I've been a Tesla owner for a couple of years and a Mac user for decades. The Tesla boards are all abuzz over this, too. What's not being talked about in this thread are comments by Elon Musk a week or so ago in an earnings call:
"I do have a secret weapon on the demand side that will probably start to deploy later this year for demand generation. Well see how that goes. It isnt totally necessary but I think and it could be pretty interesting, I could [indiscernible] dealers."
There's speculation on the Tesla boards that the secret weapon is a partnership with Apple. Possibly one in which Apple harmonizes all of the Model S's functions on the 17" display. From CarPlay to navigation and autopilot UI, Apple would do a great job improving the already great user experience.
This would certainly increase exposure for Tesla, presumably increasing demand. Furthermore, because this comment was in the context of countering automobile dealer associations' attempts to block Tesla direct sales, it's interesting to note that having Apple as a partner could make part of every Apple store a Tesla showcase, either through a Tesla mockup in-store or even Tesla demonstrations to interested people. They're not demo-ing the car, per se, just the Apple experience in the car. This could skirt the requirements that Tesla only operate through franchised dealers in those states that are still clinging to that model of car sales. The increase in exposure for Tesla would be enormous.
All in all, I don't think Apple is going to make a car. I think they're going to push CarPlay and their UI brilliance into as many automotive lines as they can, now that the human/car interface is becoming so much more audiovisual than ever before, beginning with Tesla.
Thanks for pointing that up.