And the rest of the civilized world.

(Sorry, I just like the SI system of units.)

It can be confusing in the UK where economy is usually quoted in mpg whilst petrol is sold in litres.

Actually I think the Imperial system is better in this case. I find it easier to remember a number which is an integer in the 20-40 range than a real between 5 and 10.

I find that in my mind, most of the relevant numbers tend to get rounded up to "a bit less than ten" anyway.

Only for you - and only for the current state of efficencies.