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Our research group is currently involved in the identification of aggressive drivers by means of the near field vehicle noise picked up by two onboard microphones, one for the rolling noise and another for the engine noise. We have demonstrated that aggressive drivers radiate to the near field noise levels 5-9 dB higher than the average of normal drivers [1]. In order to relate these near field measurements with the vehicle noise radiated to the far field, we must provide the corresponding extrapolation filter. This filter should contain the effects of geometrical spreading, air absorption and ground interaction. Whilst the first two are easily implemented taking into account soundly based international standards, the effect of the ground on the propagated sound from the near field to the far field depends on its intrinsic characteristics such as the type (local or extended reaction), layering and acoustical impedance of the soil.