Slightly off topic, but I finally figured out how to get Apple Music surround sound to play into my Audi‘s Bang and Olufsens audio system. The key was NOT to use the wonderful wireless Airplay interface, but to run a USB cable out of the phone into the cars USB port that feeds the multi media system. just drove home from work listening to Becks Sea Change. Ear candy!
So your car only creates fake surround through the USB port and not through wireless Airplay. Interesting.