an American inventor, John Kanzius has created a method of "burning" saltwater, and a Japanese company is attempting to use his discovery, and claim they can run a car 50 miles per hour, for 5 hours on a tank of water. The Japanese group is hoping to adapt it to plain water,to reduce the clorine gas bi-product, and have stated unfiltered tap water has worked.
http://auto.howstuffworks.com/salt-water-fuel.htm