Apple Car play apps
QUOTE:
Apple’s built-in apps:
Phone (Favorites, Recents, Contacts, Keypad, Voicemail)
Music (iTunes Radio including Beats 1, Music library including Apple Music, iTunes Match [iOS 9.3 includes For You and New from Apple Music)
Maps (Search, POI’s, Navigation [Nearby with iOS 9.3])
Messages (Create, read, reply over Siri)
Now Playing (this will show audio content from any iPhone app similar to iOS’s Control Center)
Podcasts (if you don’t use this app, you can disable it in the Restriction section of the iPhone settings app and it will disappear from CarPlay the next time you connect your iPhone)
iBooks (with iOS 8.4 for playing audiobooks)
END QUOTE
According to this article from 9to5mac you can only use aplles built apps with car play. Other Apps won't work! And this was the answer I needed.
Bypaolo