With its unmistakable HUMMER design and a compact, go-anywhererndriving ethic, the HUMMER HX concept challenges the hierarchy of therntrail. HUMMER displayed the nimble, reconfigurable off-roader at thern2008 North American International Auto Show.

More compact than arnHUMMER H3 - 81 inches (2,057 mm) wide, with a 103-inch wheelbasern(2,616-mm) - the HX concept is an open-air, two-door off-road vehiclernthat packs the off-road acumen for which HUMMER has become legendary,rnalong with an easily convertible body that acclimates to varied trailrnconditions, cargo needs or passenger whims. Its design is based on thernideas developed by a trio of young designers who are new to the HUMMERrnstudio.

"The HX is HUMMER's vision of an agile, trail-ready,rnopen-air vehicle that fits the lifestyles of everyone who needs orrnwants to drive off road," said Martin Walsh, HUMMER general manager.rn"Of course, it carries exceptional off-road capability and therndistinctive styling for which all HUMMERs are known."

The HXrnoffers an open-air driving experience via a pair of removable roofrnpanels above the driver and front passenger, and a modular, removablernrear roof assembly. With the roof panels and roof assembly removed, thernHX is transformed into a true convertible.

Easy removal of thernroof panels and rear-roof assembly enables quick conversion from arnclosed vehicle to an open one. The HX also was designed with severalrnroof assemblies, allowing this versatile vehicle to be configured as anrnSUT (with the roof assembly removed), a stylish slant-back or arntraditional, wagon-like design that offers a bit more cargo space.

• Removablerndoors - easily removable pins in the exposed hinges allow the doors tornbe removed quickly - an appreciated feature of many serious off-roadersrn
• Removable fender flares - attached with quarter-turnrnquick-release fasteners, the composite fender flares can be quicklyrnremoved for additional trail/rock clearance, or if the flare is damagedrnduring off-road driving

"The modular design of the roofrnand removable body panels mark an evolution of HUMMER's designrnaesthetic," said Carl Zipfel, director of design. "These featuresrndemonstrate a deeper understanding of enthusiast desires when it comesrnto off-road driving - and the slant-back design gives the HX a look allrnits own."

Purposeful exterior

The designrnof the HX was driven by input from three young designers who were newrnto GM and the HUMMER design studio. As part of their "initiation," theyrnwere charged with developing concept drawings for a smaller, youthfulrnHUMMER and the HX is a direct result of their creativity. The HXrnconcept is based on one of the designers' original illustrations, butrnincorporates the best ideas and elements from the other designs.

"HUMMERrnappeals to young people globally and served as a perfect firstrnassignment for our newest talent," said Ed Welburn, vice president,rnGlobal Design. "Today's graduates from top design schools are ready tornhit the ground running. The HUMMER design challenge gave our newestrndesigners an opportunity to sprint."

Inside and out, the HXrncarries a purposeful aesthetic that, from initial sketches to finalizedrnclay models, was refined in only six months.

"This is the HUMMERrndesign language stripped down to its essence," said David Rojas,rncreative designer. "The HX has an aggressive appearance and greatrnproportions, with beauty lying in its functional austerity."

Onrnthe exterior, the lightweight theme is evidenced in the appearance ofrnexposed, billet aluminum suspension components that featurernCNC-machined lightening relieves, as well as clean, unadorned bodyworkrnand minimal trim. The lightweight theme is taken to its extreme whenrnthe roof panels, roof assembly, fender flares and doors are removed.

ClassicrnHUMMER design cues make the HX instantly recognizable, including thernround headlamps located in square housings, an upright windshieldrnprofile, minimal overhangs, hood vents and prominent air intakes. Thernair intakes are functional and feed a V-6 engine beneath the hood,rnwhile the hood vents are active - they articulate to allow hotrnunderhood air to escape.

And while the headlamps and grille arernclearly HUMMER cues, they've evolved on the HX with a "chopped circle"rnmotif. The grille slots and headlamps, as well as elements on therninterior, have the appearance of circles or ovals that have beenrnclipped at the top and bottom, creating a unique appearance that speaksrnto the vehicle's purposeful aesthetic.

"The 'cut-off' circles suggest larger, heavy-duty components that were trimmed to fit the compact HX," said Rojas.

Andrnwhile it is unadorned by extraneous embellishments, the HX's exteriorrnis nonetheless outfitted with features that speak to HUMMER's legacy ofrntechnology and innovation, including HID headlamps with focusing ringsrnthat adjust automatically when they're turned on - much like the lensrnof an auto-focus SLR-type camera. LED technology is used for the frontrnturn signal lamps and taillamps.

Aeronautically inspired interior

Fromrnaircraft-inspired seats to integrated, off-road-ready tools, the HUMMERrnHX's interior has a beauty that lies in its purposeful intent. It wasrninspired by the functional and lightweight elements found in aircraft.

"Aeronauticalrnparts are designed to be both lightweight and strong, and that is thernfeeling exuded by the HX's cabin," said Stuart Norris, interior designrnmanager. "There isn't superfluous trim or decoration - it is arnpurposeful design that conveys beauty through strength."

Reinforcingrnthe stripped-to-the-essence feel, the exterior's matte olive colorrncarries over onto the interior's largely sheet metal-covered panels.rnThe color is accented with pressed or extruded aluminum components,rnsuch as the handles, switches and other necessary parts.

Furtheringrnthe aeronautical influence is the instrument panel, which uses anrnexposed, extruded aluminum cross-vehicle beam as its foundation. On thernbeam, the instrument cluster and other vital controls are mounted; andrnit also features a unique, removal top cover that provides significantrnstorage capability.

"The instrument panel is a styling element ofrnthe HX, and the removal of the top cover reveals a secondary designrnthat enhances the vehicle's core design ethic," said Norris. "With therntop cover removed, the interior conveys even more of a basic essence -rnand the structure beneath the cover is beautiful to those whornappreciate finely crafted metal."

A rubberized floor andrnballistic nylon-material covering on the instrument panel and otherrninterior components reinforces the functional aesthetic.

Seating and console details

Likernaircraft seats, the HX's seats are constructed on a lightweightrnframework with minimal components that feature lightening holes andrnstrength-enhancing cross braces or triangulations. They are mounted onrnexposed, aircraft-style tracks and trimmed with a weather-resistantrnneoprene material.

The HX seats four, with a pair of bucket-typernseats in the second row. The rear seats mimic the front seats' designrnand can be removed to generate more cargo room. All the seats feature arnfour-point, racing-style safety harness.

The inner seat track onrnboth front seats is located beneath the outer edges of a prominentrncenter console. The console offers exceptional storage capability andrnhouses a unique shifter that mounts low and out of the way when thernvehicle is parked - also hiding from sight the engine starter button.rnIt has a spring-loaded cover that pops up when the driver is ready tornselect a gear.

The console also houses a resting place forrnphones, MP3 player and iPods or iPhones. In fact, there is nornconventional radio in the HX, only integrated speakers. Passengers plugrnin an iPod, or similar device, to a USB connector to play music in thernHX.

"From the console to the cargo area behind the seats, therernare simply untold storage possibilities within the HX," said Norris.rn"It's like a four-wheel backpack that's already fitted with thernnecessities."

Gauges and tools

Thern"cut-off circles" motif of the exterior is seen even more so on thernHX's interior, as the gauge cluster, instrument panel vents and evenrnthe steering wheel carry the design element.

A three-elementrngauge cluster - each of the three instrument "pods" carries the cut-offrncircle design - delivers crucial driver information in either a highwayrnor off-road mode. This conceptual reconfigurable gauge layout uses LCDrnscreens with multiple layouts, including a navigation system. The navrnsystem features GPS and compass information; and is designed to uploadrntrail information before setting off on an excursion.

The centerrngauge pod houses a speedometer and tachometer, but changes to a wheelrnangle indicator when the transmission is in the low position. Thisrnoff-road mode changeover from the highway mode gives the driverrninformation that is more pertinent to the driver conditions. The trailrnview of a camera mounted in the rear-view mirror can be displayed onrnthe instrument panel, too.

The off-road mode features of therninstrument panel comprise the virtual tools of the HX, while others arernmounted for physical use, including a folding shovel, flashlight andrnfirst-aid kit. They all carry the "clipped circle" design motif foundrnthroughout the vehicle.

Ready for rocks, trails and more

Withrnits compact dimensions, almost no overhangs and grippy 35-inch tires,rnthe HX is ready for all terrains. Like all HUMMER production models,rnthe HX has sturdy, body-on-frame construction, onto which is mountedrnfront and rear independent suspensions.

The front suspensionrnfeatures an electronic-disconnecting stabilizer bar for enhancedrnmaneuverability when driving off road, and the rear suspension isrnlocated with Computer Numerical Controlled (CNC)-machined, billetrntrailing arms. Heavy-duty shocks with piggyback reservoirs wererncustom-made for the HX by renowned racing shock manufacturer Fox; onernis mounted at each wheel position.

A full-time 4WD system pullsrnthe HX over, through and around off-road obstacles. It transfers torquernto the front and rear axles, each of which is equipped with a lockingrndifferential. The torque meets the trail via custom 35-inch-tallrnoff-road tires that are mounted on a set of custom, bead-lock-stylernwheels that have a two-tone appearance; dark-painted wheel centersrncomplemented by silver-anodized outer rims.

A complete underbodyrnarmor kit, including a front skid plate, powetrain protection and more,rnprotects the HX from wayward rocks and other potentially damagingrnobjects. A power-operated winch is located in the front bumper, and thernHX has recovery hooks mounted on the front and rear bumpers, just inrncase its help is required for wrangling others out of unfortunaternoff-road situations.

Motivation for the HX comes from an E85rnFlexFuel 3.6L SIDI V-6 that is backed by a six-speed automaticrntransmission. The transmission is teamed with the 4WD system to offerrnexceptional low-speed traction and crawling capability. Four-wheel-discrnbrakes provide confident stopping power.

SPECIFICATIONS

• Body style / driveline: two-door, four-seat open-top, four wheel-drive
• Construction: welded steel frame, electro galvanized steel
• Engine type: 3.6L V-6 VVT (variable valve timing) with spark-ignition, direct injection
• Displacement (cu in / cc): 217 / 3564
• Bore & stroke (in / mm): 3.70 x 3.37 / 94 x 85.6
• Block material: sand-cast aluminum with cast-in bore liners
• Cylinder head material: cast aluminum
• Valvetrain: DOHC, 4 valves per cylinder, variable valve timing (VVT)
• Fuel delivery: direct high-pressure fuel injection
• Compression ratio: 11.3:1
• Horsepower (hp / kW @ rpm): 304 / 227 @ 6300 rpm (est)
• Torque (lb.-ft. / Nm @ rpm): 273 / 370 @ 5200 rpm (est)
• Fuel Type: unleaded regular or E85 ethanol
• Transmission: Hydra-Matic 6L50 six-speed electronically control automatic transmission
• Suspension:
  • front: independent SLA, custom Fox Racing coil-over shocks; 2-in shocks, 2.5-in springs
  • rear: semi-trailing link, custom Fox Racing coil-over shocks; 2-in shocks, 2.5-in springs
• Wheel travel (in / mm):
  • front: 9 / 228
  • rear: 11/ 279
• Brakes: four-wheel disc; Brembo 6-piston calipers (front); Brembo 4-piston calipers (rear)
• Rotor diameter x thickness (in / mm): 15 x 1.25 / 381 x 31.75
• Wheel size & type: 20-inch x 9-inch
• Tires: 35-inch custom Bridgestone Dueler
• Wheelbase (in / mm): 103 / 2616
• Overall length: 171 / 4343
• Overall width (in / mm): 81 / 2057
• Overall height (in / mm): 72 / 1829
• Track (in / mm): 67 / 1702 (front); 68 / 1727 (rear)
• Minimum ground clearance front (in / mm): 13 / 320
• Approach angle (degrees): 56
• Departure angle (degrees): 51
• Breakover angle (degrees): 25
• Grade capability (percent): 60
• Side slope capability (percent): 40
• Water fording capability (in / mm): 24 / 610 (at 5 mph)
• Seating capacity: 4