I'm fairly certain CarPlay doesn't support the Google Maps app - it uses Apple's Map app, which is still fairly bad.
In an ideal world, to be agnostic to whatever device you have - iPhone/Android/Windows/BBY, Mazda could have spent time and energy on an application that does app screencasting via Bluetooth or USB. So instead of trying to build partnerships and make custom app integrations, the job would be in supporting as many devices as possible and basically writing pixel and touch zone transformations.
A considerable side effect would be a result of such a wide variety of screen sizes - how do you determine the size of the infotainment screen. That'll be tough and whatever you choose you'll get black bars on the top and bottom on most devices except one or two they were optimized for.
Mazda picked the "other" agnostic approach to just ignore everyone else and go with Naviextras. It does make sense once you think about it. Even if all the car manufacturers supported a thunderbolt and USB 3.0 dock system, so that any tablet can double as your navigation system - how about connecting your phone? Which screen do the phone contacts show up? How do you make a universal physical controller?
Until Microsoft/Google/Apple play nice, we won't see much change in the strategy the manufacturers are taking.