To evaluate the performance of a variety of commercially available exhaust emission control technologies, the Manufacturers of Emission Controls Association (MECA) sponsored a test program at Southwest Research Institute (SwRI). The test engine was a current design heavy-duty diesel engine operated on standard No. 2 diesel (368 ppm) and lower sulfur (54 ppm) diesel fuel. Technologies evaluated included: diesel oxidation catalysts (DOCs), diesel particulate filters (DPFs), selective catalytic reduction (SCR), fuel-borne catalysts (FBCs) in combination with filters and oxidation catalysts, and combinations of the above technologies. The program was structured to demonstrate that a variety of exhaust emission control technologies, including exhaust gas recirculation, could be used to substantially reduce emissions from a modern MY 1998 heavy-duty diesel engine. Objectives set for the program were:to demonstrate that PM emissions of 0.03 g/bhp-hr combined with NOx + NMHC emissions of 1.5 g/bhp-hr could be achieved using commercially available diesel fuel, and that PM emissions of 0.01 g/bhp-hr combined with NOx + NMHC of 1.5 g/bhp-hr could be achieved on lower sulfur fuel (54 ppm in this instance).Results of the test program clearly indicated that the above emission levels were met. Further testing demonstrated that even lower emissions could be achieved with zero sulfur diesel fuel.