The top of the line variant for the E24 BMW 6 Series in North America and Japan was the M6. The first generation of a BMW Motorsport tuned 6 Series, this new model was known as the M635CSi in most parts of the world, yet in Japan and North America, the model was dubbed the M6. M6 models were fitted with the detuned BMW S38B35 straight six engine, down to 256hp due to the addition of catalytic converters. This engine sent power to the rear wheels via a 5 speed manual gearbox. Visual changes for the the M6 included a larger front air dam, a lip spoiler on the trunk, and special BBS wheels. The M6 name wouldn't be used again until 2006 for the E63 BMW M6.