I was really excited to see the release note mentioning improved voice commands for Android Auto, but unfortunately voice commands still won't work for me.
I did some additional testing, and it seems when Google Maps is the main app open in Android Auto, Google Assistant will not work at all. As soon as you switch to a different app, in my case Spotify, tapping the Assistant icon works. I have microphone permissions enabled for every Google app including Maps, so it should be working. I recorded some video of this behavior, and can send it in a DM to someone on the team, just let me know.
I also took logs for Google, Google Maps, Google Play Services, and Android Auto to hopefully help fix this issue.
I'm putting the logs in a separate notes page because they're too long to send here:
Google Logs: https://monogr.ph/673e5bebf3126cdba5570c3e
Google Maps Logs: https://monogr.ph/673e5c45f3126cdba5590c3e
Google Play Services Logs: https://monogr.ph/673e5c66f3126cdba55b0c3e
Android Auto Logs: https://monogr.ph/673e5c93f3126cdba55d0c3e
Please let me know if I can help troubleshoot this issue in anyway, it's the one thing that's really been bothering me. Thanks!
EDIT: It also seems the Microphone doesn't work in the Google Maps even when not connected to Android Auto.