The wheel was invented more than 5,000 years ago and it has brought some awesome vehicles our way. But this invention isn't over and done with yet! Take a tour of some of the most unique and fascinating vehicles around. See how military unmanned ground vehicles tackle rough terrain and keep soldiers safe. Find out how the fastest electric racing cars work. Think a car can't handle street driving one minute and tackling sand dunes the next? The high-performance Zarooq Sandracer can! See the limitless possibilities of wheeled vehicles! Part of the Cool Rides series.