I have experienced some problems, especially on hot summer days when the car has been under the sun, with my ignition switch. When I tried to turn the key in order to start the car, it was kid of stuck and required some unusual effort. Also, in some occasions the key remained in position 3 and I had to manually turn it back in order to avoid damages to the starter. So, a couple of days ago I dipped my key in ATF oil and inserted it in the ignition. I then started the car and turned the key several times. The ignition key now turns smoothly. I repeated the same procedure with the door and trunk locks. The cylinders seem to require some oil from time to time.
I will buy a new cylinder in order to have it handly, just in case. It's only $48.70 at bimmerzone.
Hope this helps.