Japan's truck production in 1962 accounted for 70% of total vehicles manufactured. Of this, 85% consisted of compacts and midget models for use by private enterprises and over congested narrow roads. Because of severe operating conditions on unpaved bumpy roads, large payloads require sturdier vehicles and higher ratios of power to weight than do those in other countries. Passenger bus transportation is expanding and extending service distances. Practically all large vehicles are diesel powered, but smaller ones are gasoline powered. The modernization of highways will bring larger and speedier models with more engine horsepower for longer distances.