Register a free account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members through your own private inbox!
If you have the option there is a button on the right stalk (that controls the wiper speed) press the button at the end of the stalk and if you have a trip computer it should cycle through to MPG.
Once you know the number of miles you've done and the number of litres of fuel used its a simple calculation, no need for any websites.
Divide the number of liters of fuel used by 4.546 = Gallons (eg 25l / 4.546 = 5.5gallon)
Divide the number of miles travelled into the gallons figure = Miles per gallon.
Calculators work out cost per mile and stuff too which is pretty cool (I know you could do this manually too, but why make life harder than It needs to be?)