50-60 miles per U.K. gallon. Or 11-13 miles per litre.
20 miles per us gallon is terrible, but it’s more like 25 miles per U.K. gallon, which isn’t much below what by 1984 Nissan mid sized car used to get 27 years ago.
I tend to use 45mpg/10mpl now, as both my old micra and my newer Skoda got about that. That’s about 37mpg (us).