Automobile Fuel Use and Conservation

Eric Hirst

DOI: 10.2190/CX0W-YBKY-NWN0-1943


Variations in automobile fuel economy as functions of trip length and of driving conditions (urban and inter-city) are calculated for subcompact, "average," and full-size cars. Fuel economy is considerably worse for urban driving than for inter-city driving because of cold-start operations and frequent stop-and-go cycles for urban driving. Fuel economy improves markedly with increasing trip length because the adverse impact of cold start is spread over more miles. Subcompacts achieve much better fuel economy than do full-size vehicles under all conditions; this is especially so for urban driving.

A number of strategies exist that could be used to conserve fuel by discouraging short auto trips and by discouraging the use of large cars. These strategies include: shifts from automobiles to public transit, shifts from automobiles to bicycles for short trips, shifts from full-size to subcompact automobiles, increases in automobile occupancy, and reductions in the overall level of automobile travel.

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