Full Use Else Lose
IMO, I have found the reason stated above.Initially FE shown on the meter is higher and then it gradually reduces, not sure of the reason.
MID calculates Avg FE in correlation with the tank capacity. Fuel used divided by number of KMs clocked.
Hence, difficult to increase it when tank is going empty.
INST FE displays the fuel consumption right at that very moment depending on how hard/sane are you driving.