A CNG car is a vehicle that runs on compressed natural gas (CNG) instead of gasoline or diesel fuel. The engine of a CNG car functions in the same way as a gasoline-powered combustion engine. Natural gas is stored in a fuel tank, typically at the back of the vehicle, and transferred through fuel lines to the engine. A pressure regulator reduces the pressure of the gas to a level compatible with the engine fuel injection system, and the fuel is introduced into the intake manifold or combustion chamber, where it is mixed with air and then compressed and ignited by a spark plug. CNG vehicles are considered safer than gasoline-powered ones.

CNG vehicles are becoming more common worldwide, and major carmakers are manufacturing more vehicles that run on CNG. CNG vehicles are common in South America, where they are mainly used as taxicabs in main cities of Argentina and Brazil. CNG buses are also operating in other major South Korean cities like Busan, Daegu, Daejeon, Gwangju, and Incheon. CNG vehicles are good choices for high-mileage, centrally fueled fleets because they can provide similar fuel range support for applications that stay within a region supported by reliable CNG fueling. The advantages of natural gas as a transportation fuel include its domestic availability, widespread distribution infrastructure, and reduced greenhouse gas emissions over conventional gasoline and diesel fuels.