Indonesia has been one of Southeast Asia’s largest used car markets. Approximately 2.5-3 million used cars are sold annually. The increased competition in the automotive industry has heightened the emphasis on improving customer relationships. ABC Showroom (pseudonym) is a local used car dealer in Bukittinggi currently facing unsatisfactory sales performance and lacking relationship marketing strategy. The aim of this research is to formulate the relationship marketing strategy for ABC Showroom and find out whether the strategy differs amongst its customer persona. Internal analysis and external analysis are conducted to formulate the strategy. The internal analysis consists of marketing mix (7P) and STP analysis. The external analysis includes PEST analysis and competitor analysis. A quantitative approach using a survey is carried out to collect information on target market preferences regarding the proposed relationship marketing strategy, specifically personal selling, personalization, and after-sale service. The total of respondents obtained in this research is 240 respondents. The Two-step clustering analysis is conducted to build the customer persona of ABC Showroom. Analysis continued by conducting the Kruskal-Wallis test to find out if the proposed strategies differ amongst customer persona. Based on the result of the Kruskal-Wallis test, the proposed strategies do not differ amongst customer persona. Findings on internal analysis and external analysis are summarized with a SWOT matrix. Then the TOWS matrix is used to assist the author in formulating the relationship marketing strategy while tailoring it with the survey result. The relationship marketing strategies proposed includes improving salesperson performance by providing target and uniform, providing remarkable test drive experience, providing proactive and caring customer service, providing personalized offers and car products, and providing after-sales services such as warranty, repair, and maintenance service, car ownership transfer and vehicle plate transfer assistance, and car tax payment assistance.