This post cracked me up. For several weeks I had wanted to post the same question, but I was too embarrassed to admit I could't figure out how to turn off a car.
I finally broke down and searched through the owner's manual, which lays out there various "states" of the systems and different ways to trigger them.
I now shut off the engine with the start/stop button, and then press the idrive power/volume button to shut off the systems.
it's all good.
