In 2012 the French Government introduced legislation making it compulsory for all vehicles to carry a breathalyser whilst travelling in France. A fine for non-compliance was due to be introduced in 2013 however this was postponed indefinitely by the French Government. It is still recommended to travel with one. Breathalysers must conform to French standards denoted by a 'NF" number. A French rental car should come equipped with all required safety equipment including the breathalyser but check this before leaving the rental location. If you need to ask for a breathalyser, you're after "un éthylotest", pronounced eh-teel-oh-test.