2012 Mercedes-Benz M-Class Driving Impressions

The new engine is exceptionally smooth, while being powerful at 302 horsepower. It's aluminum, a narrow 60-degree V6, while most V engines are 90 degrees. The acceleration is excellent, you don't need more than this; engine is mated to a mechanically sweet new 7-speed automatic transmission.

Driving casually, the transmission is so smooth you forget it's there. The transmission is less sweet in manual mode, where it gets disobedient. It refuses to short-shift, upshift with moderate throttle at low rpm, or when the throttle is backed off.

The ride is smooth like the acceleration. We tried and tried, on Montana back roads including gravel, to find a spot the suspension couldn't handle, to no avail. The ride of the ML350 is solid, steady and comfortable in every situation we could find.

The ML350 doesn't like fast or quick cornering, though. Despite its new active rear anti-roll bar, part of the Dynamic Handling Package that our ML350 came with, also including active damping, air suspension, and 20-inch wheels with all-season tires. We pitched the ML350 into some twisties, and it responded with insecurity and reluctance to track true.

Maybe it's the new active electro-mechanical steering, and not the suspension or the $5150 worth of dynamic handling. The active rear anti-roll bar is split in the middle, and adjusts according to the needs of separate rear wheels; theoretically it eliminates body roll, but you won't hear us say that.

All ML350s are 4MATIC, or all-wheel drive (another thing you didn't get in 1998 for $54,824 of today's dollars). The sophisticated system stays at 50/50 on dry pavement, but can put 100 percent of the torque to one wheel, if necessary. With three wheels in mud, one on dry land, the Benz should drive right out.

We weren't able to test that, but we got great seat time off-road, and we were pretty much dazzled by the ML350's performance on Montana gravel and dirt roads. We wanted to drive it like a rally car, but the ESP wouldn't allow it. It was highly intrusive, shutting down the throttle at the mere hint of a slide.

The pre-tensioning seatbelts became a drag, too. We were hardly sliding at all, and the car kept shouting: We're gonna crash, we're gonna crash! So the belts kept strangling us at the chest.

It was amazing how the chassis smoothed out the bumps, whether in Comfort mode, or Sport mode with raised air suspension in the Dynamic Handling option. We found a rocky and rutty fire trail, and the big Benz just laughed.

We locked the brakes to test them on the gravel, and the stops were quick, true and drama-free with ABS, even at 50 mph. We ran hard for the final few miles on twisty downhill pavement, and the brakes smelled hot but didn't fade.

Our ML350 had the Driver Assistance Package, which includes a Active Blind Spot Assist that like all of them was flawed by false alarms, and Active Lane Keeping Assist, which keeps you from drifting across lanes or off the edge of the road, by vibrating the steering wheel and applying the brakes selectively to one side of the car to correct the motion. It too was flawed by over-reaction. True, if you're falling asleep and drift toward the edge of the road it might save your life; but the rest of the time the problem is it keeps trying to save you before you fall out of the boat.

But you don't have to pay extra just to be warned. Standard safety equipment includes ATTENTION ASSIST (their caps). There's an icon of a coffee cup that lights up while a message suggests you get off the road because you're weaving. Sensors measure “erratic steering corrections.” Those sensors are tough. If you weave just once you're marked as a possible drunk or dozer. And guaranteed, you will weave more than once, trying to work all the stuff on the console with the display screen and that mouse-like thing that they all claim isn't distracting, for example while tuning, searching, selecting and inputting any of things you might do using the COMAND System that comes with the Premium 1 package.

Driving the diesel-powered ML350 BlueTEC version revealed it has everything in common with the regular ML350 except the engine, which makes it feel like it has nothing in common. Before you go ML350 shopping, know your needs. We'd say that towing is the only reason to buy the diesel, good as it is. It only gets 3 miles per gallon more than the gas engine, costs $1500 more (which isn't much for 3 mpg). But it gives up excitement.

Basically, everything under the hood and in the cabin just happens slower with the BlueTEC, and makes the vehicle feel less nimble. The ride is as smooth, but the acceleration isn't. Redline is only 4200 rpm instead of 6200, but the powerband is so broad and there's so much torque (455 foot-pounds at 1600-2400 rpm) that the transmission could be a 3-speed and still work. For some reason, the transmission sometimes surged during slow shifts with the diesel engine.

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