This paper proposes a new method for diagnosing passenger car bodywork during service. The method is based on the process of 3D scanning specific areas of the bodywork. The study involved tests using this method on cars exposed during use to various factors contributing to bodywork wear. This allowed the method’s suitability to be verified. The tests were carried out on a car that had undergone bodywork repairs following a road collision, on a car that had been used intensively, and on a car with low mileage. Following the 3D scan of the bodywork, measurements of the floor panel geometry and the upper sections of the bodywork were carried out using traditional methods and diagnostic tools. This allowed the results of the 3D scan to be compared with those obtained in previous studies. A comparative analysis of 3D scanning of three passenger cars, which were exposed to various factors contributing to bodywork wear during their service life, shows that the method proposed in this study can be used to assess the condition of the bodywork whilst the vehicle is in use. By applying the described method, the most likely cause of bodywork wear can be identified. Comparing the results of the analysis of changes in bodywork geometry using 3D scanning with measurements of the floor panel and upper bodywork sections using traditional diagnostic methods, it can be concluded that similar relationships were obtained. The greatest extent of bodywork deformation was observed in the car that had undergone bodywork repairs to the left side of the body, which had been damaged in a road collision. Minor changes in body geometry were found in the car that had been used intensively by many drivers. In contrast, the smallest changes in body geometry were found in the car with the lowest mileage, which had been used by only one driver.