Originally Posted by bmw1racer
^ I've never seen it on any of my cars, but I'm guessing that maybe there's some kind of malfunction in the side mirror defroster...?
If it were to get too hot, that kind of discoloration would occur....?
Thanks for the reply. That is kind of where I'm going, I noticed the issue after a visit to a highly trusted detail shop. Like many shops, they use warm or hot water to clean cars. I'm looking for an explanation that lines up with experience from other owners... I think I will cross post to the 3 series forums (we could use a general BMW forum for all models).