Shared autonomous vehicles (SAVs) present a new challenge for design engineers and policymakers aiming to enhance urban mobility and achieve sustainability. Despite the growing interest in SAVs, the role of vehicle design in their adoption remains understudied. This study adopts a transdisciplinary approach, viewing vehicle design as a complex system influenced by various factors such as societal needs and market acceptance. By applying structural equation modelling within the Unified Theory of Acceptance and Use of Technology (UTAUT) framework, we assess how interior and exterior design elements influence user adoption. A total of 313 valid survey responses were collected for analysis. The results show that both interior and exterior design elements positively influence users’ hedonic motivation, effort expectancy, performance expectancy, and price value. However, safety risks act as barriers to SAV usage, with no clear correlation with perceived design quality. This study also conducted a comparative analysis across gender, driving experience, transportation mode, and anticipated scenarios. Overall, this study provides valuable empirical insights into the role vehicle design plays in shaping user acceptance of SAV services, providing a fresh viewpoint advocating the integration of strategic design elements to expand the potential of urban transportation systems.