Material efficiency for transport decarbonization: a case study of carsharing in montreal

• Carsharing can lower carbon footprint by improving material efficiency. • Largest gains come from low-mileage users shifting to shared vehicles. • High-mileage users yield smaller or no carbon benefits with carsharing. • EV-based carsharing cuts carbon footprint up to 29% at 60% adoption rate. • Results offer a baseline for policy targeting appropriate carsharing users. This study quantifies the climate impacts and benefits of carsharing by focusing on one key mechanism: improved material efficiency through the more intensive use of shared vehicles. We assess this mechanism by evaluating how variations in annual driving distance and resulting lifetime mileage affect carbon footprints from a life cycle perspective. Adoption scenarios reflect a continuum in which users progressively shift to carsharing based on their annual driving distance, while their travel demand remains constant. Results show that most carbon footprint reductions occur between 10 % and 60 % adoption, beyond which marginal benefits decline. These reductions are driven by the collective contribution of users driving less than 15,000 km/year, with per-person impacts vary significantly depending on individual annual driving distance. While the study does not incorporate behavioral change or system dynamics, it offers a conservative, mechanism-based estimate of carsharing’s environmental potential. The findings complement behavior-oriented research on carsharing for transport decarbonization.