The release of the Google Maps iOS app has been a blessing this holiday season for iPhone users. Siri, the digital assistant built-in the iPhone 4S and iPhone 5, automatically syncs direction requests with Apple Maps. Thankfully, JailBreakNation has discovered a way that allows users to get directions on Google Maps with Siri.
Simply activate Siri and request directions as you normally would but add "via transit." For example, you might say: "Give me directions to the nearest Apple Store via transit."
Instead of providing directions with Apple Maps, Siri will display a list of routing apps, including Google Maps. Tap the icon for Google Maps and voilà, you're on your way.