All the predictions out there are 100% wrong, inaccurate, and lazy. Apple will NOT release a "car" as you currently know it.
It will be software on wheels; it will be an entertainment system, work/social hub, and by accident happen to take you places. It won't have a steering wheel. It won't need maintenance or a dealership network like traditional auto makers. It won't need insurance or even a drivers' license to own, because you won't be operating it. There's a good chance you won't even be able to OWN it. Those future profit margins exist is the future automatous taxi fleet, the entertainment system, and the ecosystem that exists inside and around the car as a product.
There's so much potential here if you just forget what you already know. Yes, Apple will partner with some existing manufacture to produce the car (like they do with existing products). No, it won't be based on any existing platform, it will be built from the ground up, both hardware and software, and be totally unlike anything that currently exists.
Apple is laser focused on one thing: the end user experience -- take the user somewhere, with as little input as possible, and wow the consumer with something so profound they didn't even know they wanted it; instantly make everything before look so old and clunky you will never look back.
Think back to UX 101: All user input is error.