Near term technical alternatives available to automobile manufacturers for increasing passenger automobile fuel economy are described. Report examines automobile modifications providing improved fuel economy for six vehicle classes: Subcompact, compact, loaded compact, intermediate, standard, and luxury. For each combination of alternative and class considered, the results include incremental gasoline savings, capital and operating costs both to the manufacturers and consumer, and the number of years required to put the alternative into production. The composite nature of each class of passenger automobile that would be produced under a variety of tax and regulatory schemes during production years 1974-85 is predicted.