Are you able to update any firmware within the cars audio system head unit? It may be that this new 5.0 update isn't compatible with some cars radios. I have seen similar posts by others with many different kinds of cars. Some can update their radio's software/firmware via a download and then installation via USB stick or SD card.
No, there is no firmware update available for the audio system. The audio system does support AVRCP 1.0 and 1.3, it appears that the update broke the 1.3 functionality with my car, the 1.0 functionality is still there. I spend a couple of hours a day commuting, and this loss of functionality is pretty aggravating.