[doughboy]

The seat / mirrors have effectively 3 memories:

Memory 1 seat button
Memory 2 seat button
Current position (not in M1 or M2)

And each key will also contain its own version of these 3 items along with aircon, audio, idrive settings etc

The idea is each driver (with their own key) has a full set of seat memory positions available to them.

The 'return to last position' only works when a different driver (key) opens the car relative to the key used when it was last locked. So if your other driver locks the car with their key with the seats in either M1, M2 or whatever, when you open the car with YOUR key the seat/mirrors will move to whatever positions (M1, M2, or whatever) you had them in when YOU last locked the car.

Each key only 'saves' its settings when the car is locked with that key so you have to be careful that you don't, for example, swap over driving with your other key holder without locking the car first with your key, otherwise they will jump in with their key, then when they lock the car all your settings will be saved on their key losing all their settings.

It crap really as most people share a car using the same key IMO.

As said, you can also select one of your M1 or M2 positions (using seat buttons) when opening the door and the seat will move to that before you get in.