In Switzerland there is a significant interest to use natural gas as a vehicle fuel. This interest stems from both a desire to reduce the environmental pollution caused by automobiles and a wish to diversify the sources of energy supply. The current “state of the art” natural gas technology is very cose to meeting the emissions levels required for vehicle homologation however further development of the carburation and electronic control systems as well as catalyser technology is necessary to ensure a margin of security for future emissions standards. Despite offering sunstantial advantages relative to petrol, the utilisation of natural gas is currently penalised by antipollution legislation which does not test the full range of vehicle operating conditions and which fails to take into account the most recent scientific knowledge, particularty that relating to hydrocarbons.