Bear in mind that the gallon we use is different from the US gallon, too:
- a UK gallon is eight (imperial) pints of 20 fluid ounces, so 4.54 litres
- a US gallon is 231 cubic inches, so 3.79 litres
The reason that I thought American car fuel economy was so terrible as a child is partly because UK mpg is +20% on US mpg for the same car on the same fuel. But also, because American car fuel economy is so terrible.
Ah yes. I remember preparing a recipe once that included frying up the ingredients in a cup of oil, and that turns out seriously fucking greasy if you use the UK cup size.