It’s hardly surprising that car manufacturer’s official MPG figures do not give an accurate indication of real fuel economy performance. The figures are obtained by technicians gently driving cars on a rolling road in a lovely warm laboratory. Calculate your own real MPG figures from driving on real roads in the real British weather and see how they differ!

Our simple test will provide you with an accurate real MPG figure for your car, helping you to work out the real running costs.

Many cars have ‘on board computers’ that provide an MPG figure, however these are not particularly accurate (there’s a surprise!) The best way to get an accurate MPG figure for your car is to measure it yourself. It is very easy to do, just follow the steps below:-

• Step 1: Fill your tank up – as much as you can get in the tank before the fuel pump cuts out. Set your trip mileage counter to zero (or note your total mileage) before leaving the petrol station.
• Step 2: Drive as normal until the fuel light comes on saying you need to fill up again, or the tank is a quarter or less full.
• Step 3: Fill up the tank again, right to the brim as before. Make a note of the exact amount of fuel it takes to fill up the tank (this will be on the receipt) and also the number of miles since you last filled up.
• Step 4: Enter the two figures into our on line calculator to the right, click "show result" and record the number.

You can do this test more than once, in fact the more times the better, as you will get a better indication of your real MPG. For instance, if the first time you did the test you were mainly driving in and around town on short journeys, you will get a good indication of your ‘urban’ MPG. However if you are going on a longer motorway journey one day, fill up and do the test again so that you get an idea of your ‘extra-urban’ MPG.

Anything else I should do?

To compare with the manufacturers data do not do the test with roof racks, boxes, bikes or trailers on your car as the reduced aerodynamics and increased weight will reduce MPG quite a lot. Other than that just do your normal driving. However when you enter your figures in the calculator please consider the main type of driving you were doing during the test:-

• Urban: Mainly (at least 80% of the time) in and around town in 30mph zones.
• Open road: Mainly (at least 80% of the time) on A roads and motorways in 50 - 70 mph zones
• Mixed: A mixture of urban and open road driving