Heya!
I'm currently running version 905 of PA, and great news for the tabbed view in Android Auto!
I think, though, that the Android Auto experience can be revised as following:
1) If I get this correctly, Poweramp shows 4 tabs: Library, Playlist, Album and Folders hierarchy. Which is great, it takes all the 4 available slots but:
There will be rendundancy between elements in library view and tabs indicators so, e.g. if I choose to show playlists in library view, I'll get a tab and a tile for it
Removing one item from library view will also remove the tab
So I think that
Tabs should be user-configurable
Poweramp should avoid showing an item in library view if it's shown as a tab
2) Action buttons in playback view do not take advantage of all the slots available. A total of 9 actions can be configured on Android Auto (one of which shows the secondary actions) and right now PA shows 5 primary actions and 2 secondary actions. Allow me to suggest some actions that can be ported to Android Auto:
Fast forward-Fast rewind
Buttons for like/dislike
Button to add a bookmark
I don't know if those are technically possible:
Button to add to a playlist: once pressed it will bring up the list of playlists for adding the track and destroys view afterward
Button to go to artist: similar to number but goes to artist view
Button to go to album: as above