The Fuel Consumption of Automobiles

Abstract

The necessity for fuel consumption is clear. Automobiles, as users of nearly 60% of transportation energy (1/4 of total energy consumption), is a prime target for consumption measures. The author here suggests ways by which auto efficiency can be increased at least 40% by 1980. Use of mass transit would reduce the fuel used on short trips (those less than 10 miles), which account for nearly 1/3 of vehicle miles traveled. Use of freeways and computerized signal control reduces traffic delay, a cause of poor mileage. Apart from enforcement of the 55-mph limit and the essentially voluntary measures listed above, more efficient autos are the best source for fuel savings. The author cites statistics regarding fuel consumption of the various weight classes of cars. Weight is a factor both at low and high speeds: in the former tire pressure and suspension systems contribute to rolling resistance, which absorbs approximately 24.7% of engine power; at higher speeds, approximately 25% of engine output is absorbed by aerodynamic drag. Exterior design of autos can reduce the impact of these factors. The author also considers more efficient accessories and warm-up. In the area of engine efficiency, the author discusses diesel, stratified-charge and hydrogen admixture engines, with attention given to emission standards. The use of catalytic converters and subsequent lowered compression ratios due to the use of unleaded fuels is considered, as is the possibility of electric cars. The DOT-EPA report "Potential for Motor Vehicle Fuel Economy Improvement" is cited, and graphs and charts accompany the article.