Is this possible?

My mum's Beemer has a function whereby when you put it in reverse, the nearside wing mirror tilts down so you can see the curb so you don't scrape your alloys against it.

Would it be possible to wire the mirror up to do the same when you put it in reverse, or have a separate button that does the same without having to faff around with the wing mirror control every time?
 
I think it should be possible if you're good at electronics.

Probably need to use a relay, take the power from the rear reverse light as a trigger and take a feed from the electric mirror joystick to sort out only moving the mirror down. Not sure how you set it up so it returns to the position it was in.

At least that's how you'd do it in old cars, not sure if the CANBUS controls mirrors though which would make it a PITA!