Not long ago I have seen some threads talking about porting android auto to an android head unit. The android head unit, mostly integrate car radio, stereo, GPS navigation, camera and others.So in my view, it's good enough for many scenario and requirements.

One of the reasons for installing the android auto, that the android HU manufacturers don't want to provide full mirroring of smartphones, or an internal Android OS. And the Android Auto won't do that, you can even use Pandora or Spotify on it.In fact, it’s easily to be sued by distracted driving deaths and maimings.