Since the late 1970s BMW's renowned Motorsport GmbH division has been turning out ultra-performance "M" cars. While the best-known of these remains the M3 and M5 Sedans, the U.S-built Z4 roadster has spawned a pair of equally scintillating offspring: The M Coupe and M Roadster. With notable upgrades to their powertrains, performance, appearance and attitude, these two-seaters are fully capable of putting their performance levels and images up to such competitors as the Porsche Boxster S and Cayman S, Chevrolet Corvette, Honda S2000, Lotus Elise and Exige, Mercedes-Benz SLK55 AMG and Nissan 350Z in its Grand Touring iteration.