Please correct me if necessary.
Initially, my intuition tells me to add the odometer reading from the moment of fueling. But even in the tutorial in the second video here:
https://www.fuelly.com/about/ you show the same thing, to note the odometer reading from the moment of fueling.
But this procedure creates an incorrect calculation.
Let me give you an example from my Mazda. You find it on the profile.
On June 2nd, I filled 36.65 liters for 132,065 km
On June 15, I refueled with 38.29 liters at 132,406 km.
132,406 - 132,065 = 341 kilometers.
This means that I did 341 km with the filling done on June 2 (and not with the one on June 15)
That means 36.65 * 100 / 341 = 10.75 liters / 100km (and not 38.29 * 100 / 341 = 11.23 liters / 100km as this site says)
Am I doing something wrong?