Ambient Temperature and Trip Length-Influence on Automotive Fuel Economy and Emissions

Experimental work was done to examine the interrelationships among automotive fuel economy, ambient temperature, cold-start trip length, and drive-train component temperatures of four 1977 vehicles. Fuel economy, exhaust emissions, and drive-train temperatures were measured at temperatures of 20, 45, 70, and 100° F using the 1975 Federal test procedure and the Environmental Protection Agency's highway fuel economy test. Results showed that vehicles used for short cold-start trips consume fuel at a much greater average rate than during long trips, and the effect is magnified with decreasing ambient temperature.