Abstract The dwindling of natural resources such as crude oil, coal etc. has made it essential to switch over to biodiesel. Biodiesel has a number of properties which are beneficial to the environment. The main advantage of biodiesel is that it's carbon neutral and it does not create carbon dioxide (CO2). In addition, it leads to a decrease in pollution by reducing the emission of harmful and hazardous substances to the atmosphere and greatly improves the engine performance. This paper puts forward a comprehensive assessment of biodiesel production from various non-edible oils such as waste fried oil, pyrolysis oil, preheated palm oil, waste cooking oil, jatropha oil, karanja oil etc. It also serves as an index to measure combustion, performance and emission characteristics in a variable compression ratio (VCR) diesel engine, where biodiesel is blended with diesel. The need for switching over to VCR engine is that it provides better fuel efficiency, up to 30% reduction in fuel consumption, better control at peak cylinder pressure, ability to use multi-fuel and reduction in the exhaust emissions when compared to that of a constant compression ratio diesel engine.