A slick navigation system
The head-up display is one of the coolest and most self-evidently useful bits of military technology to find its way into cars. They're not on every car yet, though, so there's still a pretty good chance you don't have one. Enter Navdy, which has been in the works for a while but is only now actually shipping to customers. It pairs with your phone to provide you with not just navigation, but also your music, speed, and incoming text/call info right in front of your face.