you are viewing the TRIP A mileage meter,
i mean if you are on the ODO display, and
you press MODE button once -> goto Trip A
again MODE button -> goto Trip B
again MODE button -> goto Trip A mileage (thats what you are viewing)
again MODE button -> goto Trip A Average mileage ( that shows the average mileage you are looking for)
the one you are viewing changes from 0.0 to 99.9 km/ltr, that is actually showing the mileage you can achieve if u remain at same acceleration, same gear, same speed.
means it calculates the mileage according to that particular time instant's speed, acceleration, gear, etc.