Of course, one needs to know what needs to happen in terms of payload and range for those figures to occur. If they are based on 555 pax at 8000nm, flying 450 might affect those numbers a bit. Afterall, I imagine she can't carry 100 people 5000nm on only 150,000 liters of fuel.

Also, that is what Airbus said it would do based on modeling. Now I have not heard any reports from her flight-test regimen stating she uses a lot more, but then I also haven't heard any saying she uses 3 liters or less, either.

Of course, the same speculation applies to the 787, the A350, and the 748 until they too enter testing and, in reality, service.