We measure liters used on 10 km like you say mpg 
Checked my airfilter today and it was very dirty,so I hope it helps to clean it.
Every time I fill up I do a check of how many km driven and how much diesel used.
Gasoline and diesel are expensive in Norway around $ 7 for 1 gallon
I thought it was liters per 100km........
So with the shorter distance, I thought that was all you were travelling.
