This study was aimed at clarifying the design process of car package elements. First, essential elements of car package design were identified, and these were used in an analysis by interpretive structural modeling (ISM) graph theory. Typical samples were extracted and structured graphs were made for three product categories (4-door sedans, 2-door coupes, and town use RVs). As a result, from these graphs it was possible to determine the essential characteristics underlying concepts of the categories; personal comfort for 4-door sedans, sports touring for 2-door sedans, and in-car entertainment for town use RVs. It is thus possible to design new vehicle packages by application of these representative structured graphs.