In this paper, a computational model for a vehicle system, consisting of a vehicle body, suspension systems and tyres, is presented along with an associated computational procedure to analyse the frequency response characteristics on a PC. The constituent physical parts of the vehicle system are idealised as equivalent substructures that exhibit the same dynamic characteristics as the physical ones. The use of equivalent substructures allows the modal synthesis technique to be employed. Applying the modal synthesis technique, a coupled formulation is obtained for the substructures of the vehicle system. Vibration modes and forced response characteristics of the vehicle system are obtained by solving the coupled formulation. To verify the accuracy of the numerical results, a bench test and a modal test of an experimental vehicle were performed. Test results are found to be in good agreement with the numerical results up to 300 Hz.