The purpose of this study is to analyze customers’ satisfaction for the stiffness of outside panels of passenger cars. Including ‘satisfaction’, four affective variables were selected for rating affection of outside panel stiffness. About fifty customers evaluated the hood and trunk lid of nine midsize passenger cars with a developed questionnaire in the study. The stiffness of the hood and trunk lid for the nine vehicles was measured using stressstrain curves. It was found that customers were more satisfied as the slope of the stress-strain curves increased, and the decrease at a point in the curve had negative effects. In this study, the levels of satisfaction of outside panel stiffness were grouped by stress-strain curves, and it is likely that the affective quality of outside panel stiffness can be controlled by them. With the results of this study, the designers of outside panels are able to know how to make the stress-strain curves of panels for the desired level of satisfaction.