Dunno where you can download a manual, but if you have a trip computer, you will have current and stored mpg. On your right stalk (wiper stalk) there should be a slide button with - 0 1 2 0. 1 is the current or trip and will reset after about an hour of being switched off, and 2 is stored, so will give you an avarage of total since last reset. the 0 each side is spring loaded and will reset whichever one its next to. The button on the end of the stalk is to switch between options on trip ie, clock, miles, oil temp, mpg, etc etc........