The Effect of Ambient Wind on a Road Vehicle's Aerodynamic Work Requirement and Fuel Consumption

A Wind Factor, W, has been developed to account for the effect of ambient wind on the aerodynamic work required by any road vehicle during any single driving experience. It has been evaluated for a broad range of wind and aerodynamic characteristics for three relevant types of driving. Values substantially larger than unity can be experienced, reaching levels like 5.5 (a 450 percent increase in aerodynamic work over the zero-wind case) on the EPA Urban schedule. Adverse wind effect (W-1) occurs for substantially more than half the possible wind angles relative to the road.

A functional form for the effect of wind on fuel consumption has been developed. Wind effect is represented by (W-1), and it translates to a fractional change in fuel consumption through an influence coefficient which depends on the particular chassis-drivetrain-driving mode combination being considered. This impact on fuel consumption provides additional incentive for reducing the aerodynamic drag of road vehicles.