This paper presents experimental and theoretical investigations for ride comfort performance of compressed natural gas fuelled car. A compressed natural gas and gasoline fuel are used to run the engine car and its effect on the vehicle ride comfort is evaluated. The ride comfort performance in terms of experimental Root Mean Square (RMS) values of the vertical acceleration at near driver's feet on the floor, on the front and back seat for the same passenger car fuelled by gasoline and natural gas is evaluated. Furthermore, seven degrees of freedom vehicle mathematical model is developed, and validated through laboratory tests. The validation process is performed by comparing the predicted RMS values of the vertical accelerations with the measured RMS values. Furthermore, the optimum values of vehicle suspension parameters are obtained through the validated vehicle model. The experimental results showed that the car fuelled by compressed natural gas gives a significant improvement in the ride comfort compared with the same car fuelled by gasoline. The best ride comfort is found on the back seat. The experimental results of the vehicle using the compressed natural gas and the theoretical results obtained indicate that the mathematical model produces optimistic results for the vertical direction of body accelerations. The predicted results show optimum values of vehicle suspension system elements.