Yes and no.
AC or sets is hardly core car functionality. Likewise if the car were willing to give up the same info it makes available over the OBD port (things like speed, gas level, early warning indicators) Apple might be able to do interesting things with that.
There was a company, Automatic, that made a dongle that plugged into the ODB port and use that info for a variety of interesting purposes including
- allowing you to record everywhere you drove and how fuel-efficient you were
- noting if your car was starting to be less fuel efficient than usual
- warning you if you drove in various sub-optimal ways (aggressive starts or breaking)
- warning you of various "check engine" conditions
In principle Apple could do the same thing today (via an Apple dongle plugged into ODB), but it's obviously a better user experience if the car manufacturers just provide this same data to Apple via whatever connector already connects to their head unit/Car Play unit.
The real issue for the car companies is basically same as the cell companies -- they don't know how to provide a decent experience from what they have, but they can't stand the thought that someone else might generate user value from "their" data...
And they seem determined to handle this the same way as cell companies -- not by doing a better job, but being otal dicks who try to prevent anyone else from doing a better job. Hasn't worked out well for the cell companies...