fuel needle

My fuel needle seems to not display the right amount of gas that i have left in the tank. I'll start the car and it'll be like quarter tank full but then after 5 minutes of driving it'll drop to like half of my quarter tank. I'm wondering if there's something wrong with it or is tat normal. Also what can i do to get better mileage out of my car. I get like 250 miles max out of a tank of gas. thanks.

It is quite possible that the float in the fuel tank has gone bad and is not properly indicating the amount of fuel. The level indicator is part of the fuel pump assembly and it is possible to change just the indicator and the fuel level sending unit connected to it but you must remove the fuel pump
to do the repair.

ohhh...thanks...that sounds like a lot of work too but would u be able to explain step by step?

It would be difficult to explain. I would go purchase a chiltons or other manual for your car as it should be able to explain it easier than I can.