You may be surprised to know that Waze has not been available on Android Auto. They started rolling out a public beta in April and finally, now people are getting access to the app. The Waze Auto app basically works the same as the regular Android app.
Waze sent out an email to beta testers with some extra information. Waze is not available on Audi and Mercedes-Benz vehicles. There are a few bugs with the release as well. Voice commands are not supported yet, there are issues with zoom on high-res displays, and more.
If you’d like to try out Waze on Android Auto, you can sign up right here. You will get an email when the beta is ready for you.