Compressed natural gas (or simply shortened as CNG) is a fuel gas mainly composed of methane (CH 4), compressed to less than 1% of the volume it occupies at standard atmospheric pressure. It is stored and distributed in hard containers at a pressure of 20–25 megapascals (2,900–3,600 psi; 200–250 bar), usually in cylindrical or spherical shapes.

Innovations in CNG Vehicle Technology: Vehicle manufacturers have made significant strides in CNG engine technology, enhancing efficiency and performance. Modern CNG vehicles feature optimized combustion processes and advanced fuel injection systems, reducing emissions and improving fuel economy.

The engine functions the same way as a gasoline engine. Natural gas is stored in a fuel tank, or cylinder, typically at the back of the vehicle. The CNG fuel system transfers high-pressure gas from the fuel tank through the fuel lines, where a pressure regulator reduces the pressure to a level compatible with the engine fuel injection system.

CNG is used in traditional petrol/ internal combustion engine vehicles that have been modified, or in vehicles specifically manufactured for CNG use: either alone (dedicated), with a segregated liquid fuel system to extend range (dual fuel), or in conjunction with another fuel (bi-fuel).