re: What car head units allow connection to apps on phones?

Yeah I'm replying to myself again, but I learned last night you can control apps via Bluetooth. Not full functionality like switching between playlists or stations on Pandora/Spotify, but I had a quick stop to make on my way home. After that I connected BT for the first time, and it immediately started playing Spotify, which was what I was listening to before I got out. And there were forward and back arrows on the screen. I flipped around through the playlist and it was a fast response. Another feature I didn't know about when I got it.