text: How To Calculate Your Fuel Consumption
  You won’t know if your new driving style and skills are working unless you know the average miles per gallon (mpg) of your car. Some cars have on-board computers, but they are not always accurate.
  When you fill up your car, fill the tank to the top and simply make a note of:
  - Your mileage since the last fill
  - The number of litres of fuel you put in
  - The cost per litre of fuel
  Then simply use the fuel consumption calculator below:
  Or, to work it out yourself:
  - Fill your tank to the top
  - Zero the trip counter
  - When you next fill up, note the mileage driven
  - Fill the tank again and note the number of litres put in
  - Divide the number of miles driven by the amount of fuel used in litres (miles per litre)
  - To convert the figure to miles per gallon multiply it by 4.544
  Frank does stages one and two above. His trip meter reads 160.1 miles when he next fills up. It takes 22.3 litres to fill his tank. Frank works out that his fuel consumption has been:
  160.1 divided by 22.3 = 7.179 miles per litre.
  This is 7.179 x 4.544 = 32.62 miles per gallon.