Kia Motors Corp. says two drivers set a new Guinness World Record the lowest fuel consumption in a hybrid gasoline vehicle, while driving a 2011 Kia Optima Hybrid sedan through the 48 contiguous states.

Wayne Gerdes from Wadsworth, Ill., and Chris Bernius from New York drove the factory-standard car 7,899 miles while recording an average fuel economy of 64.55 miles per gallon. The result beat the car's official EPA highway fuel-economy rating by 61%. The result in part shows that drivers can often boost their vehicles' fuel...