I think maybe the confusion is around the idea of a
fuel-up. The idea of a fuel-up here at Fuelly is that it corresponds with a trip to the fuel pump. So at Fuelly you enter your odometer reading at the time of the fuel-up and the amount of fuel you put in your tank. Then Fuelly calculates the distance you drove since your last fuel-up based on your previous odometer reading. It's not really going to work any other way.
So you can't, for example, enter an odometer reading and tell Fuelly you used 1,000 litres or gallons to get there. Each fuel-up here corresponds to an individual trip to a fuel pump. We do that because we calculate individual fuel-up fuel economy by using the
difference from full. Here's more info about that:
Why do I have to fill the tank all the way up every time I buy fuel?
__________________