Compressed Natural Gas (CNG) is a substitute for gasoline (petrol) or diesel fuel. It is considered to be an environmentally "clean" alternative to those fuels. It is made by compressing methane (CH4) extracted from natural gas. It is stored and distributed in hard containers, usually cylinders.

Green fuel -
Commonly referred to as the green fuel because of its lead and sulphur free character, CNG reduces harmful emissions. Being non-corrosive, it enhances the longevity of spark plugs. Due to the absence of any lead or benzene content in CNG, the lead fouling of spark plugs, and lead or benzene pollution are eliminated.

Increased life of oils -
Another practical advantage observed is the increased life of lubricating oils, as CNG does not contaminate and dilute the crankcase oil.

Mixes evenly in air -
Being a gaseous fuel CNG mixes in the air easily and evenly.