Interesting, I was thinking of posting this exact same thing in the Canadian SE thread.
Mine does this as well. Almost sounds like it's going to stall, but it has not done so yet. Noticeably worse the colder it is out. RPM drops as low as about 500 and then picks right up again.
I also garage mine, but it still gets down into the -20s C. I have a BMW charger and use it occasionally but not regularly. Even after being fully charged the car behaves the same on a cold start.
Since the car runs fine otherwise I figured I would take a video of it and just show the dealer next time I'm in for scheduled maintenance. Don't want to leave the car overnight for them to try and reproduce it.
My last 2011 335 with the N55 (no PPK or PE) did not do this. Since yours does it as well I'm guessing it is related to the PPK. I'll post a link in the other thread to this one. Would like to see if anyone else with the SEs are experiencing this in our Canadian winter.......
Last edited by Kernel Kurtz; 12-27-2012 at 12:33 PM.