I recently started using Android Auto in my car and I'm not sure if it's just me or if some people have found a way to break spotify in general, but when I use voice commands to try and play one of my Spotify Daily Mixes, it will instead search all public playlists and play one of those instead.
Saying "Play Daily Mix 1" or "Play Daily Mix 1 on Spotify" Spotify will search through public playlists and play a playlist named "Daily Mix 1" instead of my personal Daily Mix 1 playlist.
I tried asking for Daily Mix 3 and it started playing a public playlist called "Daily Mix Three". Before I had a car with Android Auto, I just used a bluetooth head unit in my car and Google assistant was able to control spotify and actually play my Daily Mixes perfectly fine using the same voice command. Not sure if this an issue with Android Auto, an issue with Spotify or if people on Spotify have some how managed to break the thing by naming their playlists the same as Spotify generated ones.