CHELSEA, Mich. -- At the Chrysler vehicle research and testing facility in Chelsea, Mich., tortuous off-road driving courses incorporate virtually every type of natural obstacle one might encounter when steering a sport utility vehicle away from pavement.
There are big rocks and deep ruts to overcome, barricades of tree trunks to climb and steep inclines to scale, sandy dunes to plow and creek beds to ford, along with acres of tire-sucking mud to traverse.
One steep slope with granite slabs and boulder-spiked sluices even duplicates the Rubicon Trail, which stretches across California's Sierra Nevada Range as the most challenging four-wheeling trace on the continent.
Run through these courses and you can quickly determine how well a vehicle rigged for off-road travel handles the diverse traction challenges.
Run these courses in a four-wheeling edition of Commander, Jeep's big SUV with three rows of seats for a seven-passenger capacity, and this brawny wagon easily conquers all trail obstacles and builds driver confidence with a demonstration of its amazing off-road prowess.
Recently, we spent time at Chelsea running the off-road courses in current versions of Commander, which consist of three trim variations for 2008 issues and three powertrain options including a new 4.7-liter V8 and a hunker 5.7-liter HEMI V8.
The squared-off Commander looks like a fresh homage to Jeep classics like Wagoneer and Cherokee, although it's thoroughly modern in content.
Commander's 2008 models contain sophisticated electronic systems for safety, such as Hill Descent Control (HDC) and Hill Start Assist (HSA), all-speed traction control (ASTC) plus an electronic stability program (ESP).
And there are cool new gadgets available, like Sirius Backseat TV, a MyGIG multimedia kit using a 20-gigabyte hard drive for music and video storage, the iPod interface and ParkView, a rear-view camera.
Commander stands tall in the traditional two-box format of a wagon but with all sharp corners contoured and the horizontal lines chiseled and planed.
Wheel openings are cut in a trapezoidal design with wheels pinned near corners of the platform and front and rear overhangs crimped to make transitions easy on slopes.
There's no doubt it's a Jeep, however, as familiar Jeep design cues like the seven-slot grille and round headlamps are prominent on Commander's prow.
Yet Commander looks so square in style, with edgy angles scoring fascia and fenders, a flat hood and flanks, steep rake of the windshield, plus a roofline that's stepped higher in back to add headroom inside for backseat riders.
Commander's passenger compartment is a luxurious space containing three rows of seats arranged stadium-style, with each successive row rising higher than the row in front.
A bench on the second row splits in sections divided 40/20/40 percent, while the back bench separates 50/50.
Seatbacks on both second and third rows fold forward to form a flat floor and expand the cargo space.
At the rear of the cabin a top-hinged liftgate accesses the cargo bay.
And in the stepped-up ceiling, there are optional skylights packaged with a front-seat sunroof to bring more light into the compartment.
Commander's base unit for 2008 also shows an optional five-passenger cabin configuration with two rows of seats.
Chassis and hardware for Commander come from Jeep's flagship SUV Grand Cherokee, including powertrain options and choices for different four-wheel-drive (4WD) systems.
A unibody structural design creates a rigid container that resists flexing and twisting when set in motion on pavement or dirt and ultimately enhances the smooth-riding manners of Commander.
Precise rack and pinion steering brings quick-response turns and produces a tight turning diameter of only 38.7 feet for easy maneuvering.
And the independent suspension system, with short/long arms up front and a live axle in back braced by twin-tube shock absorbers, enables front wheels to move vertically high in order to step up and address off-road obstacles.
Commander offers two-wheel-drive (2WD) traction for the three different trim grades of Commander Sport, Commander Limited and deluxe Commander Overland.
For 4WD traction, Jeep adds options with three different systems -- Quadra-Trac I, Quadra-Trac II and Quadra-Drive II.
The Quadra-Trac I system has a single-speed transfer case for full-time all-wheel-drive (AWD) management and no levers to pull.
Quadra-Trac II contains a two-speed electronic transfer case for full-time 4WD operation and locked 4WD low range.
The ultimate system is automatic Quadra-Drive II with front and rear electronic limited slip differentials (ELSD) for infinite torque management at each of the four wheels plus an electronic stability program (ESP) for checking lateral slippage and a dynamic handling system (DHS) to decouple suspension stabilizer bars when not needed.
Quadra-Drive II also brings HDC and HSA for 2008.
For powertrains, Commander has three more choices.
In base issue Commander Sport stocks a 3.7-liter single-cam V6 which makes 210 hp at 5200 rpm with 235 lb-ft of torque at 4000 rpm. The V6 ties to a smooth-to-shift five-speed automatic transmission, the W5A580.
For upscale Commander Limited, the standard engine is new and strong -- a single-cam 4.7-liter V8 producing 305 hp at 5650 rpm and torque of 334 lb-ft at 3950 rpm.
With V8 engines, Jeep adds a different five-speed automatic shifter, the 545RFE which incorporates electronic range select (ERS) interactive shift controls.
Optional plant for Commander Limited is a 5.7-liter HEMI V8 screaming with 330 hp at 5000 rpm plus 375 lb-ft of torque at 4000 rpm.
And this HEMI comes with a multi-displacement system (MDS) which can switch seamlessly and transparently to fuel-saving four-cylinder mode when all of that horsepower is not needed for romping.
Top trim Commander Overland only carries the HEMI V8.
A 2WD Commander Sport with V6 power is the price-leader with the 2008 MSRP set at $27,415. Commander Limited with the 4.7-liter V8 lists for $36,305 in 2WD mode or $38,925 for 4WD. And ultimate Commander Overland with the HEMI V8 and Quadra-Drive II 4WD caps this series with a tag of $42,950.