Wow, sounds like you've gotten to know the car pretty well!

For the drain issue, which I was having (the occasional Battery Drain message in iDrive when I start car), the dealer said they hook up the car for a day or so to a computer, and they have some way of knowing what's causing the drain (they didn't find anything). Not sure how you can do so yourself or if an indy shop can do that too.

PS Which battery did you pick and who coded it for you?

 

My battery was draining, it was the small handle/switch for the tailgate glass. Easy job if the handle isn't seized on to the wiper spindle but they often are. Mine started playing up when it was frosty conditions as the moisture in the switch froze and damaged the internals.