Citroën has launched a dual gas-petrol version of its GNV C3 super-mini in an experiment in the Haute-Garonne department, which offers owners the choice of running their car on, and refilling it from, natural gas supplied by Gaz de France and stored in a large compressor outside their home.

The special C3 has two fuel tanks, the other holding standard lead-free petrol, with a switch on the dashboard to allow a swift change from petrol to gas and back again. The gas tank has a range of about 300 kilometres, but as there are no gas filling stations or at present plans to build any, drivers who travel further than that from home have to use petrol until they return.

The fuel consumption is more or less the same whether using gas or petrol, so once the owner has invested in a gas compressor – it costs E500 to install and a modest E35 for an annual service contract with Gaz de France – he or she has a strong financial incentive to opt for gas. Petrol in France retails at about E1.20 per litre, whereas the charge for gas is only E0.80 a litre, two-thirds the price.

The alternative fuel is also highly beneficial to the environment. Exhaust gases are reduced by 20% and other gases produced, including carbon monoxide, carbon particles and nitrogen oxide, by at least 30% and some circumstances by as much as 70%. 

The Paris fire service is also taking part in a trial, testing a dual version of the GNV Berlingo, a Citroen used by its administrative staff. However there are no plans yet to convert fire engines to gas. A spokesman for the fire service said it would be unfortunate if a fire engine ran out of gas on an emergency call and for some reason the switch to petrol failed to work…