Technological improvements might also involve the adoption and use of alternative fuel or alternative propulsion vehicles. In developing countries, the most commonly discussed alternative vehicle strategies include compressed natural gas (CNG), liquefied petroleum gas (LPG), alcohol-based fuels, and electric propulsion or hybrid -electric vehicles in certain applications. Other alternative fuels showing potential long -term promise in the transport sector include hydrogen fuel cells and various synthetic fuels for use in compression-ignition engines. Rate of change of technology in the vehicle fleet. An extensive review of appropriate technologies in the emissions-reduction literature and at conferences can often.
