The M version of a BMW is always the high-performance version of that same series (M3, M5, M6). The M3 is a 3 series with upgraded suspension, engine, brakes, transmission, etc.
The M5 (2000-2003) has a 400 hp V8 engine and does 0-60 in about 4.7 seconds. That's Ferrari fast! Not bad for a 4 door luxury sedan!
Doug
(BMW fanatic)