Send directions to your Android phone from a desktop Google search
Once you have Google up on your browser, type in "Send directions." Type in the address of where you are heading to, and you can use the prompt in the upper right corner to select which of your Google-connected Android phones you want to send the directions to. On the bottom is a link that reads Send Directions to My Phone; click on that link and the directions are sent to the Google Maps app on the Android phone you've selected..
So once you are in the car, all you need to do is open Google Maps, click on "navigate" and turn-by-turn directions will begin. Keep in mind that this feature has just started rolling out for Android users, so it might not yet be available in your area.
source: +Google via Gizmodo