A request for a waiver to permit use of ten percent Ethanol in gasoline ('gasohol') was considered by EPA-Mobile Source Enforcement Division (MSED). The Emission Control Technology Division (ECTD) in Ann Arbor, Michigan was requested to assist MSED by testing ten vehicles on two gasoline fuels and three gasohol fuels. In addition, ECTD directed Southwest Research Institute (a contractor laboratory) to test three vehicles on the five fuels plus other fuels containing methyl tertiary butyl ether (MTBE) and teritary butyl alcohol (TBA), other fuel additives for which waivers have been requested. EPA-ORD was requested to provide more extensive emission data on two test vehicles. Since the completion of the ECTD test program described in this report, EPA has acted to allow the use of ten percent ethanol in gasoline. Future control of this or other fuel additives is authorized under Section 211 of the 1977 Amendments to the Clean Air Act.