Results of a 1982 study published by the Federal Highway Administration (FHWA) show that trucks can save as much as 2 miles per gallon by driving on concrete instead of asphalt pavements, even when the pavement surfaces are similar in roughness. The study was prepared for FHWA by John P. Zaniewski, assistant professor of engineering at Arizona State University, to analyze the relationship between highway design and vehicle operating costs. The study focused on concrete and asphalt pavements with intermediate to smooth riding qualities typical of most major highways in the United States. Vehicles were driven on the test pavements at constant speeds of 10, 20, 30, 40, 50, 60, and 70 mph while fuel consumption, speed, and other factors were monitored.
Fuel consumption for cars was not affected by the type of pavement surface. But trucks used more fuel on asphalt than on portland cement concrete in every test at speeds of 20 mph or greater. Because trucks are heavier than cars, they cause more deflection on flexible pavements, such as asphalt, than on rigid pavements. A truck always runs in a slight depression on asphalt so more energy, and consequently more fuel, is needed to propel it.