For one thing, the ML320 suspension is all independent, rather than employing traditional live axles at both ends, a plus in flexibility and in ride quality.

For another, instead of conventional locking differentials, which dictate uniform power delivery whether there's traction or not, the M-Class differentials are governed by Mercedes' 4-wheel electronic traction system (4ETS), originally introduced in Mercedes sedans and adapted for four-wheel drive. Electronically linked to the vehicle's antilock brake sensors, the system is designed to detect slippage at one or more wheels. When a wheel begins to spin, the system automatically applies braking to that wheel, thus sending engine torque only to the wheels that are still pulling.

In ordinary operation, torque is split evenly between front and rear wheels. But as long as one wheel has grip the ML320 can keep moving. This is particularly useful when only one wheel has firm contact with the earth. The only other SUV we've seen that's capable of this feat is the AM General Hummer, the warlord of sport-utilities. But even though the Hummer is still the ultimate off-roader, it's exactly as handy on the street as your average armored personnel carrier.

On the street, the ML320's mass is exceptionally well controlled. It changes directions well for a sport-utility vehicle--no drama, no peril--and the superb brake system delivers stopping distances worthy of a sport sedan. In fact, it's hard to believe this vehicle is as heavy as it is. It's even harder to believe it's a truck.

If there's any weak point on the dynamic scorecard it's the steering, which is short on feedback when the wheel is pointed straight ahead--no tactile information for the driver. But it doesn't take much steering input for the numbness to dissipate, and compared to most other sport-utilities, the ML320's steering is well above average. Call it a B on a report card otherwise festooned with As.