In this study, Life Cycle Assessment (LCA) was employed to compare the environmental impacts of bio-based polymers with those of conventional plastics in the automotive sector. Energy consumption, greenhouse gas emissions, land use, water consumption, and end-of-life treatment were analyzed throughout the material life cycle. Findings indicate that traditional plastics, while cost-effective and durable, contribute significantly to emissions and environmental degradation. In contrast, bio-based polymers such as PLA, bio-PE, and bio-PA demonstrate lower carbon footprints and better alignment with circular economy principles. However, their widespread adoption is limited by higher production costs, variable mechanical properties, and challenges in large-scale implementation. The study also discusses regulatory frameworks—ISO 14040/44, ASTM D6866, EN 16760, and the EU End-of-Life Vehicle Directive—that guide sustainability and compliance. Overall, bio-based polymers represent a promising path toward greener automotive materials, provided that technical, economic, and policy barriers are overcome through innovation and supportive legislation.