There are some stories floating around about CarPlay being run by, powered by, or something by QNX, BlackBerry's embedded operating system division. A better way to phrase it is that CarPlay "takes over the user experience" of in-vehicule infotainment systems running QNX. Here's the thing: Apple doesn't make or license embedded operating systems for smart cars just like they don't make or license embedded operating systems for TVs. They simply hook into what's already there, be it a Ferrari or a Panasonic, via CarPlay or Apple TV.
Sure, there are substantial differences. Hooking into TVs is unidirectional, has been done for decades, and currently benefits from the ubiquitous HDMI standard. Hooking into cars is bidirectional, relatively new, and there's no equivalent standard. Controlling an in-car display is also much more complicated, since they vary so much, requiring conduits for Siri, touch, and/or the various dash controls.
Given all that, when a car company partners with Apple, the QNX team (or maybe the embedded Android team or whomever runs the infotainment system) absolutely has to make sure everything that CarPlay needs is in place. That's why Apple works with them. Which is pretty much what they had to do in the past, albeit in a much simpler way, for the old iPod connectors program.
There's a huge advantage to this approach. If you have an iPhone, you get in, plug in, CarPlay comes up, and you go. If you don't have an iPhone, you get in and whatever infortainment experience the manufacturer has built-in comes up. Everyone is happy.
If Apple made the whole stack, it'd be different. Apple would either have to get the car company to agree to iPhone exclusivity — which seems highly unlikely — or the car company would have to get Apple to agree to build in support for Android, Windows Phone, BlackBerry, and feature phones — which seems downright unimaginable. In other words, no one would be happy.
That CarPlay would work this way has been obvious and apparent since its introduction back in June of 2013. That it's getting attention now is likely only because BlackBerry bought QNX a few years ago and linking competitors makes for sensational headlines. (Apple sources a lot of their device components from Samsung, so just wait until everyone re-remembers that!)
I looked for but couldn't find specific information on whether or not QNX is first, best, or simply getting the most attention as infortaiment software CarPlay takes over. There are other Microsoft, Android, and Linux based alternatives in the automotive and infotainment space as well. Either way, I have nothing but respect for QNX. It's an amazing real-time operating system that's proven itself on everything from automobiles to nuclear power plants to smartphones. Likewise, great work by anyone and everyone building the embedded systems that let CarPlay do what CarPlay does.
But really, what runs the infortainment system is about as relevant to a CarPlay user as what runs the smart TV interface is to an Apple TV user. That's its job.