I'm really surprised that these car manufacturers aren't chomping at the bit to bring car play on board.
Most car manufacturers have really clumsy interfaces. Some examples are Ford, VW, Audi, Aston Martin, Toyota, Land rover & mercedes just can't seem to get it right.
They only really intuitive car interface i've seen is the BMW iDrive which many of the other german brands have tried to copy but don't quite hit the mark.
I understand not wanting to push customers into iPhone but i'm sure they could easily offer both options in the car.
I'm not a big fan of touch screens in cars though, find it very distracting and think the BMW dial approach is best and hopefully car play can be controlled this way as well.