The aim of this study is to design and check the performance of fuzzy logic-controlled (FLC) semi-active suspensions on a non-linear full vehicle-model with seven degrees of freedom, without causing any degeneration in suspension working limits. Aiming at zero displacement for the sprung mass might finish the suspension working distance because the controller uses the needed space to change the suspension length. For this reason, a new approach is suggested in this study. Linear combinations of the vertical velocities of the suspension ends and the accelerations of the suspension connection points to the body have been used as input variables. The results obtained with the vehicle system controlled by fuzzy logic are compared with those from the conventional proportional-integral-derivative (PID) controlled system and passive suspension system.