So I have a Telsa and it's the no.1 thing I hate about an amazing car. No Car play.
However: It already has:
Apple Music
Amazon Music
Spotify,
Tidal
YouTube music
Audible.
Disney+
Netflix
Other Video sources.
Phone, Message, Calender, Siri all work pretty well and some are integrated in the the screen - Tap to read out a message for example.
Tesla maps is now very good, and accessible from iPhone. You can ping an address to the car etc. It's so integrated that it's actually better than most other maps for a car. We have overlaid weather coming so you know if it's going rain etc on a journey.
And my new favourite thing: If you enter a stupid average speed zone... it shows you, current speed, max speed AND current average speed in case you speed up or slow down.
But are GM going to remotely do all that? Nope... they'll stick a crappy chip in there - Tesla has a decent AMD chip running it all. And it'll be as bad as VW entertainment v1. And they'll make you pay for their music I bet and various other things.
Luckily GM cars are crap.