If you have a high end German car out of warranty and you aren't a multi-millionaire you should check out Leo and Tweaks.
Tweaks actually does diagnosis and repair as opposed to sequentially replacing items until the car works again (ie std bmw, porsche dealer tactics....)
Greg
The owner there is Leo. I'd have to recommend him as he fixed an electrical issue that my BMW dealer could not fix and gave up on. I was nervous trying a non dealer garage, but he dealt with the issue and didn't try to over sell or cross sell me on anything. So for this I'd have to recommend him.