Do you use more gas on a full tank or a half tank?

Question

I hear from alot of people that you save more money on gas if you always fill your tank instead of filling it up every now and then. What do you think?

Answer 1

The weight difference isn't enough to lose sleep over,   but a full tank has less ability to vaporize fuel and less moisture laden air can fit to condensate water.  

Also,  to address vaporization,   fill your car slowly to keep from converting fuel to vapor before it is to be used.

Answer 2

You use less fuel on half a tank because your car is hauling less weight.

Answer 3

is not noticeable but full has more wight so car gotta make more power so it would use slightly more when full.

Answer 4

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.

Answer 5

i dont believe that. i use more gas when its only on half. i rather have a full tank and fill it up. i find myself filling up my tank more when its on half

Answer 6

Excellent question. It's the same with me , that  a full tank seems to last more, proporcionally of course...... But I don't find any possible reason for this. I think is more a myth.

Answer 7

I can save more gas with a full tank of gas than i can with 1/2 tank of gas.... i have a 1985 chevy scottsdale with a 350 v8 and its horrible on gas...once it hits 1/2 tank the gas just starts to disappear fast

Answer 8

It just seems that way because your fuel gauge goes past the full mark, so it makes you believe your getting more fuel from a full tank then a half a tank. weight has nothing to do with it

Answer 9

I drive a 97 neon and I can say that yes a half tank is better on fuel.

It is like driving around with an extra person in the car when you are on full.

I agree with all that gross weight stuff, but when you have a VERY small car, with a small engine, it adds up. Especially climbing hillls with the AC on and stuff...

Answer 10

less weight, but you have to be careful you don't run the tank dry because there is always a little bit of water in the tank and water is bad for the engine

Answer 11

I think the opposite is true.  A full tank is heavy than a half-full tank.  Extra weight means lower fuel efficiency.

hoogy below me gave the blondest answer ever.

Answer 12

I heard a full tank is better because there is less air in the tank that way, less air causes less evaporation of gas, especially when filling your tank.  I don't think you would get better gas mileage with a full tank vs. half tank

Answer 13

Less on half a tank but I prefer to fill up when the tank gets below the quarter full

Answer 14

Technically it should be the same, but from all the cars that I've had it always seems like the gas runs out much quicker once it's down half tank.  This is mainly because the gauges are rarely accurate according to the shape and dimensions of the gas tank on a particular vehicle.

Answer 15

if u fill it full it should last a while

Answer 16

I keep my tank full because I want to, not because I have some crazy ideas about saving money on gas.  I don't really give a c**p about the gas prices because they are not my fault.  There is plenty of oil in America that we could access to lessen the strain on foreign supplies but apparently we are more concerned with the friggin trees, as usual.