In this study, considering four different car models, random vibration characteristics of a road vehicle are investigated by using Mathematica. A road vehicle is modeled as quarter car, half car, and bicycle car. Natural frequencies of each model are found in first step. Then, responses to harmonic and random base excitation for each models are determined. The accuracy of the developed programs for different car models in Mathematica is evaluated by comparing the natural frequencies available in the literature. The effects of modeling approach on natural frequencies and response to harmonic and random base excitation are obtained. The results are presented in graphical and functional forms.