks, with gasoline and diesel engines, long and short beds, and basic to plush trim levels. We found all exhibited a firm suspension, good steering ability and fairly compliant ride.

Favorite Features

Exhaust braking
This system progressively restricts the diesel's exhaust – depending on speed and grade – to help slow the rig with added compression braking.

Remote starting
A favorite on any vehicle, this available feature is much appreciated on working trucks that operate in hot and cold weather extremes.

Vehicle Details


The 2012 GMC Sierra HD Work Truck (WT), SLE and SLT interiors are designed to work in conjunction with the trucks' duties, yet are still nicely appointed and on Denali trims, downright opulent. While there are not as many storage bins and compartments as in the Ram and Ford HD trucks, the 2012 GMC Sierra HD nevertheless has a number of useful storage ideas for everything from laptops to the errant tool. The 2012 GMC Sierra HD truck's cab makes for the perfect mobile office, with such options as mobile Wi-Fi, Bluetooth and navigation, as well as SiriusXM NavTraffic updates and the OnStar suite of telematic aids. Denali models feature specific brushed-aluminum trim, heated and cooling 12-way power seats, power-adjustable pedals, and a Bose premium surround audio system.


The 2012 GMC Sierra 2500 and 3500 HD trucks sport a large, 3-bar chrome grille resting atop a full-size chrome bumper to create as imposing a sight as you'll ever want see in your rearview mirror. The Sierra HD's massive power dome hood is decked out in powertrain badging and features functional louvers for better engine cooling. The upscale Denali trims can be spotted by their 4-bar mesh design grille and color-keyed bumpers fitted with a mesh-style lower air intake surrounding the front tow hooks. Other features unique to the Denali include chrome door handles and accents, and polished forged-aluminum wheels.

Notable Standard Equipment

Four-wheel-disc brakes with ABS and Intelligent Brake Assist and a 6-speed automatic transmission are standard on all models, while StabiliTrak electronic stability control, Trailer Sway Control and Hill Start Assist (but not Hill Descent Control) are standard on single-rear-wheel (non-dually) models, and a "Smart" Exhaust Braking comes with the available Duramax Diesel. Also standard are chrome front and rear bumpers, engine- and transmission-oil coolers, a driver information center, tilt steering wheel, cruise control, air conditioning, automatic headlights and front tow hooks. Standard safety features include front-seat airbags and a new high-strength tubular steel-frame crossmember that improves crashworthiness.

Notable Optional Equipment

Optional (or unavailable) on base 2WD GMC Sierra Work Trucks are power locks, windows and mirrors and a rear-window defroster. The next-level SLE trim provides those plus remote keyless entry, OnStar, XM Satellite Radio, and a CD player, but not the rear-window defroster. The top-of-the-line SLT trim (available on Extended and Crew Cab models) adds leather, power seats and much more, while Denali models are fully loaded. Option packages are available, and other major options include navigation, a CD changer, a rear-seat DVD entertainment system, remote start, premium wheels, a sunroof, a rearview camera, an integrated trailer-brake controller and pelvic/thorax and head-curtain airbags.

Under the Hood

The 2012 GMC Sierra HD features as standard a heavy-duty Vortec 6.0-liter gasoline V8 with a cast-iron block, aluminum heads and cam-in-block variable valve timing (VVT). The VVT system allows the engine to use late intake valve closing to improve efficiency and achieve an optimal balance of low-rpm torque and free-breathing, high-rpm horsepower. The 2012 Duramax turbodiesel offers plentiful power and torque, improved strength and durability, and a "smart" exhaust braking with the Allison 1000 6-speed automatic transmission and full B20 biodiesel capability. Its NOx emissions are reduced by 63 percent via a Selective Catalyst Reduction after-treatment system that uses urea-based Diesel (Emission) Exhaust Fluid (DEF) in a 5.3-gallon tank that needs to be replenished about every 5,000 miles.

6.0-liter V8
360 horsepower @ 5,400 rpm
380 lb-ft of torque @ 4,200 rpm
EPA city/highway fuel economy: NA

6.6-liter turbodiesel V8
397 horsepower @ 3,000 rpm
765 lb-ft of torque @ 1,600 rpm
EPA city/highway fuel economy: NA


Pricing Notes

The 2012 GMC Sierra HD is offered in Work Truck (WT), SLE and SLT trim levels with prices starting at a Manufacturer's Suggested Retail Price (MSRP) of just under $30,000. The Denali models start close to $46,500. The available Duramax turbodiesel V8/Allison transmission combination adds about $7,200 to the Sierra's bottom line. Pricing for the GMC Sierra line is roughly on par with its Ram and Ford counterparts when comparably equipped. To make your best deal on a 2012 GMC Sierra HD truck, be sure to visit and check the Fair Purchase Price, which shows what others in your area paid for their trucks. Based on past experience, the Sierra's 5-year resale values should be roughly comparable to the Fords and better than the Rams.

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