Motor Trend: BMW M Roadster vs. Mercedes-Benz SLK32 AMG

Roadster. That fundamental expression of top-down motoring, which combines two seats with an engine in the front and drive at the rear. The word conjures sunny summer drives to no place in particular-when the route taken has little to do with arriving in the least amount of time and more to do with appreciating the journey, the road, and the car.

Two of the most rapid roadsters at the pinnacle of the art are BMW's $45,990 M Roadster and the $54,900 Mercedes-Benz SLK32 AMG, which is new for '02. Both reflect each company's convertible motoring roots and philosophy, while each has been breathed on by its in-house racebred engineering divisions endowing it with heightened capability, rarity, and higher prices than its more common Z3 and SLK counterpart. While much attention is focused on both cars' high-output engines making them the quickest production cars from their makers, considerable work is also done to suspension and braking systems to match.

Since its debut in '98, BMW's Z3 has been admired for its design and kinematic qualities. When the highly anticipated BMW M3 arrived in late '01, it was a forgone conclusion that the M Roadster would soon benefit from the M3's thoroughbred 3.2L M S54 inline-six. Due to the unique intake and exhaust packaging constraints of the Roadster, it produces 315 hp rather than the M3's 333. On the other hand, the new engine still delivers 75 hp more than the 2000 M Roadster at 97.0 hp/L, and enthusiasts in the U.S. would finally get the same version of the convertible enjoyed by our counterparts in Europe.

From the stronger cast-iron (versus aluminum) engine block to the unique cylinder head, the 7600-rpm S54 engine shares little with other BMW sixes. Hardware aside, the M Roadster's engine elicits illicit behavior. When a skilled driver deactivates the electronic dynamic stability-control system and only his organic-based gray-matter restraint system remains, either great or terrible things follow. So powerful is the engine and so immediate are its responses to driver input that quick hands and feet are a prerequisite to driving the M Roadster (without the electronic governess overseeing his technique). With just 9.9 lb of car being propelled by each horsepower, the best 0-60-mph time is 4.74 sec-that is, of course, if you nail the launch with only a hint of wheelspin and never bang the rev limiter, which is reached with lightning speed in each of the five-speed manual's gears.

Topping the entire field in our M versus AMG comparison with a 67.40-mph slalom speed, the M Roaster is one of the most demandingly agile cars we've tested. Despite its wide tires and wider-than-stock rear track, the short-wheelbased car requires nerves of steel and an unerring readiness to counteract oversteer in a nanosecond. Brakes, too, are world-class, and their 12-in.-plus dimensions halt the car with a best-of-test 114-ft. Surely, this is a dedicatedly engineered car built to reward a well-trained enthusiast.