And will it be CNG or LPG? is a question customers lining up at, believe it or not, car showrooms may soon be asked. The use of liquified petroleum gas (LPG) as auto fuel is to be authorised soon and competition with the other green fuel Compressed Natural Gas (CNG) is hotting up. CNG has a head start in India over LPG since it is being promoted for the past five years by the public sector Gas Authority of India Ltd (GAIL) in Mumbai and Delhi.