Six 1972 spark-ignited gasoline engines, used in trucks above 6,000 lbs. gross vehicle weight, were subjected to baseline exhaust emissions tests. Two groups of three engines, representing various cylinder configurations and displacements were tested. The emissions of interest were unburned hydrocarbons, oxides of nitrogen, carbon monoxide and aldehydes. 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. The experimental multi-modal test procedure was employed to evaluate various control strategies such as basic spark timing, carburetion, air injection, exhaust gas recirculation and an oxidation catalyst singly and in combination. (Modified author abstract)