The present work describes the modeling and analysis processes of a medium sized truck manufactured in Brazil with regard to comfort behavior. The vehicle model includes Hotchkiss suspensions front and rear with shackle and with a double stage with bump stops at the rear. It is also included frame flexibility in ADAMS in an approximate manner based on a Finite Element Analysis of the frame. Nonlinear shock absorber curves are also represented for the vehicle and cab suspensions. Viscoelastic bushings for cab and powertrain suspension are also included. Random track profile is generated as input and vehicle comfort is described in terms of the ISO 2631-85 Standard. The effect on vehicle comfort of changing a design parameter can be predicted in the model and verified experimentally.