I own a 2005 Toyota Corolla T Spirit 1.6. All evidence I find on fuel economy states 38-40 mpg, including your own "Real Mpg". I cover mostly motorway miles and have just calculated that I've done 50mpg, surely this can't be right?

I filled the tank up and subtracted the number of litres which were left in the tank from the amount I filled up last time and divided the miles by this amount, is this correct? I am basing this on the car having a 55 litre fuel tank.