Old is gold? Vehicle maintenance material demand of lifetime extension: dynamic stock modelling

Transport vehicles are a major driver of global material extraction, making their material needs central to circular economy strategies. Yet few studies address the material implications of maintenance, leaving the link between vehicle lifetime extension and maintenance poorly quantified. Using a new global, stock-driven model, IMAGE Materials, coupled to the IMAGE integrated assessment model, we link material demand to transport services and account for scheduled maintenance for land-based transport. Results show that maintenance adds ∼30 % of material demand for road vehicles and up to 100 % for high-speed rail. Maintenance flows for road modes are rubber-intensive, while rail requires steel. Still, lifetime extension leads to a net reduction in total material demand of ∼16 % (95.8 Mt) in 2100, but increased maintenance partly offsets these savings, adding 69.5 Mt with age-related or 29.3 Mt with age-capped maintenance material growth. These findings highlight maintenance as a structural component of vehicle material demand, requiring complementary policies like standards and repair incentives. The graphical abstract summarizes the core research finding that vehicle maintenance requires approximately 30% additional material compared to vehicle production. On the left, total material inflow is shown for all included transport modes, separated into maintenance (below the black dashed line) and production (above the black dashed line). On the right, the included modes are illustrated with relative sizes indicating the total maintenance material required over a vehicle lifetime, further divided into rubber and non-rubber shares.