Coastdown tests, performed on a level road on a calm day, can be used to measure aerodynamic drag and rolling resistance coefficients for a full-scale vehicle. Rolling resistance is estimated from...

Coastdown tests, performed on a level road on a calm

day, can be used to measure aerodynamic drag and rolling

resistance coefficients for a full-scale vehicle. Rolling resistance is estimated from dV/dt measured at low speed, where

aerodynamic drag is small. Rolling resistance then is

deducted from dV/dt measured at high speed to determine

the aerodynamic drag. The following data were obtained

during a test with a vehicle, of weight W 5 25,000 lbf and

frontal area A 5 79 ft2

: