DSUB works with Android Auto (and *mostly* works with Google Driving Mode on phones). I use it all the time for that.
https://play.google.com/store/apps/details?id=github.daneren2005.dsub&hl=en_US&gl=US(google drive mode - it doesn't support Google Driving Mode's APIs for starting playback after browsing. You'll need to pick your songs and hit play in DSUB, then go back into Driving mode and it'll pick up).