You already know that you can use Siri to ask for directions. You might say, “Give me directions to 1 Infinite Loop in Cupertino, California,” or you might say “Take me home” when you’re out and about.
But there are a few other things you can say to Siri whilst your iOS device is helping you navigate, and you might not know about these options.
Ask Siri, “Are we there yet?”—or similar, less obnoxious incarnations of that query—and you’ll get an update on your estimated time of arrival. You can get more specific, too. Ask, “When is my next turn,” and Siri will give you the number of minutes until you should encounter it.
Tank running low? Ask Siri where the nearest gas station is, and you’ll get suggestions for fill-up spots along your current route. If you tap one, though, you’ll cancel your current navigation in lieu of the new destination instead.
Mac OS X Hints