The diesel passenger car offers a substantial advantage Particulate production involves an incompletely unin fuel economy over its gasoline-powered counterpart, derstood series of phenomena that includes nucleation, hut the long-range future of the diesel in this application surface growth, agglomeration, dehydrogenation, oxiis threatened by future federal standards on exhaust dation, and adsorption and condensation of gaseous particulate emissions. These particulates are primarily hydrocarbons. The contemporary state of understandcombustion-generated carbonaceous soot in combinaing of these events is reviewed as they apply to the tion with a solventextractable hydrocarbon fraction. passenger-car diesel engine.