BMW's telephone audio system is mono just like the navigation and TV function. BMW Bluetooth systems do not support A2DP, and if they did it would be in mono.

I was under the impression that the E60 5 Series was designed different with A2DP but I have not heard anyhting since the annoucement 2 years ago

http://digital-lifestyles.info/2005/...h-bmw-5-series