The future generation of lightweight materials? A life cycle assessment of fiber-reinforced composite cross car beams

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 with explicit composite EoL modelling 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.