As for better fuel economy because there's less weight in the tank, it's hogwash. A car weighs a minimum 2000 pounds and the upside is unlimited, but let's say 6000 pounds. Now, a 20 gallon tank of gasoline weighs about 6 to 6.5 pounds per gallon, for a total weight of 120-130 pounds. This means a tank of fuel represents at most, 6.5% of a vehicle's gross weight and can be as low as 2.2%. This is for a full tank, mind you. It's about equal to saying when you have an additional friend in the car, you get worse gasoline mileage. Not very likely, is it?
Keep in mind, a half tank is half of those numbers, and by weight, it's equal to a 3rd grader. I try to fill my tank whenever prices drop. This way, I'm saving money if it goes back up. If it goes down again, I simply fill up again. This way, I save as much money as possible. I don't worry about a few pounds for gasoline. I just can't be bothered pulling off the road to fill up only half my tank. I'd rather fill it and be done with it for as long as possible.
· 1 decade ago