The current system for rating tracks while connected to Android Auto does not result in an effective way of managing a library.
Currently, Plexamp rates as follows:
★ = 5 star rating
☆ = 0 star rating
/☆ = unrated
Plex does not offer a way for search for tracks with a 0 star rating (the ☆ option in the AA app), making this option effective useless. I would prefer the ratings be 5★, 3★, 1★, and ☆ = unrated; this would make the UX clear as to what you are rating a track, and only adds a single tap to the interaction.
I just tried filtering tracks by < 1★, and you are correct, that does show tracks rated with ☆, so this is working as intended.
But now I’m thinking this reduces the rating system down to a / rating, which is inconsistent with Plex’s star rating system. I guess the solution would be to make a new smart playlist for tracks played in the last day, rated 5★ and adjust from there.
I understand that managing media is wholly secondary to focusing while driving, but since the functionality is already in the app, there is a chance to make it more useful.