The distance-per-energy is numerically backwards compared to the energy-per-distance.
This is important when e.g. wondering which car to replace, calculating a fleet average consumption and so on and so forth.
For example: "Which saves more gasoline, going from 10 to 20 mpg, or going from 33 to 50 mpg"?
There is good reason that the rest of the world uses the opposite system, and the reason isn't just that no one else uses gallons. It's that it's an objectively worse way of communicating fuel consumption in every single way that matters.
>> "Which saves more gasoline, going from 10 to 20 mpg, or going from 33 to 50 mpg"
I'm surprised such questions come up often. Usually a current vehicle gets x MPG and a new one might get y. We use l/100 km in Canada. I think the primary advantage is it relatively easy to compute number of liters needed on a longer trip. It isn't super important however - better just to fill up!
PS
I was mostly kidding about using MPJ. The numbers would be tiny and hard to make sense of.
For example: "Which saves more gasoline, going from 10 to 20 mpg, or going from 33 to 50 mpg"?
There is good reason that the rest of the world uses the opposite system, and the reason isn't just that no one else uses gallons. It's that it's an objectively worse way of communicating fuel consumption in every single way that matters.