Particulate and regulated gaseous emissions were characterized in a feasibility study for a 1994 Ford Taurus Flexible Fuel Vehicle (FFV) operating on five fuels. The five fuels included Federal Reformulated Gasoline (RFG); 85% fuel grade methanol and 15% gasoline (M85); 85% denatured ethanol and 15% gasoline (E85d); liquefied petroleum gas (LPG) meeting HD-5 specifications; and industry average compressed natural gas (CNG). The vehicle was operated fuel-rich to simulate a vehicle operating condition leading to increased production of particulate matter. This simulation was accomplished by using a universal exhaust gas oxygen sensor (UEGO) in connection with an external controller. Appropriate aftermarket conversion kits involving closed-loop control and adaptive learning capabilities allowed operation on the gaseous fuels. Particulate emissions were characterized by total mass and particle size. The regulated gaseous emissions included: either total hydrocarbons and non-methane hydrocarbons (NMHC), or organic material hydrocarbon equivalent (OMHCE) and organic material non-methane hydrocarbon equivalent (OMNMHCE); carbon monoxide (CO); and oxides of nitrogen (NOx). All tests were performed using the chassis dynamometer portion of the Federal Test Procedure (FTP) for light-duty vehicles. Even when operating the vehicle at the rich fuel/air equivalence ratio, vehicle particulate rates for all fuels were well below the 50 mg/km (80 mg/mi) particulate emission standard for 1996 light-duty vehicles.