WASHINGTON, D.C. – Natural gas vehicle (NGV) options continue to grow for U.S. vehicle owners, even though the number of factory NGVs from domestic OEMs has declined. According to a Natural Gas Vehicle Coalition release, ECO Fuel Systems Inc. recently announced that its latest Certificate of Conformity from the EPA allows aftermarket converters in EPA-regulated states to use the ECO system to legally adapt gasoline-powered vehicles to operate on CNG. This certificate allows the bi-fuel CNG conversion of the following vehicle models: 2005 Ford Taurus Sedan 3.0L; 2005 Ford Taurus Wagon 3.0L; 2005 Mercury Sable Sedan 3.0L; and the 2005 Mercury Sable Wagon 3.0L. More than 20,000 vehicles have been converted with products supplied or manufactured by ECO Fuel Systems Inc.