A new TWC substrate with 30% less mass heats up faster for reduced hydrocarbon emission during the FTP-75 cold start idling period (0–20 s). Republished with permission of SAE International, from Development of a Super-Light Substrate for LEV III/Tier3 Emission Regulation, S. Otsuka, Y. Suehiro, T. Tanner, D. Bronfenbrenner, T. Tao and K. Twiggs, SAE Technical Paper, 2015, 2015-01-1001, Copyright © 2015.