Decarbonizing China’s private passenger vehicles: A dynamic material flow assessment of metal demands and embodied emissions

The continuous growth of China’s private passenger vehicle fleet has intensified material demand and embodied carbon emissions, underscoring the need for effective decarbonization pathways. This study develops a transferable, dynamic material flow analysis framework to assess vehicle stocks, metal flows (steel, aluminum, and copper), and embodied emissions from 2000 to 2070, and to quantify the contributions of demand-side and technology-side efficiency measures. The results reveal that: (1) The vehicle fleet is projected to peak at 327–507 million vehicles by mid-century, with new energy vehicles dominating both in-use stocks and end-of-life flows by the 2040s. (2) Cumulative metal demand is projected to reach 1914–2990 million tonnes over the upcoming five decades, with 879–1320 million tonnes supplied from secondary sources under baseline conditions. Technology-oriented measures substantially enhance recycling performance, enabling secondary steel to fully meet manufacturing demand and allowing aluminum and copper cycles to approach near closure by 2070. (3) Correspondingly, cumulative embodied carbon emissions from vehicle metals by 2070 range from 4958 to 9218 megatonnes of carbon dioxide, with technological upgrading reducing emissions by 1051–1619 megatonnes. In collaborative scenarios, demand management accounts for 64.3% of total emission reductions, while technology-oriented measures become increasingly important over the medium to long term. Overall, the findings demonstrate that unmanaged demand growth can substantially offset technological mitigation gains, highlighting the necessity of integrated demand- and technology-oriented strategies. This study provides a systemic and transferable framework to guide circular economy development and deep decarbonization transitions in vehicle fleets in China and other emerging economies. Graphical abstract. A metal use efficiency modeling framework for China’s private passenger vehicle fleet. The graphic illustrates: (a) the role of metals in the manufacturing and processing stages of passenger vehicles; (b) scenarios and measures designed to enhance metal use efficiency; (c1) total stock of China’s private passenger vehicle fleet; (c2) metal demand and recycled metal flows; and (c3) embodied carbon emissions under different scenarios in 2000–2070 • Developed a transferable dynamic MFA framework linking vehicle stocks, metal flows, and emissions. • Passenger vehicle fleets peak at 327–507 million by mid-century, with NEVs dominating by the 2040s. • Cumulative metal demand reaches 1914–2990 Mt. by 2070, with up to 1320 Mt. supplied from recycling. • Embodied emissions reach 4958–9218 Mt. CO 2 by 2070, depending on demand and technology levels. • Technology upgrades cut 1051–1619 Mt. CO 2 , while demand management delivers 64.3% of reductions.