Auto Tech 2012

GMC Sierra All Terrain HD Concept, 2011

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 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:

•     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.

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.

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:

•     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.

The 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:
   = 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

Cadillac SRX, 2012

A new 3.6L V-6 - the segment's most powerful standard engine - headlines updates to the 2012 Cadillac SRX. It enhances a combination of performance, technology and refinement that is resonating with more luxury crossover customers.

Cadillac SRX retail sales rose 17.7 percent in the first half of 2011, building on a record-setting 2010 sales increase of 150 percent.

The new 3.6L - known by its "LFX" engine code - is the sole engine offered in the Cadillac SRX. It delivers 16-percent more horsepower (308 hp / 230 kW) than the previous V-6 and provides greater low-rpm torque. Vehicle responsiveness is dramatically improved in all operating conditions - launch from a standstill, around town maneuvering in traffic, passing maneuvers and full-throttle acceleration. It is matched with the Hydra-Matic 6T70 six-speed automatic transmission, which features a driver-selectable Eco feature that alters the shift points and throttle progression to help optimize fuel economy.

Cadillac SRX also brings enhanced features for 2012, as well as updates that make it quieter and more refined - including new sound-absorbing material placed strategically throughout the vehicle. The Base and Sport suspension systems have been revised to improve the ride quality.

The feature and content:

•     Standard Bluetooth phone connectivity on all models, with on-screen caller identification
•     OnStar Turn-by-Turn automated directions are loaded to the vehicle
•     Improved voice recognition for phone activation, navigation and radio station changes
•     A heated steering wheel on the Luxury, Performance and Premium Collections
•     Door lock switches on the driver and passenger door panels as well as the center console
•     Cruise control buttons on the steering wheel
•     Memory seat set - the occupant can set the seating position simply by pressing "set" and the number simultaneously
•     Backlighting for map lights in the overhead console
•     A new machined-face finish on the 20-inch wheels, which are standard on Performance and Premium Collections
•     Available all-ebony interior trim
•     One new exterior color: Xenon Blue Metallic.

Popular features returning for 2012 include a moveable cargo fence and large under-floor storage space in the rear, a liftgate that can be programmed to stop at different heights and the UltraView sunroof that covers 70 percent of the vehicle roof.

The new and enhanced elements that contribute to a quieter ride include new acoustic material in the upper instrument panel, front-of-dash area, the center console area and the inner fenders, as well as laminated glass used in the front side glass. There is also a new laminated structural barrier used under the second-row seat to block noise.

Inside the LFX
The Cadillac SRX's new LFX 3.6L direct-injected V-6 delivers an SAE-certified 308 horsepower (230 kW) and 265 lb.-ft. of torque (359 Nm), with efficiency-enhancing features including direct injection and continuously variable valve timing. Peak torque is achieved at only 2,400 rpm and is maintained through 5,300 rpm. The LFX is also E85 ethanol-capable.

The LFX engine is a technically advanced 60-degree V-6 with dual-overhead camshafts, continuously variable valve timing and direct injection. Supporting elements that contribute to its performance, refinement and durability:

•     The cylinder block and cylinder heads are cast in aluminum for low weight.
•     A composite intake manifold saves approximately 5.5 pounds (2.5 kg) over the weight of a comparable aluminum intake. It also has a comparatively small radiated surface area to help it maintain excellent noise and vibration characteristics.
•     An integrated cylinder head/exhaust manifold design saves approximately 13 pounds (6 kg) per engine when compared with a comparable engine with separate head/manifold assemblies.
•     The cylinder heads include four valves per cylinder, with a dual overhead camshaft design incorporating infinitely variable cam phasing.
•     A forged steel crankshaft provides optimal strength in the bottom end, while the connecting rods are made of powdered metal that features a higher ratio of copper, which makes them stronger and enables them to be lighter.
•     The pistons are made of lightweight cast aluminum and feature a friction-reducing polymer coating on the skirts , as well as fully floating wrist pins, which also help reduce friction. Less weight in the pistons means less reciprocating mass in the engine, which in turn means less inertia and greater operating efficiency.
•     Pressure-actuated oil squirters drench the underside of each piston and the surrounding cylinder wall with an extra layer of cooling, friction-reducing oil.
•     A cast aluminum oil pan is stiffer to improve powertrain rigidity and reduce vehicle vibration. It bolts to the transmission bell housing as well as the engine block, eliminating points of vibration. Cast aluminum dampens internal engine noise better than a conventional stamped steel pan and is structurally stiffer.
•     Optimized-flow fuel injectors and the integrated exhaust manifolds/cylinder heads promote lower emissions.

To help achieve their performance goals, the Cadillac SRX's engineers redesigned the exhaust system with dual runners from the engine to a collection point farther rearward in the vehicle. The diameter and length of the pipes were specifically tuned to improve low-end torque from 1,200 to 3,000 rpm.

High-pressure exhaust pulses from each of the cylinders in the engine are timed to arrive at this collection point so that they phase together in a precise way. This tuning effect, which is called scavenging, literally pulls exhaust gases out of the engine by synchronizing high and low pressure pulses from each cylinder. Peak torque now occurs at a very low 2,400 rpm and remains high all the way through 5,300 rpm. The torque and power improvements were achieved while maintaining quiet performance.

The LFX engine is paired with the Hydra-Matic 6T70 electronically controlled six-speed automatic transmission, with tap up/tap down driver control. A wide overall ratio spread of 6.04:1 allows a "steep" first gear, as well as a "tall" overdrive top gear for low-rpm highway cruising. Acceleration is maximized, as is fuel economy. Engine noise is also lower during cruising. Because of the wide ratio spread (6.04:1), first gear is a very high ratio, which provides brisk acceleration from a stop. Sixth, however, is an overdrive ratio, which keeps the engine revolutions as low as possible for highway cruising, reducing engine friction losses and improving fuel economy.

A driver-selectable Eco feature alters the shift points of the 6T70 to enhance fuel economy by up to 1 mpg. A clutch was added to the variable displacement air conditioning compressor to enhance fuel economy. The compressor is only run when needed and provides no drag when turned off.

Chassis and suspension
The Cadillac SRX has a four-wheel independent suspension system and a standard rack-and-pinion hydraulic steering system - and offers a variable-effort, speed-sensitive steering system - with tuning biased for sport sedan-style driving and strong on-center feel. StabiliTrak electronic stability control is standard and works with the standard four-wheel-disc/four-channel-ABS braking system.

The core elements of the chassis and suspension systems include:

•     An independent MacPherson strut suspension system is standard on all models, featuring a direct-acting stabilizer bar and hydraulic ride bushings.
•     An independent "H-arm" rear suspension incorporates a lightweight hollow aluminum lower control arm and a hollow stabilizer bar.
•     Power-assisted rack-and-pinion steering is standard on Base and the Luxury Collections.
•     Power-assisted variable-effort and speed-sensitive rack-and-pinion steering system is standard on the Performance and Premium Collections.
•     A rear axle ratio of 3.39 is standard on all models.
•     A trailering package is available on the Luxury, Performance and Premium Collections and increases the towing capacity to 3,500 pounds (1,587 kg).

For 2012, the Base suspension offers greater ride quality that maintains excellent handling characteristics, thanks to new upper front strut mounts, improved shock valve tuning, new bonded bushings for the front stabilizer bar and new twin-tube rear shocks that provide greater road isolation.

The Sport active suspension - standard on Performance and Premium Collections - is also improved for 2012, with new front upper strut mounts, new shock valving, bonded stabilizer bar bushings and revised calibrations for this continuously variable real-time damping suspension system. Electronically controlled dampers at each corner "read" the road constantly to make real-time adjustments within milliseconds. They deliver the just-right damper rate for all road conditions, for greater comfort and a greater feeling of control. This system also increases damping during aggressive handling maneuvers to reduce the roll velocity and pitch velocity of the vehicle for a more confident feel.