The oleo pneumatic (hydropneumatic) car suspension with self-leveling system is an essential part for any controlled suspension in modern vehicles. Therefore, the performance of the hydropneumatic vehicle suspension has been studied in the present work. A mathematical model for a hydropneumatic suspension composed of hydraulic accumulator, double acting shock absorber and power cylinder has been deduced. The mathematical model has been solved numerically, using the MATLAP simulink program, to predict the dynamic performance of the hydropneumatic suspension. Experimental tests using the MTS damper test system have been applied to validate the results. The experimental testing and theoretical results have been compared; good agreement between them has been found. The developed mathematical model for the hydropneumatic suspension has been applied to a two-degree of freedom vehicle model representing the vehicle body and wheel assembly. The dynamic response of the vehicle body has been obtained. The effect of different construction parameters and working conditions on the dynamic response has been studied in order to obtain the optimum values of these parameters.