Does the average fuel consumption of a 2013 model recalculate every day? I don't understand, I bought a second-hand one.

The displayed fuel consumption number is the average fuel consumption for the segment of the journey. It resets after parking for half a day. The adjustable horizontal bar in the middle represents the instant fuel consumption, which varies during acceleration, cruising, etc.

This calculation isn't accurate... You just calculate how much money you spent at the gas station and then how many kilometers you drove.