How does natural gas compare to gasoline?

Natural gas is lighter than air. If a leak were to develop, the gas would rise and disperse through the atmosphere giving little chance for ignition. Compare that to gasoline and diesel fuel, both of which are dense liquids that tend to pool and are easily ignitable. When CNG is burned in the engine, it produces low emissions. This means less smog, less air pollution, and cleaner air. This makes CNG a promising motor fuel for the future.