On my BMW forum, a guy connected an apple airport express to his car, then fed it into a digital to analog converter, then to his jl audio MS8 processor to get lossless audio streaming music over 3g from spotify (320bps) through WiFi/airplay via his iPhone.

For this to work for android, I would need to simultaneously pull data through 3g/4g via spotify and send it via WiFi/airplay to the airport express.

Here is a link to the thread:

Is there a way to do this through android via airplay, or using another audio hotspot type device and app? How would you guys do it?