Port Charlotte man claims device can boost car mileage to 500 mpgGREG MARTIN, Charlotte Sun Updated — 10:35 p.m., October 9, 2007 If John Weston of Port Charlotte can get investors to take his gas-saving invention to the global automotive market, it just might solve the problems of smog, global warming and the high cost of foreign oil. John Weston stands next to his 1992 Geo Storm, which is equipped with his invention dubbed the Air Vapor Flow System. He claims the car can run 14 miles on 4 ounces of fuel, which would equate to more than 400 miles...