Understanding and measuring a vehicle's response to cyclical vertical inputs is fundamental to evaluating suspension tuning and handling characteristics. By using a frequency sweep with in-phase and out-of-phase decreasing displacements to the tires, the vehicle sprung and unsprung mass responses can be measured to quantify vertical accelerations across a frequency range. With these data, the resonant frequency characteristics of the front and rear suspensions can be determined. In addition, the acceleration gains of the unsprung mass and the vehicle body can be calculated. This evaluation is effective in identifying the similarities and differences in suspension response among various vehicles and in quantifying the changes of the response to various types of suspension tuning.