Vegetable oils are green promising alternative fuels for diesel engines such as jatropha oil. When they are used in diesel engines, higher viscosity and lower volatility of vegetable oils causes problems in spray penetration, atomization and mixture formation. Blends of biodiesel and diesel oil by volume (B5, B20, B40, B70 and B100) are burned. We produced biodiesel with standard chemical and physical properties. A new biodiesel engine should be designed to burn biodiesel blends up to B100 according to biodiesel thermodynamic cycle is needed. Conventional diesel engines are not suitable to burn biodiesel efficiently. Combustion and characteristics of biodiesel and preheated oil are extensively furnished. Burning biodiesel reduces emissions of CO, CO2 and HC. Suggested biodiesel engine should be designed to reduce NOx. This book can be useful for engineers, researchers, technologists seeking biodiesel production, environmental scientists, and car manufacturers.