Noise after turning car off and opening door

Diversion

That's correct! It's the electronic motor for the steering lock! I hear it on mine everytime I turn the car off as well.. To prove it, your steering wheel siezes up without even turning it like a conventional style wheel lock system. Another thing you can do is turn left or right hard on the wheel (or try to) and turn the car on, the wheel is immediately freed up (unlocked).