After showing off Waze Android Auto integration at Google I/O 2016 (yes, over a year ago), the integration has finally launched — in beta, at least. Android Police reports that after an April beta sign-up, real, working code has finally gone out to beta testers.
Right now this is for cars with Android Auto working on their head units and is not intended for Android Auto the app version on the phone. But regardless it is finally a move in this direction.
See https://arstechnica.com/gadgets/2017/06/waze-beta-finally-launches-for-android-auto/ 
Android Auto finally gets Waze integration—in beta, at least
One year later, Google’s other navigation app comes to its in-car interface.