Originally Posted by myrt1987
I mostly notice it with 1/4 tank or less it takes more gas to maintain the same speed. I cant explain it myself.
It's not that your car is consuming more gas when you get down to the last 1/4 tank. It's that the tank is tapered on the bottom, so the bottom portion of the tank holds less volume that the upper portions of the tank. It has nothing to do with momentum, weight, consumption of gas, and so on.
And the main reason many people fill their tanks at around the 50% point is to avoid the accumulation of condensation in the tank. This is most important in the winter time.