Growing world vehicle populations and persistent air quality problems require further reductions in the emissions from engines. Future tailpipe emission limits mandate 98%+ reductions in hydrocarbons, 95%+ reductions in Carbon Monoxide and 95%+ reductions in Nitrogen Oxides. Further complexities are introduced by new, demanding driving norms according to which these standards are applied, as well as the on-board diagnostics to ensure in-use compliance. Customized and optimized emission control system designs will be needed for each specific engine family. The new emission control systems will incorporate integrated heat management, advanced catalyst formulations, optimized substrates and substrate packaging as well as the use of pollutant storage materials and supplemental heating devices. New engines, computerized controls, compact substrates and new catalyst and adsorbent materials will provide the emission control engineer with cost effective options to meet the expected reliability and performance.