CNG is a fuel gas which is mainly composed of methane that is used for vehicles in general. Here CNG stands for:

Composition and Benefits Main Component: It consists primarily of Methane ($CH_{4}$), usually ranging from 80% to 95%.Storage: It is stored in thick-walled cylindrical tanks at a pressure of about 200–250 kg/cm².Environmental Impact: It is considered a "clean fuel" because it produces fewer harmful emissions (like carbon monoxide and nitrogen oxides) compared to traditional fossil fuels.