The car audio is connected via BT. Some devices with newer BT version cannot connect to the S2. What I recommend you is, install only the android base (don't flash the sfos zip) and boot into it. Try to connect android to your car audio system. If it connects and works, then probably there is a problem with the BT settings in my port. If it doesn't work, then obviously cannot be easily fixed on the Sailfish Os side either because the problem is on the android side.