You're spot on with the mental models. If I try to imagine a gallon, I think of 2x2L bottles, one of them not quite full. A pint and I imagine a 600mL soft drin

You're spot on with the mental models. If I try to imagine a gallon, I think of 2x2L bottles, one of them not quite full. A pint and I imagine a 600mL soft drink or water bottle. When you start having to do double conversions (eg miles per gallon) it becomes hopeless - that means nothing to me - and I have to convert to l/100km. These "intuitiveness" arguments are silly. It's whatever you're used to. So with that realisation, we may as well choose the more universally self-consistent and useful system, which is indisputably metric.