breakfastburrito,
Senior management could not get their heads around the fact that there was essentially a FIXED fuel burn for an empty aircraft, and then a small additional fuel burn per full seat. Management assumed fuel burn was essentially a linear function. In other words if QF had a 650 seat config the fuel burn would indeed be 30% less than the -400, but not in a 450 seat config. This remember is many months after the introduction of the aircraft.
Apologies for my skepticism but it sounds like an urban myth to me, but if you're convinced it's true I'd like to know who the 'senior management' were, any chance you can PM me?