VANCE, Ala. - The first rule about driving the Mercedes-Benz ML320 down a steep slope is not one that fills you with confidence.
Remember, advises your Mercedes-Benz U.S. International Inc. guide as the vehicle appears to roll over the edge of a cliff: 'Don't touch the brake pedal.'
The nose of the shiny new ML320 is hanging in the air, the red Alabama soil falling away in a 70-degree drop.
It is part of a muddy, slippery, rock-impeded off-road course Mercedes has built behind its new Alabama assembly plant to train its dealers.
Suddenly, a blip of the throttle nudges the front wheels over the edge, which looks increasingly like the first drop of a roller-coaster ride. But with the M class' transfer case locked into low range, the 3.2-liter V-6 engine acts as a brake. The vehicle catches itself and, like a donkey on a canyon trail, eases down the slope in a confidence-inspiring creep.
Some unconventional thinking helped create the M class' unique four-wheel-drive system. Even though the ML320 has the moxie to tackle steep trails and ford streams, officials at the plant realize that few owners will ever push their vehicle anywhere near its limits. 'Most sport-utility owners don't know when to lock a differential,' says Stephen Cannon, regional marketing manager for Mercedes-Benz U.S. International Inc.
So Mercedes engineers poured their efforts into making the M class' four-wheel-drive system as invisible as possible to the driver. In most conditions, the traction system engages without any help from the driver. When the going gets really tough, the driver needs only to stop, shift to neutral and press a button on the instrument panel to engage the low range, which is effective up to about 55 mph.
While the assembly plant has spent the summer slowly cranking up production, Mercedes has been using its off-road course to train dealers.
Dealers put the M class through its paces there, side by side with the vehicle's chief competitors -the Ford Explorer and Jeep Grand Cherokee. The course is designed to exploit the benefits of the ML320's four-wheel independent suspension and unique 4wd system.
Whereas the M class calmly steps over a section of massive, staggered railroad ties, both the Explorer and Grand Cherokee pitch their passengers from side to side, a consequence of their solid axles.
At another section of the course, two wheels at a time are lifted off the ground, totally removed from traction. The vehicle's torque transfer system pulls it through with only slight hesitation. But once the Explorer and Grand Cherokee get hung up, the driver is forced to rock each vehicle backward and build up some momentum to clear the obstacle.
ON THE ROAD
On road, the M class is pure Mercedes-Benz. The seats are well bolstered and supportive. The dash layout is typically Mercedes, with gauges clustered in three circles.
Cruising on Interstate 95, which runs past the front of the Mercedes plant and has been dubbed by locals as the Alabama-bahn, the M class strongly accelerates to legal, and extra-legal, freeway speeds.
The ride is smooth and carlike, with lane changes executed crisply and without a lot of the body roll noticeable on some other sport-utilities.