connections to  piped -in  public utility  services, or with portable grills . Transportation CNG is a cleaner alternative to other  automobile  fuels such as petro) and  diesel . As of 2008 there were 9.6 million  natural gas vehicles  worldwide, led by  Pakistan  (2.0 million),  Argentina  (1.7 million),  Brazil  (1.6 million),  Iran  (1.0