[dcb]

Not in stock form,
but you can certainly calibrate the fuel usage in liters and the mileage in kilometers. Just pretend that it says liters instead of gallons and kilometers instead of miles.

Then all your usage will be in terms of K/L

Then add a function to convert k/l to l/100k and wrap all the displayed mpg values in it. I can take a stab at that if nobody else wants to.