mdosu wrote wow, generally, you would need to swap out an entire ECU and diff unit at a minimum, I don't think you can simply swap out your ECU. This would be very complex job. Think of the wiring headaches involved in doing it, and I have a feeling BMW may force you to electronically mate your new ECU to your current engine.
Just for a reference, my old Evo had a mechanical center diff, and to swap it out with an active electronic unit, you needed to do the ECU and the entire set of front, center, and rear diffs (of course this was a AWD car). And this is a unit that did not interact brakes into the system.
After reading this I feel like you are very confused. But maybe I am? Do you understand that MDM refers to a DSC program, and not a mechanical differential or any other mechanical part of the car? All M3s have the same differential, aside from the gear ratio which differs between DCT and 6MT.
OC3 wrote I just fact-checked "no iDrive = no MDM" issue with someone who has 2011.5 model w/ no iDrive, and he says his car goes into MDM mode when he pushes the M button and that, apparently, all models past 2011.5 have it.
Yep, that is absolutely true. That is what Frenchboy was referring to in his thread-reviving post. Notice, this thread is very old - far pre-dating any knowledge of the new simplified MDrive for 2011.5.