Spark ignition engines are responsible to a considerable extent for the major pollutants that are emitted in the atmosphere. The interest of researchers in the development of oxygenated fuel extenders has increased in recent years due to the removal of lead compounds from gasoline in combination with the need to reduce the components with high ozone-forming potential, i.e., aromatics and olefins. The purpose of the current work was to investigate the ignition quality of compounds derivable from renewable sources (furan derivatives and p-cresol), their effects on regulated emissions from conventional spark ignition engines, and their effects on gasoline properties. It was found that furan derivatives and p-cresol are very effective antiknock compounds, thus allowing a reduced aromatic content in gasoline without any further negative effects on gasoline properties. Hydrocarbon and CO emissions were found to be a function of the air-fuel ratio (AFR) and independent of engine loading, whereas NOx emissions appeared to be affected not only by AFR and load but by the fuel＇s nitrogen content as well. Fuel NOx predominated over thermal NOx under low engine loading conditions. Moreover, 2-methylfuran, furfurylamine, and p-cresol reduced HC and CO emissions relative to base fuel even at the same AFR level, whereas the effects of the compounds studied on NOx emissions were dependent on the engine operating AFR level and on the nitrogen content of the fuel.