Exporting sustainability? Assessing the environmental trade-offs of secondhand electrified and conventional vehicle flows from Japan to the global south and beyond

As developed economies accelerate fleet renewal toward cleaner vehicle technologies, used-vehicle exports to the Global South are surging, yet their environmental consequences have not been systematically assessed. This study quantifies the net life-cycle climate impacts of Japan’s used-vehicle exports for four powertrain types across ten destinations and identifies their system-level drivers. A modular attributional life cycle assessment with avoided-burden modeling was developed for screening. It decomposed the post-deregistration life cycle into manufacturing life extension, transport, second-life operation, and end-of-life material recovery, and evaluated it against a domestic recycling case. Three reference cases bounded the contribution of end-of-life recovery to the net climate balance. Without destination recovery, exports were net climate burdens for all powertrains except EVs on very low-carbon grids, and mean net GWP was approximately 8,400 kg CO 2 -eq per vehicle higher than under domestic recycling. With destination recovery, HEVs, PHEVs, and EVs were net-beneficial across all ten destinations (− 8,500 to − 140 kg CO 2 -eq per vehicle), largest for EVs and smallest for HEVs, whereas ICEV outcomes were destination-dependent. Only the EV benefit was robust to the basis used to credit recovered aluminum; HEV outcomes reversed to net burdens when recovered aluminum was credited against secondary cast alloy. Material recovery ranked first among system-level drivers, followed by grid carbon intensity and powertrain type; transport distance did not alter the ranking. The climate benefit of used-vehicle trade is therefore not inherent to life extension: it requires destination material recovery for ICEVs, HEVs, and PHEVs, and for EVs it arises without recovery only on very low-carbon grids.