Since the release of CarPlay in 2014, the only navigational option on CarPlay has been Apple's own Maps app. In any case, the beta phase isn't expected to last too long as both CarPlay and Google Maps are stable platforms and it should be a matter of them either of them is made compatible for both. One limitation is that you can't use Siri to control Google Maps.
iOS 12 is available to download right now for a score of iPhone and iPad models.
Once done, go to Settings General CarPlay on your iPhone and select your vehicle.
Google's Waze navigation app does not yet support CarPlay, but its development team are working to implement it, according to the report. User no doubt will be glad to make the transition to Google Maps that offers a much more comprehensive coverage. When you land, simply refer to Google Maps and navigate to your saved locations. Our Apple Maps custom points of interest are sparse in comparison. You might expect that update to arrive soon, and more third-party turn-by-turn apps to add support as well, so you'll have more alternatives to Apple Maps to help you get where you want to be. It's versatile. Apple Maps on a computer is strictly tied to a pre-loaded Mac app (remember that?).
With such improvements in the works, it will be interesting to see whether or not Apple improves its Maps enough to prevent users from replacing it with other navigation options such as Google Maps and Waze.