A recent trend in vehicle seating design is the change in structure from a spring / foam composite to a foam and dead pan structure. For a composite design, the seat vibrational characteristics are tuned for the vehicle by adjusting the spring stiffness. In a dead pan design, however, foam dynamics solely dictate seat vibrational characteristics.Foam vibrational transmissivities measured by a laboratory test are compared with transmissivities measured with human subjects and road profiles. The in-vehicle vibrational performance of the foam has been quantified using the S.E.A.T. method for several vehicle categories. The role of foam dynamics has been quantified for full foam seats.