Because of the growth in world population and the need to improve living standards, world energy requirements will increase rapidly. A world energy shortage is expected to develop at least by 1990, and probably earlier. In supplying future energy needs, the world must shift from a predominantly petroleum-based economy to one which will phase in other energy sources. Actions have been taken in the United States to reduce the amount of energy used in transportation, one of the major energy consuming segments. There are an estimated 75 million small engines in use in the United States. The growth rate of small engines is expected to accelerate but they will continue to account for only a minor portion of total energy requirements.