No idea about now, but a few years ago BMW had a disastrous batch of onboard computers, which weren't cheap to replace at all.

My stepfather had one with such a problem, and stopped buying BMWs after being a loyal customer for 30 years - his BMW 2002 (model, not year http://en.wikipedia.org/wiki/BMW_New_Class) he could service for himself, while the newer models he can't even touch.

Edit: example complaint http://www.complaintsboard.com/complaints/bmw-c127.html