Realistic Effects of Winds on the Aerodynamic Resistance of Automobiles

To date the effects of winds on the computed fuel economy of highway vehicles have been omitted or included in simple ways. This paper presents the results of a rigorous computer study on the realistic effects of winds upon the aerodynamic resistance, and consequently, upon the fuel consumption of automobiles for EPA driving cycles. The aerodynamic resistance was a function of the instantaneous wind direction and speed relative to the car. A wind spectrum having an annual speed of 10 mph will increase the zero-yaw aerodynamic resistance by 16% for the Combined driving cycle. Several simplistic approaches were evaluated against rigorously obtained results.