From
1addicts.com
* More muscular appearance than standard 1-series
* Trapezoid grille flanked by two intakes to allow extra brake cooling
* Six piston brakes
* High performance intercooler
* Sportier looking headlights than standard 1-series
* Small lip spoilers above brake duct inlets to provide extra air flow and downforce
* The front wings of the car are massaged slightly to accomodate the wider track. Rear end is also wider.
* Standard 18" 5-spoke wheels with optional 18" Competition wheels (18" will be the optimium wheel size for the M1)
* Signature M side vent
* Broader wheel arches to accomodate larger track
* "Ducktail" CSL style rear trunk (integrated spoiler)
* Rear valance/diffuser area takes its direction from the standard 135i but with open ducts for aerodynamic purpose
* Signature M quad exhaust pipes
* Reinforced carbon fiber roof
Source:
http://www.1addicts.com/forums/showthread.php?t=348217
This is supposed to be pretty close:
