1998 BMW Z3 M Roadster The Z3, from mild to wild. By Tony Swan, New Car Test Drive .com

Here's the latest chapter in the ongoing BMW Z3 story: It's called the M Roadster. And it's real speed reading.

First there was the Z3. It's gorgeous, but with just 138 horsepower from its 1.9-liter inline 4-cylinder engine, it's a bit too tepid for serious sports car enthusiasts.

BMW followed up last year with the Z3 2.8. Its 189-horsepower inline 6-cylinder engine pretty much silenced the power pundits, but it was overshadowed by the new Porsche Boxster.

Now comes the M Roadster, with raw performance that makes the Boxster look just a bit tame. In the BMW alphabet, M stands for Motorsports. The engines and suspensions are developed in a separate skunkworks that's also home for BMW's racing activities. The Z3 is assembled exclusively at BMW's new facility at Spartanburg, South Carolina, and the M Roadster is the first M model BMW has ever assembled outside of Germany.

The M power in this case is BMW's familiar 3.2-liter dual overhead cam 24-valve inline-6 tuned to the high levels of the M3 coupe and convertible. The result is 240 horsepower and 236 pound-feet of torque. With a curb weight of 3,084 pounds, this adds up to impressive acceleration: 0-to-60 mph in less than 5.5 seconds, 0-to-100 in less the 14 seconds. The C5 Corvette is quicker, but not by a whole bunch.

The basic Z3 starts at $29,995, the 2.8 at $36,470, the M Roadster from $42,770.