Abstract—Ride quality and road holding capacity of a vehicle is significantly influenced by its suspension system. In the design process, a number of criteria related to comfort and road holding capacity is taken into consideration in order for achieving the optimum vibration performance. Therefore, multiple design objectives have to be optimized. In this paper, a five-degree-of-freedom system of vehicle vibration model with passive suspension is investigated. This paper formulates the model into multi-objective optimization problem consists two design objectives. The improved compressed objective genetic algorithm (COGA-II), a Pareto-based multi-objective optimizer, is used as the search algorithm. The vehicle model is excited by the bump that the model passes on. Since there might be some differences on optimized solutions on regular and random road profiles, the study on the differences should be consequently investigated. There are 4 cases – 0%, 10%, 20%, and 30% randomization on the bump profile to be studied. Simulation results reveal that there is some significant difference on optimized solutions.