Repairing products using recycled parts has low environmental impact and cost. However, the product value may be inferior to using a new part. Thus, determining the most appropriate repair option for a user is difficult when balancing the three factors of product value, environmental impact, and cost. Additionally, users have subjective values regarding their cars, such as driving comfort and design. In other words, the importance of various car performance is different from each user. Furthermore, some users are favorable towards recycled parts, while others may be negative. To propose appropriate repair options considering user preferences, a questionnaire was conducted to evaluate four options: “Repair by a reused part,” “Repair by a rebuilt part,” “Repair by a new part,” and “Replace the car.” The questionnaire has three main items: annual mileage, the user’s importance of car performance, and whether the user wants to use recycled parts. The objective is to suggest the most suitable repair option based on the anticipated future usage period of the car. The validity of the proposed method is examined by comparing two different user preferences, using a Kei car engine repair as a case study.

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