By default, Siri uses Apple’s Maps app when you ask her for directions. She can also use Google Maps, according to JBN.
To ask Siri for Google Maps directions, add the words “via transit” to your search. By doing so, the voice assistant will continue to open Apple Maps. However, she will also provide a link for Google Maps.
Click “Route” and your journey with Google Maps can begin.
For more information on Google Maps’ return to iOS see MapsOpener Jailbreak Tweak Makes Google Maps The Default Maps App, Apple Execs ‘Seething’ Over iOS 6 Maps Debacle, Google Maps Approval, and Google Maps In The App Store, Say What?