Diversity defines the Sierra HD lineup. There are 10 Sierra 2500HD models, eight 3500HD models and six Sierra Denali HD models. Among them are regular cab, extended cab and crew cab body styles offered in 2WD and 4WD, as well as single- and dual-rear-wheel configurations – all available with either a standard gas V-8 or the powerful Duramax 6.6L turbo-diesel.
![2012 GMC Sierra HD photo 2012 GMC Sierra HD photo](http://www.autospectator.com/cars/files/images/2012-GMC-Sierra-HD-023.jpg)
Along with a diverse range of models and configurations is the capability to handle just about any job Sierra HD owners can throw at their trucks. Highlights include:
![2012 GMC Sierra HD photo 2012 GMC Sierra HD photo](http://www.autospectator.com/cars/files/images/2012-GMC-Sierra-HD-037.jpg)
Best-in-class towing capability of 23,000 pounds (10,432 kg)
Best-in-class conventional-hitch trailering capacity of 18,000 pounds (8.164 kg) – available fourth-quarter 2011
Best-in-class maximum payload of 7,215 pounds (3,272 kg)
Fully-boxed, high-strength-steel frames
6.6L Duramax diesel delivers 397 horsepower (296 kW) and 765 lb.-ft. of torque (1,037 Nm), as well as B20 biodiesel capability
Standard 36-gallon (136 L) fuel tank and engine efficiency enable up to 680 miles (1,090 km) between fill-ups with the 6.6L Duramax turbo diesel
Smart exhaust brake feature provides greater control on grades and reduced brake pad wear
An array of control features, including trailer sway control, integrated trailer brake control, hill start assist, automatic grade braking, intelligent brake assist and larger brakes
Best-in-class conventional-hitch trailering capacity of 18,000 pounds (8.164 kg) – available fourth-quarter 2011
Best-in-class maximum payload of 7,215 pounds (3,272 kg)
Fully-boxed, high-strength-steel frames
6.6L Duramax diesel delivers 397 horsepower (296 kW) and 765 lb.-ft. of torque (1,037 Nm), as well as B20 biodiesel capability
Standard 36-gallon (136 L) fuel tank and engine efficiency enable up to 680 miles (1,090 km) between fill-ups with the 6.6L Duramax turbo diesel
Smart exhaust brake feature provides greater control on grades and reduced brake pad wear
An array of control features, including trailer sway control, integrated trailer brake control, hill start assist, automatic grade braking, intelligent brake assist and larger brakes
![2012 GMC Sierra HD photo 2012 GMC Sierra HD photo](http://www.autospectator.com/cars/files/images/2012-GMC-Sierra-HD-032.jpg)
Technology features include available mobile WiFi, USB connectivity, Bluetooth for phone connectivity, SiriusXM Satellite Radio, OnStar 9.0 and navigation that help make work on the road easier.
The increases in payload and towing capability are due to a variety of enhancements, including beefier rear springs and U-bolts, revised rear axle tubes and shock tuning, revised pickup box cross sills and other structural enhancements, modified box mounting on the frame and a revised trailer hitch receiver. The changes take the maximum gross vehicle weight rating from 12,800 pounds (5,806 kg) to 13,400 pounds (6,078 kg).
![2012 GMC Sierra HD photo 2012 GMC Sierra HD photo](http://www.autospectator.com/cars/files/images/2012-GMC-Sierra-HD-031.jpg)
Sierra lineup
Work Truck, SLE and SLT models are offered, as well as the distinctive Sierra Denali HD models, which blend heavy-duty capability with distinctive style and luxury appointments.
New and revised features for 2012 include an available hard-drive navigation radio with CD/DVD and USB port features and a new exterior color: Quicksilver Metallic. Also, a number of popular features offered on the Work Truck trim level are now standard, including cruise control, spare tire lock and, exclusively on the 3500HD, the outside high-visibility camper-style mirrors.
A number of previously optional features are now standard on 2012 Sierra Denali HD models, including heated and cooled front seats, leather-wrapped heated steering wheel and the rear vision camera. The high-idle switch is now available on the Denali 2500HD and the Heavy Duty Trailering package and Eaton® automatic locking differential are now standard on all Sierra 3500HD models.
Seventeen-inch forged polished aluminum wheels are new and standard on 3500 Denali HD with dual rear wheels and available on 3500HD SLT models with dual rear wheels.
![2012 GMC Sierra HD photo 2012 GMC Sierra HD photo](http://www.autospectator.com/cars/files/images/2012-GMC-Sierra-HD-028.jpg)
Sierra Denali Details
Sierra Denali HD models are offered exclusively in the crew cab body style, in regular- and long-box configurations and in 2WD and 4WD. The Duramax diesel/Allison 1000 powertrain is available across the board.
A Denali-specific chrome grille makes the truck instantly recognizable. Additional chrome trim and body-color bumpers further distinguish it. Sierra Denali also offers a unique combination of interior style and luxury, including standard nuance perforated leather-appointed front seats, with heated and cooled, 12-way power-adjustable front seats. A Denali-exclusive leather-wrapped and heated steering wheel, which features wood-grain accents and a host of auxiliary controls, is standard.
Denali models feature a unique center console, enhanced interior bright work and detailed, highly finished embossed sill plates. The center console has woodgrain trim an a lid that conceals the cupholders, creating a more finished and refined appearance.
![2012 GMC Sierra HD photo 2012 GMC Sierra HD photo](http://www.autospectator.com/cars/files/images/2012-GMC-Sierra-HD-033.jpg)
Sierra HD exterior features
Sierra 2500HD and 3500HD models are distinguished by a power dome-style hood with a louvered design, as well as a wide grille with chrome accents and full-width chrome steel front bumper. A lineup of 17- (Dually), 18- and 20-inch wheel/tire combinations are offered. Standard and available exterior features also include:
Outside high-visibility vertical camper-style mirrors are standard on 3500HD Work Truck and available on 2500HD Work Truck.
Heated outside mirrors are available on all models; heated outside and power-adjustable vertical camper-style mirrors with turn signal indicators are available on 2500HD SLE, SLT and Denali and standard on 3500HD SLE, SLT and Denali models.
Front recovery hooks are standard on all models.
EZ-Lift locking tailgate feature is available on all models.
Dual cargo lamps are standard on all models.
Seventeen-inch steel wheels are standard on 2500HD Work Truck and all 3500HD SRW models.
Seventeen-inch chrome-clad steel wheels are available on 2500HD Work Truck.
Seventeen-inch machine-finish aluminum wheels are standard on 2500HD SLE.
Seventeen-inch forged polished aluminum wheels are standard on 3500 Denali HD with dual rear wheels and available on SLE and SLT with dual rear wheels.
Eighteen-inch painted steel wheels are available on 2500HD Work Truck and standard on 3500HD Work Truck with SRW with the 6.0L engine (available with Duramax diesel).
Eighteen-inch forged polished aluminum wheels are standard on 2500HD SLT and Denali models and on 3500HD SRW SLE, SLT and Denali models.
Twenty-inch forged polished aluminum wheels are available on 2500HD SLE, SLT and Denali.
Exterior color choices include: Onyx Black, Midnight Blue Metallic (late availability), Mocha Steel Metallic (late availability), Stealth Grey Metallic, Steel Grey Metallic (late availability), Summit White, Fire Red, Quicksilver Metallic and Carbon Black Metallic (late availability).
Heated outside mirrors are available on all models; heated outside and power-adjustable vertical camper-style mirrors with turn signal indicators are available on 2500HD SLE, SLT and Denali and standard on 3500HD SLE, SLT and Denali models.
Front recovery hooks are standard on all models.
EZ-Lift locking tailgate feature is available on all models.
Dual cargo lamps are standard on all models.
Seventeen-inch steel wheels are standard on 2500HD Work Truck and all 3500HD SRW models.
Seventeen-inch chrome-clad steel wheels are available on 2500HD Work Truck.
Seventeen-inch machine-finish aluminum wheels are standard on 2500HD SLE.
Seventeen-inch forged polished aluminum wheels are standard on 3500 Denali HD with dual rear wheels and available on SLE and SLT with dual rear wheels.
Eighteen-inch painted steel wheels are available on 2500HD Work Truck and standard on 3500HD Work Truck with SRW with the 6.0L engine (available with Duramax diesel).
Eighteen-inch forged polished aluminum wheels are standard on 2500HD SLT and Denali models and on 3500HD SRW SLE, SLT and Denali models.
Twenty-inch forged polished aluminum wheels are available on 2500HD SLE, SLT and Denali.
Exterior color choices include: Onyx Black, Midnight Blue Metallic (late availability), Mocha Steel Metallic (late availability), Stealth Grey Metallic, Steel Grey Metallic (late availability), Summit White, Fire Red, Quicksilver Metallic and Carbon Black Metallic (late availability).
![2012 GMC Sierra HD photo 2012 GMC Sierra HD photo](http://www.autospectator.com/cars/files/images/2012-GMC-Sierra-HD-007.jpg)
Sierra HD interior standard and available features
Sierra HD models are designed to be comfortable and convenient while on the job, with features that include 170-degree-opening rear access doors on extended cab models and numerous storage compartments that provide covered access for everything from work gloves to laptops.
For those who work out of their truck, Sierra HDs serve as mobile workspaces, offering mobile WiFi as a dealer-installed option, USB connectivity, Bluetooth for phone connectivity, SiriusXM Satellite Radio and a navigation system. Multiple charge points enable multiple electronic devices to operate simultaneously.
Cold-weather customers warm up quicker with the Duramax 6.6L engine, which has a starting time on par with gas engines. Its glow plug cycle time takes no more than 3 seconds in temperatures as low as -20 F (-29 C).
Highlights of all models’ standard and available interior features include:
Dual-zone automatic climate control is standard on Denali and SLT and available on SLE; single-zone manual air conditioning is standard on Work Truck and SLE.
AM/FM stereo is standard on Work Truck models (not available with SiriusXM Satellite Radio).
CD/DVD/MP3-capable audio system is available on select crew cab models.
Navigation radio with MP3-compatible CD/DVD player and USB port is available on Denali and SLT models.
SiriusXM Satellite Radio is standard on SLE, SLT and Denali models and available on Work Truck.
SiriusXM NavTraffic feature is available on 2500 SLE, SLT and Denali and 3500 SLT and Denali.
Bluetooth hands-free phone connectivity is standard on Denali and SLT models and available on Work Truck and SLE.
Driver Information Center is standard on all models.
Rear-seat entertainment system is available on Denali and SLT crew cab models.
Auto-dimming rearview mirror is standard on 2500 Denali HD and SLT and available on 2500HD SLE; and standard on 3500HD SLE, SLT and Denali.
Power-adjustable pedals are standard on Denali and available on SLE and SLT models.
Two auxiliary 12-volt power outlets are standard on all models and mounted on the instrument panel.
Remote vehicle starter system is standard on Denali and SLT and available on SLE models.
Vinyl seat trim and rubberized floor covering is standard on Work Truck models. Cloth seat trim is available.
Premium cloth seat trim is standard on SLE models.
Leather-appointed front seat trim is standard on Denali and SLT and available on SLE models.
Front 40/20/40-split front bench seat is standard on Work Truck models and SLE models. SLE includes locking storage in the seat cushion.
Front bucket seats with 10-way power driver and passenger seat adjusters are standard on SLT models. Front bucket seats with six-way power adjusters are available on SLE models.
Front bucket seats with 12-way power driver and passenger seat adjusters are standard on Denali models.
Leather-wrapped steering wheel is standard on SLE and SLT models and available on Work Truck when you get radio controls.
Leather-wrapped and heated steering wheel with auxiliary controls is standard on Denali models.
Leather-appointed and heated and cooled front seats are standard on Denali models and available on SLT.
Power-operated sunroof is available on Denali and SLT extended cab and crew cab models. The sunroof retracts above the roof on extended cab and inside the roof on crew cab models.
Power-operated rear sliding window is available on Denali, SLT and SLE models.
Interior trim colors include: Ebony, Dark Cashmere/Light Cashmere, Dark Titanium/Light Titanium and Dark Titanium.
AM/FM stereo is standard on Work Truck models (not available with SiriusXM Satellite Radio).
CD/DVD/MP3-capable audio system is available on select crew cab models.
Navigation radio with MP3-compatible CD/DVD player and USB port is available on Denali and SLT models.
SiriusXM Satellite Radio is standard on SLE, SLT and Denali models and available on Work Truck.
SiriusXM NavTraffic feature is available on 2500 SLE, SLT and Denali and 3500 SLT and Denali.
Bluetooth hands-free phone connectivity is standard on Denali and SLT models and available on Work Truck and SLE.
Driver Information Center is standard on all models.
Rear-seat entertainment system is available on Denali and SLT crew cab models.
Auto-dimming rearview mirror is standard on 2500 Denali HD and SLT and available on 2500HD SLE; and standard on 3500HD SLE, SLT and Denali.
Power-adjustable pedals are standard on Denali and available on SLE and SLT models.
Two auxiliary 12-volt power outlets are standard on all models and mounted on the instrument panel.
Remote vehicle starter system is standard on Denali and SLT and available on SLE models.
Vinyl seat trim and rubberized floor covering is standard on Work Truck models. Cloth seat trim is available.
Premium cloth seat trim is standard on SLE models.
Leather-appointed front seat trim is standard on Denali and SLT and available on SLE models.
Front 40/20/40-split front bench seat is standard on Work Truck models and SLE models. SLE includes locking storage in the seat cushion.
Front bucket seats with 10-way power driver and passenger seat adjusters are standard on SLT models. Front bucket seats with six-way power adjusters are available on SLE models.
Front bucket seats with 12-way power driver and passenger seat adjusters are standard on Denali models.
Leather-wrapped steering wheel is standard on SLE and SLT models and available on Work Truck when you get radio controls.
Leather-wrapped and heated steering wheel with auxiliary controls is standard on Denali models.
Leather-appointed and heated and cooled front seats are standard on Denali models and available on SLT.
Power-operated sunroof is available on Denali and SLT extended cab and crew cab models. The sunroof retracts above the roof on extended cab and inside the roof on crew cab models.
Power-operated rear sliding window is available on Denali, SLT and SLE models.
Interior trim colors include: Ebony, Dark Cashmere/Light Cashmere, Dark Titanium/Light Titanium and Dark Titanium.
![2012 GMC Sierra HD photo 2012 GMC Sierra HD photo](http://www.autospectator.com/cars/files/images/2012-GMC-Sierra-HD-017.jpg)
Sierra HD Powertrains
A Vortec 6.0L gas V-8 with variable valve timing is matched with the Hydra-Matic 6L90 six-speed automatic transmission as the standard powertrain across the Sierra HD model range. This combination delivers excellent performance and efficiency, with an emphasis on low-rpm performance.
The Duramax 6.6L diesel and Allison 1000 six-speed automatic transmission powertrain combination is available on all 2500HD and 3500HD models – including Denali HD – helping Sierra HD trucks deliver best-in-class capabilities. Highlights include:
397 horsepower (296 kW) at 3000 rpm.
765 lb.-ft. of torque (1,037 Nm) at 1600 rpm.
High-pressure (30,000 psi/2,000 bar) Piezo-actuated fuel system for greater fuel efficiency, improved performance and reduced emissions.
Exhaust brake system that enables controlled vehicle slowdown on downhill grades without actuating the brakes.
Selective catalytic reduction after-treatment system using diesel exhaust fluid (DEF) injection to provide the best overall diesel characteristics and performance – with a range of about 5,000 miles (8,000 km) between DEF refills.
Combustion and after-treatment have been optimized to provide about 700 miles (1,125 km) between diesel particulate filter regenerations – a 75-percent improvement over the previous system and significant contributor to improved fuel efficiency, as the regeneration process requires additional fuel.
B20 biodiesel capability for an alternative fueling option.
The Allison 1000 features driver shift control with tap up/tap down shifting and a patented elevated idle mode cab warm-up feature. Also, the tow/haul mode reduces shift cycling for better control and improved cooling when towing or hauling heavy loads.
765 lb.-ft. of torque (1,037 Nm) at 1600 rpm.
High-pressure (30,000 psi/2,000 bar) Piezo-actuated fuel system for greater fuel efficiency, improved performance and reduced emissions.
Exhaust brake system that enables controlled vehicle slowdown on downhill grades without actuating the brakes.
Selective catalytic reduction after-treatment system using diesel exhaust fluid (DEF) injection to provide the best overall diesel characteristics and performance – with a range of about 5,000 miles (8,000 km) between DEF refills.
Combustion and after-treatment have been optimized to provide about 700 miles (1,125 km) between diesel particulate filter regenerations – a 75-percent improvement over the previous system and significant contributor to improved fuel efficiency, as the regeneration process requires additional fuel.
B20 biodiesel capability for an alternative fueling option.
The Allison 1000 features driver shift control with tap up/tap down shifting and a patented elevated idle mode cab warm-up feature. Also, the tow/haul mode reduces shift cycling for better control and improved cooling when towing or hauling heavy loads.
![2012 GMC Sierra HD photo - 2012 GMC Sierra HD photo -](http://www.autospectator.com/cars/files/images/2012-GMC-Sierra-HD-013.jpg)
Sierra HD chassis and suspension
All Sierra HD models feature fully boxed frame assemblies – 18 different assemblies that accommodate all of the range’s configurations. Redesigned last year, the frames have reinforced cross sections and use more high-strength steel for greater durability, higher towing capacity and improved ride and handling. The front sections are hydroformed. Additional chassis and suspension features include:
Front axle weight rating up to 6,000 pounds (2,721 kg) front gross axle weight rating (FGAWR), enabling a snow plow to be used on all 4WD cab configurations with the available snow plow prep package.
Short-long arm/torsion bar front suspension features forged steel upper control arms and precision-machined cast iron lower control arms.
Five different torsion bar rates support five different front gross axle weight ratings to help stabilize the range of trim heights of various models under load, while enhancing appearance, handling, durability, tire wear and alignment. The trim height is adjusted on each bar via a single bolt, easily allowing the height to be changed to account for the weight of a snow plow or other accessories.
An upper shock mount attachment design that’s positively connected to the frame with two fasteners, eliminating squeaks and clunks, while supporting higher load capability and increased durability.
Asymmetrical leaf-spring design that minimizes axle hop and enhances traction control efficiency.
Two-stage leaf-spring design on 2500HD models and three-stage design on 3500HD model. All models feature 3-inch-wide (76 mm) leaf springs.
Z71 Off Road suspension is available on SLE and SLT models and includes 35mm deflective disk twin-tube shock absorbers, off-road jounce bumpers, 33mm front stabilizer bar and a skid plate package.
Four-wheel disc brakes with hydroboost are standard on all models.
Four-wheel, four-channel ABS is standard on all single-rear-wheel models and a three-channel system is standard on dual-rear-wheel models.
A Sierra 3500HD crew cab/long box can tow up to 23,000 pounds (10,432 kg) with a fifth-wheel hitch.
The maximum payload (3500HD) is 7,215 pounds (3,273 kg).
The frame-mounted hitch for conventional trailering has a box-tube design and supports up to 18,000 pounds (8,164 kg).
Short-long arm/torsion bar front suspension features forged steel upper control arms and precision-machined cast iron lower control arms.
Five different torsion bar rates support five different front gross axle weight ratings to help stabilize the range of trim heights of various models under load, while enhancing appearance, handling, durability, tire wear and alignment. The trim height is adjusted on each bar via a single bolt, easily allowing the height to be changed to account for the weight of a snow plow or other accessories.
An upper shock mount attachment design that’s positively connected to the frame with two fasteners, eliminating squeaks and clunks, while supporting higher load capability and increased durability.
Asymmetrical leaf-spring design that minimizes axle hop and enhances traction control efficiency.
Two-stage leaf-spring design on 2500HD models and three-stage design on 3500HD model. All models feature 3-inch-wide (76 mm) leaf springs.
Z71 Off Road suspension is available on SLE and SLT models and includes 35mm deflective disk twin-tube shock absorbers, off-road jounce bumpers, 33mm front stabilizer bar and a skid plate package.
Four-wheel disc brakes with hydroboost are standard on all models.
Four-wheel, four-channel ABS is standard on all single-rear-wheel models and a three-channel system is standard on dual-rear-wheel models.
A Sierra 3500HD crew cab/long box can tow up to 23,000 pounds (10,432 kg) with a fifth-wheel hitch.
The maximum payload (3500HD) is 7,215 pounds (3,273 kg).
The frame-mounted hitch for conventional trailering has a box-tube design and supports up to 18,000 pounds (8,164 kg).
![2012 GMC Sierra HD photo 2012 GMC Sierra HD photo](http://www.autospectator.com/cars/files/images/2012-GMC-Sierra-HD-011.jpg)
Sierra HD safety and crash-avoidance features
StabiliTrak electronic stability control system is standard on all single-rear-wheel models.
Large, four-wheel disc brakes with four-wheel ABS are standard on all models.
High-strength steel tubular frame cross member enhances safety and improves crashworthiness.
Seat pelvic/thorax and head curtain side air bags available on 2500HD
Rear vision camera is available (standard on Denali models).
Trailer sway control system on all single-rear-wheel models.
Hill start assist is standard on single-rear-wheel models.
Trailer sway control system provides an added measure of confidence when towing a trailer. The system senses conditions of trailer sway and intervenes with braking and/or reduced engine power to bring the trailer under control and keep it on its intended path. The system will use electric trailer brakes when a trailer is plugged into the standard wiring harness of the truck and requires no input from the driver.
Large, four-wheel disc brakes with four-wheel ABS are standard on all models.
High-strength steel tubular frame cross member enhances safety and improves crashworthiness.
Seat pelvic/thorax and head curtain side air bags available on 2500HD
Rear vision camera is available (standard on Denali models).
Trailer sway control system on all single-rear-wheel models.
Hill start assist is standard on single-rear-wheel models.
Trailer sway control system provides an added measure of confidence when towing a trailer. The system senses conditions of trailer sway and intervenes with braking and/or reduced engine power to bring the trailer under control and keep it on its intended path. The system will use electric trailer brakes when a trailer is plugged into the standard wiring harness of the truck and requires no input from the driver.
The hill start assist system is automatically engaged when sensors detect the vehicle is on grade of approximately 5 percent or greater. It holds the brakes for 1.5 seconds or until the gas pedal is pressed, preventing rollback – it is particularly effective when towing, giving the driver time to switch from the brake pedal to the gas pedal without rolling.
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