Strategic Materials at Reaction Temperatures (SMART) is an approach used to design washcoat systems for passive 4-way emission control catalysts. Light duty diesel vehicles need to meet the European Motor Vehicle Emissions Group (MVEG) cycle or U. S. Federal test procedure (FTP 75). Emissions that are monitored include hydrocarbon (HC), nitrogen oxides (NOx), carbon monoxide (CO) and total particulate matter (TPM). Low engine-exhaust temperatures (< 200°C during city driving) and high temperatures (> 500-800°C under full load and wide-open throttle) make emission control a formidable task for the catalyst designer Gas phase HC, CO and NOx reactions must be balanced with the removal of the soluble organic fraction for the vehicle to be in compliance with regulations.The SMART approach uses model gases under typical operating conditions in the laboratory to better understand the function of individual washcoat components. Based upon the results, robust washcoat constituents arc identified and then optimized for specific applications. Components are matched to obtain synergism, that widens the performance window. Engine aging and vehicle evaluations demonstrate efficacy. For the end user, SMART developed catalysts result in a cost-effective solution.