Here is some trivia.....
The C4 has a switch on it's Centre Console to switch its instrument display from Metric to English and visa versa....
In "English", petrol consumption is displayed as MPG....
Now I am kinda old and still remember(and think in) MPGs as we used before 1974....when i want to compare fuel economy....
but it is important to realise that our OLD MPGs aint the same MPGs as being displayed in the C4 cos they use US gallons(3.78 litres) .... we used imperial gallons(4.54 litres)..... so our gallons will go farther...
so using the conversion tool on the following website... your C4 MPGs will probably improved by about 4 mpg on paper... but probably not in your back pocket....
http://tdiclub.com/misc/conversions.html