Summary Appropriate modelling of the dynamic behaviour of the vehicle components, particularly car body flexibility, is essential in the analysis of railway vehicle comfort performance, especially for high-speed vehicles. This paper deals with the description of the adopted approach to set up a complex numerical model of the railway vehicle, suitable for reproducing its dynamic behaviour in the 0–50 Hz frequency range, especially with respect to the ride comfort problem. The implemented model is used to simulate in time domain the dynamic behaviour of a vehicle running on irregular track. Numerical results are validated by means of comparison with experimental data of on-line tests. Finally, the analytical model is used to perform a sensitivity analysis, in order to point out the parameters that most significantly affect comfort.