Guinness World Records has now confirmed that a team of Duke University undergraduates have designed and built the most fuel-efficient vehicle prototype in history: a hydrogen fuel cell car that gets the equivalent of 14,573 miles per gallon. Duke Electric Vehicles (DEV’s) record-breaking run took place on Saturday, July 21 at Galot Motorsports in Benson, North Carolina. DEV, bested the old record set by ETH Zurich, which stood for 13 years.