2008 Mercedes-Benz GL-Class Road Tests

Large and luxurious, the GL-Class full-size SUV is built in the United States alongside the M-Class mid-size SUV and the R-Class touring wagon. The GL is designed to appeal to Mercedes-Benz sedan owners who want the off-road, seven-passenger, and 7500-pound towing capabilities that come with a full-size SUV along with the luxury and safety features they have in their other Mercedes vehicles.

While their names sound similar, don't confuse the new GL-Class with the venerable G-Class or Gelandewagen. The GL shares nothing in common with the utilitarian G-Class. The GL-Class shares its basic platform with the ML-Class and R-Class.

The Mercedes-Benz GL-Class is large and capable off road yet feels surprisingly car-like on the road. That car-like feeling comes in part because it is built around a unibody architecture instead of traditional body-on-frame construction. Mercedes says the GL is strong enough to tow a 30-foot boat, a trailer carrying three horses, or a large travel trailer, but verify tongue weights and ratings before making decisions. All GL-Class models come with a seven-speed automatic transmission and four-wheel drive. All seat up to seven people.

All GL-Class offerings come with a seven-speed automatic transmission, the 4MATIC all-wheel-drive system, and the Airmatic air suspension system. It comes with seating for seven and with a third row that powers up or down at the touch of a button.

The GL320 CDI and GL450 models are similarly equipped, although not all options are available on both models. All models have a power driver's seat, heated power mirrors, heated windshield washer nozzles/lines/reservoir, reading lamps, burl walnut trim, and so forth.

Options include Distronic radar-controlled cruise control; a rear-seat entertainment system with two screens; Keyless Go, which allows the car to be started as long as the key is inside the vehicle and locked/unlocked with touching the key; Parktronic, which uses sonar to detect obstacles near the vehicle; a power rear tailgate; harman/kardon Logic 7 surround sound system; and DVD-based navigation.

The GL550 comes with full leather, Parktronic, rear-view camera, premium audio, adaptive bi-xenon headlamps, infrared-reflective glass, heated steering wheel, heated front and middle-row seats, and Adaptive Damping Suspension.

Safety features that come standard include eight airbags, including side airbags for all four outboard first and second-row seating positions as well as side curtain airbags that protect occupants in all three rows. It comes with active front head restraints, LATCH tethers for child safety seats, and three-point safety belts for all seating positions; make sure everyone in the vehicle always wears those seat belts because they're your first line of defense in a crash. Active safety features (to help you avoid a crash) include an Electronic Stability Program, anti-lock brakes with Brake Assist Plus, and four-wheel electronic traction control. Optional safety features include Parktronic and a rear-view camera, each of which can help alert the driver obstacles or people, including children, behind the vehicle. The last time we checked, the GL-Class did not come with child locks on the rear side doors.

Unique to the GL550 is a deeper, more aggressive front-end treatment, including a larger three-pointed star that does not accommodate Distronic cruise control. It also features larger fender flares to cover the massive tires and dual-split exhaust outlets.

Seen in profile, the nicely raked windshield and bulging wheel arches over large wheels (18-inch and larger) help balance what is basically a tall and long vehicle. But even being tall and long, the GL doesn't look as bulky as, say, the Chevy Tahoe and GMC Yukon. And even with the squared-off rear edge of its D-pillar, the GL doesn't look as boxy as the Jeep Commander.

Viewed from the rear, the GL offers a formidable stance. It's tall and wide, with a large rear hatch opening and large tail lights, all sitting above a substantial skid plate bracketed on either side by large, rectangular exhaust pipes.

Compared to the ML, the GL is nearly a foot longer overall and an inch wider in track (the axle width including wheels), though it is less than half an inch wider overall and not quite an inch taller. Despite their similar styling, the Mercedes SUVs share only their front doors; otherwise, each has unique sheet metal.

As large as the GL may appear, it's two inches shorter than the R-Class touring wagon, which also has three rows of seating, though with room for only six occupants.

The GL is built using unibody construction rather than the body-on-frame design that full-size pickups and SUVs traditionally use. Mercedes notes that because of this architecture, the GL-Class is 300-600 pounds lighter than its full-size competitors. To make sure the GL class is strong enough, 60 percent of the vehicle structure is made from special high-strength steel.

Cargo space also benefits. With all seats in their upright position, there's still 14 cubic feet of storage between the third-row seatbacks and the closed rear hatch door. A power folding feature for the third row is standard equipment on the GL with controls near the rear hatch and next to the right-side second-row passenger's seat. Power down those third-row seats, and cargo capacity expands to 43.8 cubic feet. Fold down the 60/40-split second row seats and the GL provides as much as 83.3 cubic feet for cargo. There's also room under the cargo floor for a full-size spare tire.

The interior layout is familiar to Mercedes drivers, with either faux or real leather trim for the seats (Mercedes notes that not all luxury car buyers want real leather seating surfaces), wood trim and metal rings around gauges, air vents, and cup holders.

The second-row seats provide ample legroom. When occupied by only two people, the back of the center section can be folded down as an armrest and storage tray.

We climbed into the third row and found room for two adults to ride back there, each in a separate seat. The room is enhanced by foot wells for your feet so you don't sit with your knees at chest level, and even the third-row seats are thickly padded to provide comfort. Fears of claustrophobia back there evaporate quickly thanks to the sunroof that extends over the third row.

The GL can be equipped with a 440-watt, 11-speaker harman/kardon Logic 7 sound system, with Sirius Satellite Radio and with a DVD video entertainment system with screens mounted in the rear of both front-seat headrests and with a 6CD changer.

The GL550 can accelerate from 0 to 60 miles per hour in six seconds or less. Its 382-hp V8 with four valves per cylinder, is part of a new family of V8 engines from Mercedes-Benz, all designed with a broad torque spectrum for hauling around 2.5 to 3.5 tons of truck.

The GL450 is more than adequate with its 335-hp V8 if towing or speed contests aren't on your agenda. Apart from the 21-inch wheels and more aggressive bodywork, a GL450 can be optioned to match a GL550 in features. Indeed, for poor road areas, severe winter climes that frequently require snow chains, or those inclined to use the low-range gear in the Off-Road package, the GL450 is the better choice.

The GL320 CDI delivers more than adequate thrust from its little V6 turbodiesel engine. In fact, it boasts more torque than the GL550's hefty V8, torque being that force that gets you going and powers you up hills. The GL320 offers slightly superior fuel economy to that of the GL550. If high-altitude driving is routine, it's worth noting the turbocharged diesel engine loses far less of its power than the normally aspirated gasoline engines as the air gets thinner. The diesel is flexible, providing maximum torque from 2800 rpm all the way up to 4800, and horsepower that pulls past 6,000 rpm.

The seven-speed automatic transmission helps keep the GL-Class engines operating in the sweet part of a power band.

The four-wheel-drive system, called 4MATIC, features front, center and rear differentials. Quite sophisticated, 4MATIC is designed to maintain mobility even when only wheel has traction. In normal driving, the system distributes power equally to front and rear wheels. The system includes DSR, a sort of cruise control for regulating downhill speed, and Hill-Start Assist, which keeps the GL from rolling backward when launched after being stopped on uphill slope. 4MATIC also adjusts anti-lock brake controls to provide quicker stops on slippery and unpaved surfaces, an important benefit many vehicles with ABS do not offer.

Airmatic is an air suspension system that uses air bladders instead of coil springs to adjust ride height by as much as three inches as well as ride firmness and body control parameters, so the driver can select from comfort and more aggressively sporty settings. The system automatically lowers the vehicle to enhance handling and aerodynamic efficiency at speeds of 77 mph or higher. Adaptive Damping II, which provides electronic control and driver-selection of shock settings for the best combination of ride comfort and handling response, is standard on the 550, optional on the 450, and not available on the 320.

Those serious about venturing far from pavement can opt for a special off-road package on the GL320 and 450 that includes special wheels and tires, a two-speed transfer case, locking center and rear differentials, adaptive damping and with ground clearance height-adjustment options to allow as much as 12.4 inches of ground clearance compared to the standard highest clearance of about 10 inches.

We did our driving on freeways in and out of San Francisco's airport and on roads through Napa Valley wine country. Steering feedback was consistent, brakes (14-inches in diameter on the front wheels and 13 inches on the rear) were responsive and consistently predictable and the GL offered nice balanced dynamic capabilities when hustled through the curves on the narrow, hilly roads that wind through the vine-covered hillsides. The fat 21-inch tires contribute commendable grip, and like the majority of wide, low-profile tires, follow pavement grooves, give sharper impact sensations, and can not use tire chains.

NewCarTestDrive.com contributor Larry Edsall filed this report from California's Napa Valley.