 A robotic startup in Florida claims to have built the fastest running robot in the world. Outrunner, a six-legged machine that can run up to 45 miles per hour on a treadmill and 25 miles per hour outdoors. The company behind Outrunner is raising $150,000 on Kickstarter, and the creators say they'll stage a race for the world's fastest robots if they make that goal. So who would win? MIT set a speed record in 1989 with a robot known only as the Planar Biped. It reached speeds of 13.1 miles per hour, but only when running in circles while tethered to a pole. That record held for 23 years, until it was broken by Cheetah, a robot built by Boston Dynamics, the company that was recently acquired by Google. Cheetah can hit 28.3 miles per hour on a treadmill, faster than Olympic runner Usain Bolt. It needs a power tether, however. The unleashed version of the Cheetah, called Wildcat, can only run up to 16 miles per hour. That still beats MIT's current four-legged robot, also named Cheetah, which clocks in at 13.7 miles per hour when indoors and tethered. Elsewhere in quadrupeds, the Italian Institute of Technology is working on the Hi-Q, a versatile, animal-like robot that can squat, rear up, and jump. It's not that fast, though. It only runs up to 4.4 miles per hour. Over in humanoids, the Toyota Partner robot can hit 4.3 miles per hour, beating Honda's Asimo, which can run up to 4 miles per hour. Meanwhile, there are experiments with robots that run on, quote, wags, wheel legs or wing legs that imitate bipedal running with spokes. And some of those can reach up to 6 miles per hour. Right now, it looks like OutRunner may have a lock on the land speed record, at least outdoors. But with all these creative approaches, we'll have to see a race before we know for sure.