The use of fractional differentiation in vehicle suspension design has many interests. This paper presents a hydropneumatic suspensions design method based on fractional differentiation. Once an hydraulic structure has been chosen for the suspension, it is possible to calculate the values of all technological parameters, so that the suspension force - deflection transfer function is a band-limited fractional differentiator. The combination of the CRONE control methodology and of hydropneumatic technology leads to remarkable performances of robustness.