You know that your wet gallon is short, right? You claim 3.78 litres when in reality they're 4.54 litres - it's like the gas station short-sells you every time you go!
Strange thing is your dry gallon is (as near as makes no difference) is the same as everyone elses wet gallon, and considerably larger than your dry gallon.
Next time you buy fuel ask the attendant for the price of a dry gallon - if you can be motivated, also take a photo of the look of confusion when you ask and post it up here for Ss&Gs