From 1 July 2012 year all drivers visiting France will need to carry a breathalyser kit in their cars. From November 2012 there will be an €11 fine for not complying with this.
With a start date for the new measure of 1 July 2012, the rules will apply for anyone travelling to or through France by car on a tour, perhaps on the way to a track day, or just on holiday or business.
Single-use breathalyser kits will satisfy the requirement. The legal limit in France is 50 mg per 100 ml of blood. They cost between€1 and €2. It is intended that people will be able to test themselves to check whether or not they are over the French drink-drive limit.
If you are stopped you may be required to provide a test – using your own equipment. So you are advised to have at least two breathalysers at all times, so that if one is used you still have one to produce for the police.