My E70 was at the dealer the last 2 weeks for repairs. I had a 3 series as a loaner. In the X, you can either shift into park or just hit the start/stop button to kill the engine and it automatically shifts into park. In the 3 series, if you're in drive and hit the start/stop button, it stays in drive and you can't remove the key. Your issue might have something to do with a sensor not detecting the car has shifted into park. Just a guess.

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E70 X5 3.0si Space Grey

E36 Z3 2.5i Roadster, Sterling Gray Metallic