In light of the probable shortage of liquid petroleum fuels in the United States for the foreseeable future, much attention is being focused on possible fuels as substitutes for conventional gasolines and distillate-type fuels. This paper surveys the presently available synthetic or substitute fuels being considered for transportation uses. The survey includes a brief review of current energy use patterns in the transportation sector and a projected future for the automobile and other transportation modes. Specialized fuels needs for the transportation sector are described including attributes of the ideal fuel.Discussion of possible synthetic fuel candidates is broken down into categories-hydrocarbons, hydrogen, inorganic hydrogen compounds, and electrochemical systems-and general properties. The properties of an idealized synthetic fuel are formulated and correlated with the properties of the ideal transportation fuel, and an extensive comparison of the selected synthetic fuel candidates is made. A significant portion of this comparative information is presented in graphical and tabular form with appropriate discussion of the data and its presentation.The paper concludes with a discussion of the application potentials of the various synthetic fuel candidates to various modes. Interim and long-term fuel possibilities are proposed for further consideration.