Six 1972 spark-ignited gasoline engines, used in trucks above 6,000-lbs GVW, were subjected to baseline exhaust emissions tests. Two groups of three engines, representing various cylinder configurations and displacements were tested by the current 1972 Federal test procedure. The concentrations were then converted to a mass emissions for the nine-mode schedule using the 1974 FTP applicable to heavy-duty gasoline engines. One popularly used V-8 engine from each manufacturer's group was subjected to a limited series of laboratory tests to demonstrate control device effectiveness. This part of the study was restricted to the use of light-duty items of laboratory-type approaches because of the apparent lack of technology for gasoline engines in heavy-duty service. Substantial reductions in all emissions were effected on both engines with a combination of exhaust gas recirculation, air injection and an oxidation catalyst with some increase in fuel consumption.