If the fuel warning light didn't come on I think it could be regarded as a fault, really it's an indicator and no more. It reminds you that you have 5,6,7,8 or 9 litres of fuel left. you can then do your own calculations as to how soon you need to top up. I would sooner know I needed to think about refueling rather than run out because there was no indication. Driving in France which i often do where the fuel price between supermarkets and motorways is some 15 cents different with supermarkets often off the beaten track it allows me a level of reassurance that I have fuel to drive to a convenient supermarket and not pay motorway prices. Obviously as shown here not every warning light comes on at exactly the same time but with shallow fuel tanks and surges because of hills that's to be expected, but when you know your car you can make your own decisions.