Why is it cheaper to completely fill your tank in one go than to fill it in small increments over a long period of time?

Question

I don’t know if it’s true but it’s what I have been told by a few different people.

In: Economics

Answer 1

A gallon of gas weighs about 8 pounds. A 15 gallon gas tank @ 1/2 full would save 60 pounds vs a full tank. Or 2% of the weight of a 3000 pound car. If you think this will make a difference, you should really be freaking out if you have passengers in your car. Or if you decide to bring a back pack, or perhaps a long book.