Comment by Glawen

Yes but the real feature that makes it viable, is that petrol station in France can change price only once a day. I forgot how it works in the UK, but in Germany they change wildly depending on the hour in the day. For example they show low price in the morning, so that workers who are late for work notice it and fill on the way back, only to find a price 10-20cents higher at 17h.