This study assesses automobile seat comfort by using a subjective evaluation system with road trials and by measuring seat pressure. The focus of this study is to demonstrate how drivers are affected by seat comfort under actual road conditions. All experiments were carried out with 55 participants driving for at least 2.5 h. Before the participants drove, the interface pressure was measured at 9 areas in the automobile.During the road trials, a comfort assessment was performed at 4 intervals: 0 min, 15 min, 75 min and 150 min. Participants were required to complete a questionnaire of 24 questions for each section. In total, 33 parameters were evaluated using related statistical techniques with SPSS. The participants felt discomfort after 75 minutes, and seat comfort was directly affected by thermal comfort parameters. However, overweight participants found the seat to be more comfortable than subjects with a normal BMI. Evaluating during road trials is difficult, but real traffic conditions affect comfort level. In future studies, real traffic situations should not be omitted when assessing comfort. This study will help to close the information gap in this area because comfort was evaluated on the road for at least 2.5 hours with subjective evaluation system.