Quantifying the distribution of critical metals in conventional passenger vehicles using input-driven and output-driven approaches: a comparative study

Critical metals are used increasingly in vehicle manufacturing. For more sustainable use of these metals, it is important to understand their distribution in vehicles. In this paper, we present a comparative study examining the distribution of critical metals in conventional passenger vehicles. We identified two existing approaches to estimate the amounts of critical metals used in one passenger vehicle: input-driven and output-driven approach, and compared the results of 25 metals among five studies. In general, the results were found to be scattered. Cu, Mn, Sr and Sb were found with the highest median masses per vehicle. The median masses of eight metals (Nb, Zr, Co, La, Mo, Nd, Ce, and Ag in descending order) were around or below 10 g per vehicle and those of 13 metals (Pd, Ta, Pr, Ga, Sm, Y, W, Au, Gd, Dy, In, Pt, and Tb in descending order) were below 1 g per vehicle. Top three subsystems and parts containing the largest mass of critical metals in sum were presented. Our research provides a consolidated summary of existing information on the critical metal distribution in conventional passenger vehicles and suggests improvements for future studies on this topic.