Economic environment has dramatically changed because of the economic crisis. It has reminded us of the importance of vehicle development to meet needs of users, which vary according to their countries, incomes and so on. Our research group aims to introduce Total Performance Indicator (TPI) into development of automobiles. TPI can evaluate a product by one parameter from the viewpoints of not only cost and environmental burden but also customers' sense of value. However, TPI has not been successfully applied to closed integral products including automobiles. In this study, valuable knowledge is obtained that reasonable results can be calculated by applying TPI to automobiles available today. In addition, it is clarified that TPI has a potential to help the development because it can evaluate the effect of product improvement with only one parameter, taking account of customer's sense of value.
