Introduction This report provides information on certain flues that are being used or have been suggested as alternatives to motor gasoline (SAE J312. Automotive Gasoline's) or automotive diesel fuel (SAE J313. Diesel Fuels) for use in spark-ignition or compression-ignition engines. Some of these fuels are derived from petroleum while others are from non-petroleum sources. Other than gasoline@ the flues commonly used in spark-ignition engines are propane@ frequently referred to as LPG (liquefied petroleum gas); gasohol (Ref.1) a blend of 90 recent by volume unleaded gasoline and 10 percent by volume denatured@ nominally anhydrous ethyl alcohol (ethanol); laded gasohol-a blend of 90 percent by volume leaded gasoline and 10 percent by volume ethanol; and gasoline's containing methyl tertiary butyl ether (MTBE)@ tertiary butyl alcohol (TBA)@ and mixtures of methanol and tertiary butyl alcohol. Possible alternative flues include compressed or liquefied methane@ and other alcohols and ethers@ either neat or blended into gasoline. The ethers and alcohols are sued as octane improving agents and fuel extenders. Ethanol of 92.5-93.8 percent by weight alcohol content is used as the fuel in many of the cars currently manufactured in Brazil. Methyl alcohol (menthanol) is used in some European gasolines is currently being evaluated in many countries@ and is also widely used as a racing fuel. Except when used at low concentrations of less than 15 percent by volume as blending agents in gasoline@ these alternative fuels require engine and/or vehicle modifications@ and may also require changes in lubricating oil characteristics to provide optimum engine durability. Distribution and storage facilities may also have to be modified. Only diesel fuel is used in compression-ignition engines at present One practical alternative is a wide-boiling range petroleum fuel. Use of such fuel would likely require some engine and/or vehicle changes@ but would probably not require any changes in distribution or storage facilities. Fuels derived from biomass source are being widely investigated as a means of extending diesel fuels.