I found a workaround regarding the proper sorting of Spotify playlists in Apple Car Play, where there are no options to sort (by name or by date).
Apparently it always defaults to Custom sorting, which can ONLY be changed in the Spotify app in OSX (or windows ?). There you can manually sort the playlists panel (on your left) in the preffered order with drag & drop and this Custom sorting is saved in all of your spotify devices, including apple car play.
Hope that helps