The primary purpose of writing this book is to make available to the students, researchers and is prepared for case study projects. This book deals with the utilization of diethyl ether (DEE) as an oxygenated additive to diesel and other alternate fuels such as LPG and Palm Kernel Methyl Ester (PKME) in direct injection diesel engine. In this book the detailed report and it investigates the utilization of diethyl ether (DEE) as an additive to the diesel, LPG and bio-diesel, which makes as an alternative fuel for diesel engine and the performance and emission characteristics are calculated. The advent of this book is to prepare the alternative fuel to replace conventional diesel fuel in the CI engine to meet emission regulations as per standards without affecting the performance.