Gasoline is not cheap. Ask anyone, running out of gas especially at night when on a highway when its dark is horibal. It is dangerous to so that is why you try to stay filled up. Gas is not the only expens. But what about cloths, and you need some money to go out.
Gas is all ready to expensive, why make it more.
Added to all the other things it can mount up. For example, school books and fees. You have to make up a budget and stick to it. Give yourself room for one fillup a week, that's it. You have to save money aside for books, food, ect.