IMPROVEMENTS IN AUTOMOTIVE FUEL ECONOMY

Factors influencing automotive fuel economy are discussed: body shape (effect on air and rolling resistance), vehicle weight, fuel type, and drivetrain effectiveness. Other factors include driving mode and traffic environment. The interactive effect of drag coefficient, inertia weight, and engine power on fuel economy is discussed. Potential improvements in the gasoline engine include more precise mixture control, optimization of ignition point and valve timing, leaner warm-up phase, higher compression, lower friction losses, utilization of waste heat (by turbocharging), and engine displacement adapted to driving needs. Electronic systems for mixture control, ignition-map control, and knock sensing for a gasoline engine are diagrammed. The Volkswagen Integrated Research Vehicle is described. The drivetrain includes a 70 hp swirl chamber diesel engine with turbocharger and a manual five-speed transmission. Fuel economy of 60 mph was achieved with excellent acceleration. A possible future improvement to the diesel engine is direct fuel injection. Five-speed transmissions are designed for fuel economy; a possible improvement is free-wheel drive. Electronically controlled transmissions with pneumatic or power-assist components are a long-term possibility. Reference is made to regulations imposed by contradictory government policies which impede development of automobiles with maximum fuel economy (up to 80 mpg). Included are regulations controlling particulates, nitrogen oxides, and noise emission, safety regulations, and sales weighted average projection requirements. Electricity and alcohol (methanol and ethanol) are mentioned as possible mid-term alternative sources of energy.