There is a government website that can help you find cheap car fuel in France. Cheap in comparative terms, at least. It provides information on petrol and diesel prices in all the different departments of the country.
Fuel Price Comparison website
The site is at Prix Carburants (petrol prices. Simply click on your department on the map (you’ll need to know the number of your department to get accurate information ) and a list of fuel stations will come up, giving their location and price.
Up to 8,000 of the country’s largest fuel outlets are involved in the program – slightly more than half the overall number – and are obliged to update their price information every day. The government hopes that by displaying their prices, it will encourage retailers to be more competitive.
The full site address is: www.prix-carburants.gouv.fr