The nice thing about being able to afford the ML550 is the 382-horsepower V-8 under its hood. Calling this SUV "fast" is an understatement. Mercedes says it goes from zero to 60 mph in 5.6 seconds. That's muscle-car fast. This muscle SUV had me flooring it whenever I could to get the engine to come to life. Even so, I'm sure even my most enthusiastic driving didn't put the full power of the ML550 to the test.

There are shift paddles on the back of the steering wheel so drivers can select any of the automatic transmission's seven gears manually at any time. The location seems odd in that they're essentially hidden from view, but ergonomically they make a lot more sense than the funky column-mounted gear-selector stalk you use to move from Park to Neutral to Drive to Reverse. I'm not a huge fan of paddles if they don't do a better job of accelerating than just plain mashing the gas pedal, but I surprisingly found both methods of joyriding enjoyable in the M-Class.

The other big surprise was at the pump, where I realized I was getting more than 16 mpg during all this pedal-mashing and lots of stop-and-go rush hour traffic. I logged almost 1,000 miles during my long loan, and my gas mileage stayed at that 16-plus-mpg number. That's dead-on with the EPA's 13/18 mpg (city/highway) ratings. Sure, you're pumping premium into the ML, but these numbers are quite good for the class, and especially for this much power. On open highway trips of 50-plus miles, the trip computer had me in the low-20-mpg range.

Handling was superb. All models feature all-wheel drive, and the ML550 has 19-inch wheels and tires that contributed to an extremely comforting, planted feeling at all times. The M-Class also has an optional selectable suspension that moves between automatic, Sport and Comfort modes. Many other luxury cars on the market feature similar setups, but few work quite as transparently as the M-Class'. The Comfort setting did make the ride smoother on highways, turning this otherwise bruising SUV into a great cruiser. The wife almost enjoyed a long commute in bumper-to-bumper traffic because it was so comfortable. When you hit the off-ramp, though, you'll want it in Sport mode, as the suspension stiffens and turns the handling quotient up a bit. The bumps also make themselves well known in this setting.

I found myself in Comfort mode — why anyone would choose the default mode, I'm not sure — during long commutes and with passengers in the car. At all other times, I drove in Sport.

The one failing in the M-Class' performance repertoire is its braking — I'm not sure how you build such a powerful vehicle and don't give it the most responsive brakes possible. The 13-inch ventilated four-wheel disc brakes stopped the car, but the mushy brake pedal feel led to poor response at almost every stop sign, light or congested road. It usually takes a day or two to get the feel of the brakes in the car you're testing because every car brakes differently. After 10 days, though, I was still jerking passengers' heads as I rushed to avoid possible fender-benders at every turn. That's a feeling you don't want to have when piloting such an otherwise-fine performance machine.

The ML350 costs roughly $10,000 less than the ML550 and features a less intriguing 268-hp V-6 engine and 15/20 mpg mileage estimate. I'm not one to say go for broke, but it would take a lot for me to give up the V-8's power.