If you're keeping tabs on the automobile industry you'll know it's changing radically. Ownership is becoming less and less interesting to new drivers and this is causing fits within the industry:
Articles like this are just trying to glamorize the millennial generation as free from the societal norms of their parents. Every generation had something similar to rebel against normalcy. If the millennials are not buying cars they must have lots of money in their savings account, or maybe they are spending it all on tattoos.
Everybody kept saying Apple was going to make a TV set themselves. And maybe they were doing R&D in that area but I think they realized it makes more sense to stick with making a box that can plug into ANY brand TV and make it awesome (and maybe even offer a subscription TV service). Why try to become an expert in TV hardware manufacturing when what you really want to do is revolutionize the interface? Yes, Apple likes the idea of making all parts themselves to control the entire experience but why add the expense and learning curve of a whole new industry that's not really part of who you are as a company? TV's aren't a broken concept the interface is and you don't need a new TV to make a great interface. (Plus people don't want to upgrade their TV every few years.)
I think the same is going to be true for this automotive project. Obviously a total guess on my part but wouldn't it make more sense to create modular tech that can go into any car and can be upgraded whenever you want without having to replace your whole vehicle? I've had a few vehicles that I loved but HATED the tech and there was no easy way to upgrade/replace it. To solve this problem Apple would need to bring in experts from the automotive industry to make sure they are considering all aspects in inventing a new universally connectable piece of hardware (and, I'm sure, other engineering considerations).
Ultimately I don't see enough of a reason why would Apple want to learn how to manufacture cars (quite literally trying to reinvent the wheel) when they can focus instead on what they do best: create an innovative piece of tech with a great UI to solve a problem in a clean, simple way. So going forward car manufacturers can do what they do best (make well engineered vehicles from their years of experience) and leave the tech (which by and large they suck at) to a third-party making it replaceable, upgradable, and more future-proof.
my 2 cents