This can usually be done by holding down the little peg next to the display.
Check your car's owner's manual for more information on resetting the trip meter.
Divide the since resetting the trip meter by the you just filled up (found on the receipt).
This will give you your car's kilometers per liter (km/L) since you last filled up your tank. Example below:
Multiply the found in step #2 times the difference in your and the you just filled up:
|NOTE: This calculation is a best-estimate at your remaining milage once your gas light has come on. Continually driving on too low of fuel can damage your fuel pump and should be avoided.|