For Mazda, Linux is used in the infotainment system. There is an entire community built around tweaking that infotainment system, and somebody has bundled those into a package called Mazda All In One Tweaks. They've done some pretty impressive stuff, such as adding Android Auto support before Mazda officially did. https://github.com/Trevelopment/MZD-AIO/
Even more, the Mazda's UI (like many other car infotainment stacks) is actually written in JavaScript. The infotainment boots into Opera browser and renders whole UI as a webapp.
Otherwise it's a rather nicely designed system - using dbus for communication without too much of a wierd hacks.
On the one hand, MZD-AIO is very cool, and getting Android Auto on my 2015 Mazda 3 is so welcome.
On the other hand, with or without Android Auto, my infotainment is wildly unstable, very slow to start (and inconsistently so), and generally sluggish. Starting this spring, Android Auto often crashes out a few seconds in, or if I try to interact with anything (though that could be in part or in whole on the phone side - stock Google Pixel 3...)
Last I contributed to the the AIO Auto codebase, it did have quite a few race conditions and nasty hacks to make it working. So having it be unstable is not unsurprising. The SoC in the infotainment also isn't a beacon of speed.
Are you using the AIO Auto implementation or the official Mazda one?
Presumably you have to go to the dealership and pay them to install it? I couldn't find anything online (other an AIO) for getting it through official channels.
The kit requires replacing the USB hub and adding a new USB cable to the infotainment computer. The equipment itself costs about 150$ and plenty of people did the installation themselves (apparently the hardest part is to get the plastic off from dashboard between the screen and the USB ports to run the new cable).
