46.5l is 10.22857 gallons.
275 miles range is 26.9mpg.
Your current long term average mpg figure from the computer is used to calculate the range to empty.
I'm guessing it reads 26.9mpg

Actual mileage achieved is of course variable.
If you had a GTD, it would probably show you 400+ miles range.... you and your greenhouse gas machine
