GMC Sierra All Train HD

The GMC Sierra All Terrain HD concept is an exploration of heavy-duty truck capability combined with greater off-road versatility. It is highlighted by a bold exterior design, enhanced all-terrain suspension and premium details expected of a GMC - all designed to enable greater access to off-road destinations.

The new 2011 Sierra HD underpins the All Terrain HD concept, with a modified, production-based 4WD chassis and the Duramax diesel/Allison 1000 six-speed powertrain. The enhanced suspension and unique body dimensions, including increased ground clearance and wider track, as well as greater approach/departure angles, deliver off-road capability while maintaining HD levels of payload and trailering capacity.

"The Sierra All Terrain HD concept takes GMC's outstanding new HD platform to the next level, marries it to the legendary Duramax diesel/Allison transmission, and provides a heavy-duty expression of GMC's premium All Terrain package," said Lisa Hutchinson, GMC product marketing director. "It delivers the exceptional capabilities of the Sierra HD - hauling, towing and performance - and applies them to the toughest driving environments. It's the ultimate professional-grade tool for construction crews, ranchers and adventurers whose activities aren't limited by where the pavement ends."

The GMC Sierra All Terrain HD features a unique five-foot, eight-inch Crew Cab/short box body configuration that supports a wheels-at-the-corners proportion. Shorter in overall length than production Sierra HD models, the concept's dimensions contribute to greater approach/departure angles. Additional off-road elements include:

Wider, 73-inch (1,853 mm) track for greater stability
Approximately 3 inches (76 mm) greater ground clearance
Custom front upper and lower control arms
Specially constructed Fox off-road shocks with remote fluid reservoirs (integrated in the wheel house liners)
Front and rear jounce shocks
Electronic front stabilizer bar disconnection
35-inch-tall BFGoodrich KM2 "mud terrain" tires mounted on 20-inch machined aluminum wheels
Full composite underbody protection.

"The capability-enhancing attributes of the GMC Sierra All Terrain HD build on the already outstanding capabilities offered in the all-new production Sierra HD trucks," said Hutchinson. "Although it is strictly a concept, it is a pretty realistic one."

Purposeful design

From every angle, the All Terrain HD looks the part of a dedicated off-road performer, with bold, accentuated features complemented by a wide stance and tall profile.

Streamlined bumpers are designed to enhance approach/departure angles and incorporate frame-mounted recovery hooks - with integrated skid plates. A large, airflow-optimized grille maximizes cooling in tough conditions, while a forced-induction hood delivers more air to the Duramax diesel engine.

"The design of the All Terrain HD is an expression of its capabilities - strong, functional and absolutely professional grade," said Carl Zipfel, design manager. "We're excited about the design elements and exploring how they could apply to future GMCs."

Large fender flares stretch away from the body to cover the 35-inch-tall BFGoodrich tires. At the rear, the cargo box features lockable, lighted storage compartments, along with a number of tie-down cleats, including a pair in the bed floor and two on each side of the bed. A non-slip rubber pad is used on the tailgate, while two special compartments inside the cargo box provide access to a 110-volt power outlet and air compressor. A composite bed liner with a unique "circuit board" pattern provides a protective cover for the bed.


Motorized, deployable assist steps for the cab and cargo bed make it easier to enter and exit the All Terrain HD, while maximizing ground clearance during off-road driving. It also incorporates a number of industrial-grade lighting elements to provide greater visibility for safer driving where stars may be the only other source of illumination. The lighting details include:

High-intensity LED headlamp, taillamp and fog lamp lighting mounted in impact-resistant composite housings and featuring edge-lit illumination
High-intensity LED park and turn signal lamps
Smooth-appearance front marker lamps integrated behind the top edge of the windshield glass
Integrated center high-mounted stop lamp and rear marker lights mounted at the top edge of the rear window glass
LED floodlights for the cargo bed and assist steps.

The All Terrain HD is painted Iridium Metallic - a dark charcoal color that reveals a reddish, anodized inflection when viewed from certain angles. It complements other anodized and satin-metal finishes on the exterior, which give the truck a more precise and functional appearance.

The interior matches the exterior aesthetic, with premium appointments and increased functionality, including enhanced lighting. It conveys solidity and precision, blending accent details such as stainless steel mesh and satin chrome with an amplified expression of the All Terrain's premium features. Two-tone dark gray leather seats, matched with embossed carbon fiber-style leather on the seating surfaces, have red contrast stitching. Additional leather-wrapped interior features include the steering wheel, instrument panel and center console.

A new navigation radio is also featured on the GMC Sierra All Terrain HD concept and previews future radios to be offered in GMC vehicles. An integrated 80-gig hard drive contains map data for the navigation system. It eliminates the need for a map disc and provides greater storage of music from portable devices. It also features DVR-style "time lapse playback," which allows up to 20 minutes of recording/playback from the AM/FM/XM radio stations.

All Terrain chassis and suspension

Based on the chassis of the 2011 Sierra HD trucks, the All Terrain HD features a fully boxed steel frame with exceptional strength and torsional stiffness. It incorporates the production models' new independent front suspension and asymmetrical rear leaf-spring suspensions, but with a wider 73-inch (1,853 mm) track (front and rear) that enhances stability during off-road and highway driving. A production Sierra 2500HD has front and rear tracks of 68.8 inches (1,748 mm) and 67.3 inches (1,709 mm), respectively.

An increased ride height provides greater ground clearance of 21.1 inches (536 mm) at the rockers and 11.8 inches (300 mm) at the skid plates, while specialized Fox off-road shocks deliver exceptional damping on tough terrain. They were created specially for the All Terrain HD, with specific valving. The shocks feature visible, remote fluid reservoirs - connected to the shock bodies via custom hoses - mounted in the wheel house liners and are matched with front and rear jounce shocks. They add additional compression damping and more controlled rebound, which helps increase control, stability and handling.


The All Terrain HD also features electronic disconnection of the front stabilizer bar, which enables greater crawling capability on rocky terrain. The driver simply pushes a button inside the cab to disconnect it from the front suspension.

Custom upper and lower control arms for the front suspension are designed to work with the Fox off-road shocks and jounce shocks, while supporting the greater ground clearance and ride height. They contribute to the wider track, as do the aggressive 20-inch machined aluminum all-terrain wheels. The wheels are deep, with six split-spoke elements, and are constructed in a reverse drop-flange method that ensures optimal strength. They also feature a mix of satin chrome and anodized aluminum finishes, which provide durability and a premium appearance that complements the body's Iridium Metallic color.

A full composite underbody protection system shields the All Terrain HD's transmission, drivetrain, fuel tank, exhaust system and axle differentials. It starts with the front bumper, which rolls beneath the truck and leads to a composite, integral belly pan that covers a front suspension skid plate. Protective covers are also mounted beneath the driveline components, while the front and rear differentials feature direct-mounted skid plates. The rear bumper is integrated with the rear skid plate.

Powertrain details

The GMC Sierra All Terrain HD concept is propelled by the new, production 6.6L Duramax turbo-diesel V-8 and Allison 1000 six-speed automatic transmission powertrain combination offered in the 2011 Sierra HD trucks. The Duramax is rated at 397 horsepower (296 kW) and 765 lb.-ft. of torque (1,037 Nm).

The powerful 6.6L Duramax is more fuel-efficient - with up to 11-percent greater fuel economy than previous versions - and reduces NOx emissions by up to 63 percent. The powertrain's efficiency is assisted by the Allison 1000 transmission, which requires less engine power to funnel torque to the axles. It also incorporates a "smart" exhaust brake feature that helps save wear on the brakes on downhill grades, a feature available on production Sierra HDs.

With the same proven powertrain as production Sierra HD trucks, the All Terrain HD delivers comparable hauling and towing capabilities, including:

Estimated payload capacity of 2,700 pounds (1,225 kg)
Estimated conventional towing capacity of 13,000 pounds (5,896 kg)
Estimated fifth-wheel towing capacity of 15,600 pounds (7,076 kg).

The GMC Sierra All Terrain HD also features four-wheel drive, with automatic locking front and rear differentials, while the 14-inch, four-wheel disc brake system from the production Sierra HD provides the stopping power for this unique off-roader.

GMC SIERRA ALL TERRAIN HD CONCEPT SPECIFICATIONS

Body style / driveline: 5-passenger crew cab, 3/4-ton 4-wheel-drive heavy-duty pickup
Construction: body on frame
Engine: Duramax 6.6L turbo-diesel
Horsepower: 397 hp (296 kW) @ 3000 rpm
Torque: 765 Nm (1037 lb.-ft) @ 1600 rpm
Transmission: Allison 1000 six-speed automatic
Suspension
front: long- and short-arm independent with torsion bars
rear: semi-elliptic two-stage multi-leaf spring
Steering type: integral power-assisted recirculating ball
Brakes (type): power-assisted, Hydroboost brake-apply system, four-wheel disc, four-wheel ABS
Brake rotor (diameter x thickness)
front: 13.97" x 1.57" / 355 x 40 mm
rear: 14.17" x 1.34" / 360 x 34 mm
Wheel size and type: 20 x 9.5-inch aluminum
Tire type and size: BFGoodrich KM2 325/60R20
Wheelbase: 148.6" / 3774 mm
Overall length: 230.9" / 5864 mm
Overall width: 83" / 2106 mm
Overall height: 81.8" / 2077 mm
Track
front: 73" / 1853 mm
rear: 73" / 1853 mm
Minimum ground clearance
21.1" / 536 mm (at rocker panels)
11.8" / 300 mm (at skid plates)
Approach angle
front: 39°
rear: 31°
Maximum payload (est.): 2700 lbs. / 1225 kg
Maximum towing capacity (est.)
ball hitch: 13,000 lbs. / 5896 kg
fifth-wheel hitch(est.): 15,600lbs. / 7076 kg Read More!

GMC Denali XT

GMC unveiled the GMC Denali XT concept at the 2008 Chicago Auto Show. It offers a 50-percent increase in combined fuel economy over comparable small pickup trucks when running on gasoline, and it incorporates a new, muscular form in a performance-styled, hybrid sport-utility truck (SUT).

The Denali XT has a unibody architecture and rear-wheel drive, enabling its distinctive design and efficient performance. It builds on the equity of the Denali line and its reputation for advanced engineering and refinement, including the first combination of GM's two-mode hybrid system with an E85 ethanol-capable engine. Denali XT's new, more efficient 4.9L version of GM's small-block V-8 features fuel-saving technologies such as direct-injection technology and Active Fuel Management.

The engine is matched with GM's unique two-mode hybrid propulsion system, giving the powerful SUT exceptional fuel economy and uncompromising capability - including all-electric drive at low speeds. It is a powertrain combination that makes the Denali XT perfectly suited to a variety of active lifestyle activities, such as hauling skis and snowboards to the mountain or towing a sport jet boat to the lake.

"Like all GMCs, the Denali XT is functional and capable, but it blends those traits with a more efficient, sporty driving experience," said Jim Bunnell, GMC general manager. "It is a vehicle that exemplifies GMC's engineering excellence, as well as GM's commitment to hybrid and advanced technologies."

With its unibody structure, the Denali XT is lighter than conventional body-on-frame trucks, with great ride-and-handling characteristics. This design enhances fuel economy while giving the vehicle a sporty driving experience. True to its GMC Professional Grade heritage, the Denali XT is filled with technologies and features that maximize its flexibility, including a cargo space-enhancing Midgate® and height-adjustable suspension.

The Denali XT's proportions are framed around a high cowl and 123.4-inch (3,134 mm) wheelbase. This enhances the vehicle's truck functionality, but packages it in an efficient, unibody architecture.

Design and construction were spearheaded by Holden Design, within the Australian arm of GM's global design and engineering network.

"Denali XT is about working hard, playing hard and enjoying an active lifestyle," said Bunnell. "It is the same philosophy that has helped make the GMC Acadia crossover a huge hit with consumers."

Dramatic design statement

A muscular form and wide, firmly planted stance give the Denali XT a confidently capable road presence. Minimal overhangs, large wheels, sleek headlamps and a low roof profile deliver an aggressive, performance-oriented appearance.

"It is a robust yet tailored design statement that is unlike anything else on the road," said Ed Welburn, vice president, Global Design. "It has the youthful look of a custom automobile that incorporates the capability customers expect from a truck."

The Denali XT's design includes a new take on GMC's iconic grille, with a prominent, four-bar element in addition to the large, red GMC logo and signature Denali background. Flared fenders accentuate the wide road stance. The stance is also enhanced when the Denali XT is lowered on its air-adjustable suspension, which creates a sleeker appearance that simultaneously improves aerodynamics. Large, bold 23-inch wheels and custom Kuhmo tires complement the Denali XT's stance.

Inside, the Denali XT blends mechanical functionality with leather-trimmed comfort.

Billet-metal surrounds, controls and instruments convey the cold precision of an aircraft cockpit. This is balanced by the warmth of bespoke saddle-leather trimmed seats and other contact surfaces.

"The form language is smooth and structured to characterize GMC's power. The details have a deliberately contrasting mechanical aesthetic to mark GMC's engineering sophistication," said Warrack Leach, lead designer.

The interior features innovative instrumentation with "floating" red-illuminated numerals backed by surface chaplets in the clusters and a large integrated vehicle interface screen. The interior illumination was supplied by Osram.

The Denali XT seats four. The high-cowl vehicle architecture enables higher seating positions, allowing the couple distance between front and rear occupants to be reduced without compromising knee room. This packaging efficiency creates generous interior and cargo bed dimensions within a more compact package.

Truck capability

With stiffness that is greater than most conventional, body-on-frame trucks, the Denali XT's unibody structure supports a very capable truck platform. It also serves as the mounting point for a four-wheel independent suspension that gives the vehicle its performance feel on the road. The multilink front suspension features a forward-mounted steering rack and dual lower links with ball joints at the outer ends, providing sharp responses to driver input. At the rear, a four-link suspension design uses coil-over shocks and a decoupled stabilizer bar to enhance cornering control, reduce body roll and optimize longitudinal compliance. In short, it's a truck that hauls more than cargo on twisting roads.

The rear cargo area is wide, deep and flat, with no suspension or wheelhouse protrusions; the cargo floor measures 55 inches long (1,397 mm) by 47.5 inches wide (1,206 mm). It all adds up to the space to haul a wide variety of lifestyle accessories.

The easy-to-operate Midgate can be lowered to extend the cargo-carrying capacity inside the vehicle. The rear seats fold flat to provide a longer floor for carrying items such as skis, surfboards or wood from the home improvement store. A fixed rear window allowed engineers to retain the vehicle's structure, reducing mass and complexity.

The Denali XT has an estimated payload capacity of 1,100 pounds (499 kg) and a towing capacity of an estimated 3,500 pounds (1,587 kg). This capability is delivered through unique vehicle and powertrain integration, where the multiple modes of GM's two-mode hybrid system provide towing capability.

New 4.9L SIDI V-8 and two-mode hybrid system

For the first time, GM's rear-wheel-drive two-mode hybrid transmission is paired with a smaller-displacement version of the small-block engine. The new V-8 4.9L E85-capable engine powers the Denali XT with an estimated 326 horsepower (243 kW). It uses direct-injection technology to produce the power of a larger engine, but consumes less fuel and produces lower emissions.

Also, the functionality of GM's Active Fuel Management system has been expanded through the use of hybrid technologies, enhancing the cylinder-deactivating feature to further improve fuel efficiency.

The Denali XT's two-mode hybrid system is partnered with the 4.9L engine and uses an electrically variable transmission to enhance fuel efficiency in city and highway driving. In city driving, all-electric propulsion is used at low speeds; on the highway, fixed-gear operation enables efficient performance even when towing a trailer.

The specific characteristics of the Denali XT allowed the synergistic evolution of GM's small-block V-8 and two-mode hybrid beyond the recently introduced in GM two-mode hybrid products, such as the GMC Yukon Hybrid and Sierra Hybrid. During this optimization process, additional powertrain technologies have been integrated, including Active Thermal Management, which transfers thermal energy from one driveline component to another to improve efficiency; and a high-efficiency axle configuration, which fundamentally reduces the losses normally associated with conventional axle configurations. Read More!