The number of compressed natural gas (CNG)-equipped vehicles has doubled in Pakistan during the past year, having risen to about 30,000. This trend of conversion of petrol/gasoline-driven cars to CNG reflects the increasing popularity of the low polluting, economical and indigenous fuel among the users. The Hydrocarbon Development Institute of Pakistan (HDIP) introduced the CNG technology in the country on an experimental basis by establishing two outlets at Islamabad and Karachi.