GMC Sierra HD (2015)

GMC Sierra HD design and exterior features

Sierra HD trucks have a new face that conveys GMC's professional grade aesthetic with greater technical precision, including an all-new headlamp and grille design, power-dome hood - with specific badging on Duramax-equipped models - and a one-piece chrome bumper (body-color bumper on Denali). SLT and Denali models feature GMC's signature C-shaped LED daytime running lamps within the headlamp housings.

The new exterior design backs up its bold, advanced styling with efficiency-enhancing functionality. Improved aerodynamics allow the trucks to slip through the air with less drag and reduced wind noise, while the new grille design supports enhanced engine-cooling performance. It enhances efficiency and ensures Sierra HD delivers optimal performance under the toughest conditions, such as towing on a mountain grade.

New inlaid doors, which fit into recesses in the bodyside, help reduce wind noise for a quieter cab, while details including like the roof and tailgate spoiler were tuned in the wind tunnel to smooth airflow over the truck for reduced noise and improved aerodynamic efficiency.

Like the 2014 Sierra 1500, a new double cab body replaces the previous extended cab. It features longer, front-hinged rear doors with outside pull handles at the rear, providing improved access in tight parking spaces. New structural B-pillars were added to add to a solid feel.

Unlike trucks with rear-hinged doors, Sierra's double cab design allows rear passengers to enter and exit the vehicle with the front doors remaining closed. Crew cabs feature resized doors, too, including longer rear doors, which also make it easier to climb in and out of the rear seat.

Approximately 67 percent of each cab is constructed with high-strength and ultra-high-strength steels, used in the A-pillars, B-pillars, rockers and roof rails, as well strategic sections on the interior structure. Ultra-high-strength steel is used in areas of the rocker panels and underbody to help improve performance in crashes.

Cargo box innovations

GMC Sierra HD models are available with 6'6" and 8' box lengths that are stronger and more durable, easier to use and offer greater cargo flexibility. The new CornerStep rear bumper - introduced on Sierra 1500 - is standard. It features integrated steps at each corner designed to accommodate large boots, with textured pads for sure-footed grip.

Sierra HD's boxes also feature four integrated cargo tie-down provisions built into the lower corners and new, standard upper tie-downs. The patented upper hooks - each rated at 250 pounds - can be placed in several locations around the upper bed rails, providing flexibility for securing loads of all shapes and sizes.

The EZ Lift-and-Lower tailgate is standard on SLE, SLT and Denali models. An internal torsion bar in the tailgate reduces the effort to raise and lower it, while a rotary damper allows for a controlled and more gradual lowering motion when opening. The tailgate is also easily removable without tools.

LED cargo box lighting is standard on SLE, SLT and Denali models. Two LED lights are mounted under the box side rails and are activated by a switch on the instrument panel, providing a light source when a tonneau cover is installed or a flashlight isn't available.

The boxes come with a two-tier loading design and offers more than four feet of loading space between the wheel houses, allowing standard 4' x 8' sheets of plywood to stack flatly on the box floor. There is also more than five feet of load space between the box walls. An available, factory-installed spray-in bed liner provides protection for the box floor and walls.

The two-tier design allows customers to insert a platform to separate items during hauling or conceal valuables below, such as power tools. It incorporates resting points at the same level as the tops of the wheel houses - enabling the platform to effectively divide the box into upper and lower sections. There are also built-in provisions for cargo bulkheads to subdivide the box even further.

A wide range of utility-enhancing accessories offered through GMC dealers makes Sierra HD cargo boxes more functional. They include tool boxes, bed liners, bed mats, box nets, ladder racks and more.

Intuitive, integrated interior

The 2015 Sierra HD lineup benefits from interior introduced on the 2014 Sierra 1500. Premium materials, greater attention to detail and purposeful technologies define the passenger space, with soft-touch materials and available aluminum trim providing premium accents to an interior designed to be a productive, easy-to-use environment.

An upright instrument panel is designed for visibility and accessibility, while the knobs and buttons are large. All knobs are coated using a rubber-over-mold technology that makes them easy to grip, even with gloves.

A new instrument cluster on all models features six gauges with an available centrally located, 4.2-inch-diagonal color driver information center, with vehicle status details, a trip computer and radio and navigation readouts.

A second, high-mounted glove box with a flat floor joins the traditional box below. Each of GMC Sierra HD's doors has storage crafted to hold most beverage containers and other personal items. Along the center stack and center console are additional cupholders, discreet compartments large enough for most laptop computers, and connectivity options. Sierra HD is available with a 110-volt outlet, up to five USB ports, four 12-volt outlets and an SD card slot.

Available IntelliLink connectivity uses a reconfigurable eight-inch color touch screen with an intuitive layout and easy-to-read icons that control audio features, a Pandora app, Bluetooth phone features and available navigation with all-new map displays. Many of the system's features can be controlled by natural-language voice command, allowing drivers to keep their eyes on the road and hands on the wheel.

Sierra HD's seats use dual-density foam designed to stay comfortable over long hours and continue to look great after years of use. Leather-appointed and cloth seating are offered, and Sierra's new high-wear cloth is designed to last longer and resist staining.

Heavy-duty foundation for greater capabilities

All Sierra HD models feature fully boxed frame assemblies - 18 different assemblies that accommodate more than 150 possible vehicle configurations across the lineup. Strategic enhancements support greater capabilities, including:

• Segment-leading maximum payload of 7,374 pounds
• Segment-leading conventional towing rating of up to 19,600 pounds (with factory-installed, frame-mounted box-tube hitch)
• Maximum fifth-wheel towing rating of 23,200 pounds.

A short-long arm/torsion bar front suspension is used on all models and 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 - including snow plows - while enhancing appearance, handling, durability, tire wear and alignment.

At the rear, an asymmetrical leaf-spring design minimizes axle hop and enhances traction control efficiency. A two-stage leaf-spring design is used on 2500HD models and three-stage design is employed on 3500HD model. All models feature 3-inch-wide (76 mm) leaf springs.

The 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.

Vehicle control technologies

GMC Sierra HD's advanced vehicle control technologies are designed to make tough jobs easier and more comfortable, while also contributing to a safe driving experience, particularly when hauling cargo or towing a trailer.

StabiliTrak electronic stability control is standard on all single-rear-wheel models and - new for 2015 - 3500HD dual-rear-wheel models. It incorporates trailer sway control and hill start assist. Trailer sway control provides an added measure of confidence when towing a trailer by automatically intervening with braking and/or reduced engine power to bring the trailer under control and keep it on its intended path.

Hill start brake assist senses potential "rollback" when braking on an incline and holds full brake pressure momentarily after the driver lifts his or her foot from the pedal, preventing rollback - it is particularly effective when towing, giving the driver time to switch from the brake pedal to the gas pedal.

Available cruise control, auto grade braking, and diesel exhaust brake features help the vehicle maintain a set speed up and down grades, even when towing a heavy trailer. With the diesel exhaust brake feature, the turbocharger is used to smoothly and quietly create additional backpressure in the engine to help slow the vehicle. The combination of the exhaust brake and the automatic transmission downshifts helps the driver maintain the desired speed, even on steep grades.

Additional driver control features include four-wheel disc brakes, which are standard on all models, and four-wheel, four-channel ABS, which is standard on all single- and dual-rear-wheel models.

A rear-vision camera system is standard on SLE, SLT and Denali to give the driver a view of items behind the vehicle. It can also assist with lining up in front of a trailer.

Proven 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 is engineered to deliver excellent performance and efficiency, especially at low-rpms. It is rated at 360 horsepower (268 kW) and 380 lb-ft of torque (515 Nm) in 2500HD models and 322 horsepower (240 kW) and 380 lb-ft (515 Nm) in 3500HD.

The 6.0L engine is also available in a bi-fuel model that features special hardened valves and valve seats that enables it to run on compressed natural gas or gasoline. The CNG fuel system is installed by a GM supplier and completed vehicles are delivered directly to the customer, making the purchase process as seamless as ordering any other option.

The Duramax 6.6L diesel and Allison 1000 six-speed automatic transmission powertrain combination is available on all 2500HD and 3500HD models, with highlights that include:

• 397 horsepower (296 kW) at 3,000 rpm
• 765 lb-ft of torque (1,037 Nm) at 1,600 rpm
• High-pressure (30,000 psi/2,000 bar) Piezo-actuated fuel system for greater fuel efficiency, improved performance and reduced emissions
• Variable vane turbocharger that also acts as an exhaust brake to help control or slow the vehicle's speed
• Selective catalytic reduction after-treatment system using diesel exhaust fluid 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 optimized to provide about 700 miles (1,125 km) between diesel particulate filter regenerations
• 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.