The following result is obtained by our Internet research Algorithm: Petrol is made up of hydrocarbons (mainly paraffin, naphthenes and olefins) which comes as a product of reformer or catalytic cracker. Crude oil which is composed of big hydrocarbons is broken into tiny molecules. Petrol which is extracted from the crude oil, some additives are added into it to enhance the quality of the fuel to minimize the carbon build-up inside the engine, better quality fuel improves combustion. The quality is measured in RON (Research Octane Number), the more RON, the better fuel it will be. Better quality fuel keeps your engine and healthy clean but doesn't provide much difference in mileage. The difference can be seen of additional 1-2km/litre that will in case of a very long run.