I own a Ford and a BMW, both with CarPlay. The BMW is flawless. The Ford just refuses to connect about 10% of the time and requires the infotainment system to be rebooted. It also occasionally connects but leaves audio coming out of the phone speaker. So yes, implementations vary.

I have a Ford that after 13 years is reaching the point where I'm considering replacing it.

Their homemade infotainment system prior to CarPlay was awful, and has an overflow error which hits me about once every 6 months which requires pulling the fuse to hard reset it. As far as I can tell they keep adding new songs to a stack, and never flush it so at some point you'll reach the end of a song and it won't play any more. Once you reached that you can only use the phone function, attempts to use music result in you getting your Bluetooth connection terminated.