The number by itself meant nothing except that it's compared to other M3s. The CSL had 215 rear wheel kw. A standard M3 has 195 and there was a freak with 200 (but different muffler). All measured on the same dyno. An extra 15-20kw means the claim of BMW of the amount of HP a CSL has over a standard M3 is correct. What is converts to in flywheel power is anyone's guess.