Vehicle lightweighting for carbon neutrality: decarbonization mechanisms, key processes and engineering applications

Abstract The transport sector is under increasing pressure to contribute to national and global carbon-neutrality targets, and vehicle lightweighting has emerged as a core technical route for reducing energy use and CO₂ emissions. This review examines vehicle lightweighting from a decarbonization and life-cycle perspective, moving beyond traditional mass-reduction thinking toward integrated “lightweight decarbonization process systems”. First, the physical mechanisms by which mass reduction lowers tractive energy demand are analyzed for conventional and electrified powertrains, together with the secondary effects of powertrain downsizing and reduced parasitic losses. The role of life-cycle assessment (LCA) in quantifying trade-offs between higher embodied emissions of lightweight materials and use-phase energy savings is then discussed, including the influence of vehicle duty cycles, energy mixes and recycling rates. The review summarizes major technology routes for lightweighting body-in-white, chassis, powertrain and new energy vehicle subsystems, and highlights high-value opportunities in exhaust aftertreatment and thermal management systems. Key enabling processes—including low-carbon material preparation, advanced forming and casting, multi-material joining, surface engineering and digital design—are analyzed as the foundation of lightweighting-oriented decarbonization. Representative engineering applications and industrial case patterns are used to illustrate typical magnitudes of mass and CO₂ reduction and to extract lessons for integrating lightweight design with recycled and low-carbon materials. Finally, the paper identifies critical scientific questions, process and manufacturing bottlenecks, and cross-scale digitalization needs, and outlines promising directions for future “key technologies and applications” in vehicle lightweight decarbonization, with a particular focus on life-cycle CO₂ performance and real-world demonstrator platforms.