Travel across difficult terrain usually involves a lot of compromise. Tracks will get you where you need to go, but they're slow whenever you're covering open ground. DARPA, however, doesn't think you should have to make that choice. It's working with Carnegie Mellon University on Reconfigurable Wheel-Track technology that converts wheels from tracks to tires (and vice versa) in the middle of a drive. As you can see in the clip below, the change takes just two seconds -- you could drive off the road and up a hillside without skipping a beat.