Volatility: volatility depend upon fractinal composition of fuel. Method of measuring volatility has been standardized by ASTM ( American society of Testing Materials) and the graohical representation of the result is generally referred as ASTM distillation curve.
Vapour Lock characteristics: High rate of evaporation may cause vapour lock and stop fuel supply. It must be compromise between contradictory requirements.
Octane Rating: The octane rating of a specific gasoline is measured by using it in a single-cylinder test engine with a variable compression ratio and adjusting the ratio to produce a standard knock intensity as recorded by an instrument known as a knockmeter. By comparison to tabulated results from similar testing of various mixtures ofisooctane and n-heptane at the same compression ratio, the octane rating of the gasoline is determined.
Vapor pressure: The vapor pressure of a gasoline is a measure of its propensity to evaporate (i.e., its volatility) and high vapor pressures result in high evaporative emissions of smog-forming hydrocarbons which are undesirable from the environmental viewpoint
Sulfur content :When gasoline is combusted, any sulfur compounds in the gasoline are converted into gaseous sulfur dioxide emissions which are undesirable from the environmental viewpoint. Some of the sulfur dioxide also combines with the water vapor formed when gasoline combusts and the result is the formation of an acidic, corrosive gas that can damage the engine and its exhaust system.
Storage stability: Gasoline stored in fuel tanks and other containers will, in time, undergo oxidative degradation and form sticky resins referred to as gums. Such gums can precipitate out of the gasoline and cause fouling of the various components of internal combustion engines which reduces the performance of the engines and also makes it harder to start them. Relatively small amounts of various anti-oxidation additives are included in end-product gasoline to improve the gasoline stability during storage by inhibiting the formation of gums.