Ride comfort of the passengers in a vehicle largely depends on the vibration isolation performance of its suspension system. This paper aims at vibration isolation analysis of both heavy-duty and light-duty vehicle suspension systems to corroborate ride comfort perception. A half car model with passive suspension and having five degrees of freedom has been used to investigate the dynamic response i.e. the vibration with eccentricity under sinusoidal input excitations of a rough road. The mass of the vehicle body, front/rear wheels and driver/passenger; mass moment of inertia of the vehicle body; damping coefficients and spring stiffness of front/rear suspensions; distances of the driver/passenger's seat (eccentricity) and front/rear suspension locations from the centre of gravity (CG) of the vehicle body; pitch angle – all these are considered as variable parameters. A model is created in SIMULINK of MATLAB for simulation of the vehicle's random response and ride comfort characteristics.