Playing Spotify music in my car

[m-r-g]

I am unable to play my Spotify Premium from my iPhone 4 in my car. My car plays my music from a usb port. My friend's Spotify account works in it, but whenever i put my iphone in, it won't play anything. It says no music data is found. Why is this/ can I fix it so I can play music in my car?

[bchworth]

Its because you music application has no music. I have this issue. Your stereo ony reads music from your music application, nothing else. But when you start playing another application it takes over the audio out through USB.

Just just download some music into your music App and you will be fine. =P