A Hybrid Exhaust Gas Recirculation (Hybrid EGR) is proposed. In this system the exhaust gas of a gasoline engine is mixed with the intake air of the diesel engine. The Hybrid EGR system eliminates the adverse effects of conventional diesel engine EGR systems on particulate formation, engine performance and durability. The application of a Hybrid EGR system to an experimental single cylinder diesel engine reduced NOx emissions to one-third the level produced by the same engine without EGR. These results were achieved with a Hybrid EGR dilution ratio of only 10 percent by volume without any particular increase in smoke emissions. Simulation results of a practical system application to motor vehicles are discussed. It is predicted that the new system will reduce vehicular diesel NOx emissions by one-half, without increasing the smoke level or adversely affecting fuel consumption.