Fiber-reinforced composites offer promising lightweight alternatives for automotive applications, yet comprehensive life cycle assessments (LCAs) comparing them with conventional metal components remain limited. This study presents the first cradle-to-grave LCA evaluating a recyclable multi-material glass-fiber-reinforced polymer (GFRP) composite cross car beam (CCB) against an aluminium reference, considering 11 CML midpoint impact categories under different scenarios. The study has been conducted as part of a larger research project aimed at supporting the development of a more sustainable GFRP composite CCB. The composite redesign achieves lower cradle-to-grave impacts across 10 of 11 categories, with reductions of 35–37% in toxicity-related impact categories and 8–16% in Global Warming Potential. Ozone Depletion Potential represents the only trade-off (~12–13% increase), attributable to proxy-based inventory data. Despite replacing ~40% of the aluminium mass, residual aluminium supply for the hybrid composite structure dominates upstream impacts, while end-of-life (EoL) recycling credits prove decisive for resource depletion categories. These results indicate that environmental performance in hybrid multi-material composite architectures is governed by metal substitution, scrap minimization, and EoL recycling quality - conditions increasingly decisive as powertrains electrify and electricity grids decarbonize.