OZARK, Ark. -- The Pig Trail Scenic Byway, a twisty ribbon of pavement cut through granite ramparts of the scenic Boston Mountains in northwest Arkansas, becomes our tight-wound track to test the road-hugging manners for a made-in-America edition of the new GL Class of sport-utility vehicles from Mercedes-Benz of Germany.
This 2007 wagon -- GL450 -- drives and rides like a luxurious Mercedes sedan and feels as comfortable. Yet it also provides a surprising amount of cabin space with three rows of seats for up to seven passengers plus cargo room in the back bay along with the go-anywhere attributes of a rugged four-wheel-drive (4WD) SUV.
It's the first full-size SUV for Mercedes, a crossover wagon rigged on a stiff unibody structure and it comes together at a Mercedes assembly plant in Tuscaloosa, Ala., which also produces the mid-size M Class SUV as well as the large-scale R Class sport tourer wagon.
GL450 resembles no other vehicle in the extensive Benz fleet.
It's large -- the wheelbase stretches to ten feet and it's a foot longer than M Class wagons, with the roof topping out several inches taller.
It's bold in style, with the traditional two-box format of a SUV molded into a windswept wedge marked by a slinky prow, racked-back windshield and roll-top roofline.
It has lots of doors.
There's a pair of portals on each flank below what looks like one extremely long window stretching from the windshield clear back to the tail.
Also, a top-hinged liftgate at the rear swings high for access into the cargo bay.
Focal point is the dominant nose grille scored by two chrome-clad fins and a large round star medallion of Mercedes-Benz.
Front corners house big lamp clusters of projector-beam headlights comprising individual chrome tubes.
On the list of optional gear, Mercedes adds bi-xenon headlamps that swivel in concert with the angle of the steering wheel to keep a light shining on the vehicle's forward path through a bend in the road.
GL450 rolls on five dual-spoke aluminum alloy wheels capped by 18-inch 265/60 all-season tires with a four-wheel independent suspension, height-adjustable Airmatic springing and optional adaptive damping system which raises the chassis ground clearance to 12 inches.
A new scheme for the seven-seat cabin creates a first-class cabin, as appropriate for a Mercedes, with soft vinyl or leather covering seats and appointments of the quality and caliber of a deluxe full-size luxury car.
The driver sits in a form-fitting bucket rigged with power-controlled contours and faces a four-spoke steering wheel with multi-function tabs and aluminum trim.
Ahead is an arching cowl covering the instrument cluster with twin-tube binnacles housing black-faced analog gauges for the speedometer and tachometer.
A console contains the Thermatic dual-zone climate control system and component audio equipment.
Second-row seats hold two or three riders. With only two in place, the back of the center section folds down to add an armrest and storage bin.
The third row consists of two separate seats with convenient foot wells in place and a standard sunroof overhead to add an air of spaciousness.
Backs of the rear seats tip forward via power toggles in the cargo bay and fold flat to extend the load floor.
With third-row seats down, the cargo bay offers 43.8 cubic feet of room. Fold down second-row seatbacks as well and the bay expands to 83.3 cubic feet.
Nomenclature for all Mercedes vehicles consist of alphanumeric designations, with the class size defined by alphabetical letters and the engine volume expressed in liters and translated into three digits.
Thus, the GL450 takes its name from the GL Class of full-size SUVs and its 4.5-liter V8 engine turns into the numbers 450.
The twin-cam V8 runs to 335 hp at 6000 rpm with 339 lb-ft of torque spread from 2700 to 4750 rpm.
That's enough torque to raise the towing capacity to 7500 pound.
Transmission is the impressive Mercedes seven-speed 7G-tronic TouchShift automatic, which operates with a stubby stalk protruding from the right side of the steering column. To select a gear, you raise the stalk one notch for reverse, lower it one click down for drive or depress a button on the stalk's cap to park.
While driving, you may leave the stalk in full automatic mode or play the TouchShift buttons -- positioned on the back side of the steering wheel's cross bar -- to switch gears. To-and-fro movements of the TouchShift buttons step up or down the gear ladder one notch at a time with the control of a manual stick.
The full-time 4WD device aboard GL450 uses three open differentials -- front, rear and center.
The center differential controls wheel speed up front and enables the forward rollers to turn at a faster rate than the rear ones during turning maneuvers. Likewise, the fore and aft differentials allow outboard wheels to spin faster than inboard wheels in a curve.
Then Mercedes adds a four-wheel adaptation of the electronic traction control system dubbed 4ETS. Wheel sensors determine when a single wheel may slip on a slick surface and the device then brakes the slipping wheel and transfers engine torque to the other wheels to maintain forward progress.
Also aboard is the alphabet soup of computerized vehicle controls -- anti-lock brake system (ABS) with brake assist (BA), electronic stability control (ESP), hill-start assist (HSA) and downhill speed regulation (DSR).
And Mercedes provides roll-over sensors, curtain-style air bags for all tiers of seats, and a tire pressure monitoring system (TPMS).
On the list of optional equipment is a rear seat video entertainment system, Harman/Kardon audio system with six-disc CD changer, hands-free communication system, triple-zone interior climate controls, off-road gear adding two locking differentials and underbody skid plates, a power liftgate, Keyless Go entry device, Parktronic distance sensors, the bi-xenon curve-illuminating headlamps, and a DVD-based navigation system plus satellite radio service via the Sirius network.
2007 Mercedes-Benz MSRP begins at $54,900.