Product shapes have tight relations with user’s preference. However, it is difficult for product designers to quantify the characteristics of product shapes and predict the preferred shapes. The author proposed a numerical method to quantify characteristics of smartphone shapes. Since the result showed a negative correlation between product impression strength versus user’s preference, it was suggested that vigorous and weak impression is preferred. However, since smartphone has small shape variations, it is not a good example in validating the effectiveness of the method. In this research, a new case study for automobile shapes was carried out. As the result, it was suggested that the users can be categorized to some groups having different shape preferences. Since both groups preferred the shape with weak impression, it was suggested that people generally prefer simple and clear shapes for products. However, since the difference of the induction field value was small, this tendency should be examined through further study.