The EPA is interested in new technological developments which will reduce exhaust emissions and improve fuel economy. Because the development of the Fast Burn Engine System (NAPS-Z) by the Nissan Motor Company, Ltd., appeared to be a new technological development, the EPA requested a vehicle for testing and evaluation at the Motor Vehicle Emission Laboratory in Ann Arbor. Nissan Motor Company, Ltd., agreed to provide a vehicle for evaluation and agreed that the test program would include a variety of test conditions to enable a complete evaluation of the vehicle characteristics. The engine concept is the result of development aimed at meeting 0.41, 3.4 and 1.0 grams per mile for HC, CO, and NOx, respectively, while improving fuel economy. The conclusions from the EPA evaluation of the NAPS-Z can be considered to be quantitatively valid only for the vehicle used. However, it is reasonable to extrapolate the results from the EPA test program to other vehicles in a directional manner. It is reasonable to suggest that similar results are likely to be achieved where a similar engine concept is applied to other types of vehicles.