Converting an automobile with a gasoline-burning engine to one that can also run on compressed natural gas requires a new fuel system and a few additional engine control components. The fuel components include a new fuel tank, a regulator to manage the tank's pressure, a secondary fuel injector and an adapter. Additionally, two new wiring harnesses and a new fueling computer need to be added. Other than these parts, the vehicle and its engine can be left the same.
The compressed natural gas fuel tank must withstand the same standards for impact and puncture resistance as an under-car gasoline tank. However, it must also meet significantly higher strength standards. CNG fuel tanks are typically made of aluminum, steel or plastic and may include carbon-fiber, fiberglass or other composites.
Unfortunately, the fueling options for a CNG car are minimal. As such most owners of natural gas cars purchase compressors to allow them to fuel up using the natural gas delivered to their homes. Even with this setup filling a car's CNG fuel tank can take up to 22 hours. As a result of these issues, many natural gar car owners opt to install their CNG systems in parallel with their existing gasoline systems.