SYNOPSISThere are growing demands for higher-performance yet less-gasoline-consuming cars, thus combining the essential automobile function with fuel conservation in these days of slow economical growth. In view of this background, development was made on a concept car incorporating maximum use of technologies which meet such demands and have high feasibility for production. A 1490cc four-cylinder engine had a number of fuel-saving techniques incorporated, such as those for reducing mechanical resistance of the piston and rings and increasing compression ratio, swirl intensity control system (Dual Induction System), and variable displacement system. Also, in order to bring out a maximum performance of the engine, an electronic system for controlling fuel flow, ignition timing, EGR ratio, and idle speed was adopted. The concept car has been reduced in its inertia weight class from 1000 kg, original production-level, to 875 kg by using light-weight materials. The rolling resistance also has been reduced. Through matching and evaluation including the choice of the gear ratio, the concept ear has achieved 30 percent fuel economy improvement over a 1982 model, while keeping a power output of a present production car level. In addition, application of a simulation program has helped identify the contribution of each design factor to the fuel economy improvement.