https://www.theverge.com/2018/9/18/17875256/apple-ios-12-carplay-google-maps-waze-support-third-party-navigation

With iOS 12, Apple added support for third-party mapping services, namely Google Maps, to its CarPlay service, a much-needed feature that’s been a long time coming. That means, starting today, you no longer have to solely use Apple Maps when connecting your iPhone to your car’s infotainment and navigation center.

With Google Maps version 5.0, the update for which should be available for iOS users right now, you’ll get the ability to sync Google Maps navigation to your vehicle’s built-in display. You unfortunately cannot use Siri to control Google’s app, but it does come with built-in voice control that involves tapping a button to activate. (Taking your hands off the steering wheel is not recommended... but hey, it beats using your phone while driving, which is illegal and also definitely not recommended.)