This study investigates the potential enhancement of the tensile mechanical behavior of three different plastic resins—polypropylene (PP), polybutylene succinate (PBS), and polylactic acid (PLA)-through the incorporation of argan shell powder, with a focus on applications in the automotive industry. The research employs an experimental approach to determine which of these materials can achieve improved tensile properties with the addition of this natural filler. The findings indicate low reinforcement but a slight improvement in stiffness values compared to the raw polymers, particularly with PBS showing a significant increase of +60%. The stiffness values remained unchanged for PP and showed a slight improvement of +18% for PLA. These results provide insights into the feasibility of using argan shell powder as a sustainable additive for enhancing the mechanical performance of these polymers, potentially benefiting automotive applications.