Keygrip,
I ran CFPs for a C550, 1.40hr sector.
PLD / FUEL BURN / %
500 / 686 / 4.2%
600 / 693 / 3.6%
700 / 699
So for every 100 additional KGS, its costing me circa 4% to carry. But the amounts of fuel increase are so small that they arent worth worrying about.
So to answer your original question, all aircraft burn more fuel to more fuel to carry fuel. you only need to worry about it when the financial costs are sufficient that they impact on your operation......
Mutt