(FORTUNE Magazine) – Sitting in front of my house was $70,000 worth of the fastest car Mercedes ever made. Trouble was, I couldn't move it. Two inches of snow and ice in the driveway had made the car immobile.

My experience with the CLK55 AMG is a reminder of the tradeoffs you make when you drive automotive exotica. On the highway, the four-seat coupe goes like a rocket and handles curves like a sports car, but it jars the kidneys when riding over expansion joints. On snow, the combination of the big engine and wide, slick tires means that the wheels spin futilely when the throttle is applied. Computer aids like traction control and automatic skid control can't cope with spinning wheels, and mistakenly apply the brakes when you don't need them.

Winter driving aside, the CLK55 is for buyers who value speed, exclusivity (only 1,000 are available this year), and anonymity. Except for the model name and a discrete "AMG" label on the trunk (identifying Mercedes' in-house performance-engineering outfit), the car is easily mistaken for the standard CLK430 that costs 20 grand less. The AMG upgrade means the CLK55 can zip to 60 mph in under five seconds and rapidly approach the electronically limited top speed of 155 mph.

Comparison shoppers will probably also consider a Porsche 911 Carrera or a Jaguar XK8, two cars that present more distinctive profiles but are less practical. Neither has a habitable rear seat or a decent-sized trunk. The Mercedes is more flexible: It can carry four adults with relative ease and hold loads of luggage. But if you insist on driving in winter, install all-season tires--or get an all-wheel-drive Mercedes ML320 to park next to it in your garage.

--ALEX TAYLOR III