In this book, the authors present and discuss the characteristics, performance and environmental impacts of diesel fuels. Topics include the effects of diesel fuel composition and properties on engine performance and pollutant emissions; biodiesel production from alternative feedstocks in Brazil; development of dual fuel combustion models for direct injected heavy duty diesel engines; the molecular properties of some diesel fuel components and their biodegradation; the effect of oxygen additives on the performance and combustion of diesel engines; contrasting the life-cycle performance of conventional and alternative diesel fuels; and the impact of ethyl-tert-butyl ether (ETBE) addition to diesel oil.