Exhaust manifold thermal reactors, exhaust gas recirculation, exhaust particulate trapping systems, and appropriate engine adjustments have been combined to produce total emission control systems which reduce all gaseous and exhaust particulate emissions from passenger vehicles. The first generation system was developed to meet the former United States and State of California emission standards for 1975. Field service tests demonstrated that the emission standards were met, but unexpected operational problems were encountered. Solutions to these problems have been found.Second generation total emission control systems are being developed in an attempt to meet the current United States emission standards for 1975 - 1976. These systems in their present state of development produce very low exhaust emission levels; the hydrocarbons are well below the standards and the carbon monoxide and nitrogen oxide levels are quite close to the 1975 - 1976 standards. Possible approaches to reduce the emissions even further and alleviate partially the losses in fuel economy are discussed.