Gentlemen, after 2 years of wondering, it's finally solved: Why do the CFM engine variants of the Airbus 320 family planes have much shorter ranges than their IAE siblings and why does fuel seem to mysteriously disappear from the EFOB part of the MCDU? Here is the reason:   The CFM engines eat TWICE as much fuel as the upper and lower ECAM show. In fact, the upper and lower ECAM fuel flows are LIES. At best they are just estimates of what the fuel flow should be. THEY ARE NOT REAL TIME