How to work out your MPG

How to work our your MPG (miles per gallon). With the rising costs involved in motoring it is handy to know what your current MPG is. It also incicates the condition of the car, poor mpg will often indicate there is an underlying issue with your car.

Some cars come with a trip computer that approximates your fuel consumption but there is no substitute for a manual full tank calculation.

To use this fill your tank to the brim. When you get to empty, note your miles and how many litres it took to fill the tank back up and put them in the calculator below (-source

It is suprising what things can affect your MPG. The top problem areas are…

1) Driving style, using full throttle, high rpm and doing lots of heavy braking. Also driving too fast uses a lot more fuel than your would at slightly slower speeds.

2) Car maintanance. Checking the oil level, tyre pressures and state of the air filter can all boost your MPG. Running on dirty spark plugs can also mean you are wasting fuel. Tyre pressures are one of the biggest areas here and should be checked every 2 weeks. Run pressures nearer your cars upper recommendations for MPG although this may have an impact on tyre wear if you go too hard. Wheel bearings and wheel alignment can all have a detrimental effect on your MPG calculations.

3) Weight, carrying a lot of junk around will be wasting fuel. It takes a lot more power to push a heavy car along and you don't need half the stuff stashed in the back of your car.

4) Using airconditioning, heaters and other electrical functions. All these drain power from the battery and air conditioning is one of the heaviest drains. Use the hottest aircon setting you can comfortably get away with. Use recirculate on really hot days to lessen the load of cooling the hot outside air and open your windows at slower urban speeds.

Some people think that driving really slowly saves fuel and changing gear as soon as you can is good. IT IS NOT, Find the optimum RPM band and keep the engine in that. For most cars this is somwehere between 2000 and 3500 rpm.

If you want to work out your MPG manually just divide the distance covered by the litres used. Then convert the litres to gallons by dividing the litres by 4.5461 (1 UK gallon = 4.5461 litres).

Please use the feedback box below to pass on your own fuel saving tips for our readers.