MPG explained

MPG explained

When you’re shopping for your next car, there are loads of things to consider – and one of them might be the MPG (miles per gallon) figure.

All of the cars on our website have their MPG figure listed in the “Key Facts” section – so you can go ahead and make an informed choice at CarShop!

What actually is MPG?

MPG is simply a way to measure the fuel-efficiency of a vehicle, by working out how many miles a car can travel with only a single gallon of fuel in the tank.

How is MPG calculated?

The MPG figure you see when you purchase a car is worked out under strictly controlled conditions in a lab, using a test called the WLTP (World Harmonised Light Vehicle Test).

Read more: WLTP explained

The WLTP was only introduced for new cars in 2017. It involves additional tests, real-driving data and greater consideration of how cars perform outside the lab, so it’s far more accurate than the previous test, which was called the NEDC.

By testing each vehicle across four different driving speeds, the WLTP gives a clear picture of how cars perform on main roads, in cities, suburbs and on the motorway. The results of these four tests are then compiled to give you one solid figure, which is the MPG.

While all this does mean that MPG is a standardised measurement, there’s still likely to be a discrepancy between the estimate and how many miles your car can actually do with one gallon on the road. So, keep in mind that you may have to take the MPG figure with a pinch of salt.

Converting MPG into MPL

One of the main issues with MPG is that in the UK, we now buy petrol and diesel by the litre, instead of by the gallon.

If you want to know your MPL, then take the MPG figure of your car and divide it by 4.54.

This is because there are 4.54 litres in a gallon – it’s that easy. This formula should give you a clearer sense of how far your car can actually go on a full tank of fuel.

How to improve your car’s MPG

If you’re keen to try and improve your car's fuel-efficiency, there are heaps of ways to get more out of a tank of petrol. Here are some easy ways to help both the planet and your purse:

1.  Check your tyre pressure: having the wrong tyre pressure can make a real difference to your car’s fuel-economy, but luckily this is a cheap and easy problem to fix.

Read more: How often should you check your tyres?

2.  Reduce your idling time: if you’re sitting in traffic or waiting to collect someone, turn your engine off. Leaving the engine to idle gets zero miles per gallon, and wastes billions of gallons of petrol and diesel every year.

3.  Get rid of extra weight: by ditching things like the roof box, or whatever’s hanging around in the boot (unless you really need it), you can hugely improve the fuel consumption of your car. After all, this goes down the heavier your vehicle is.  

4.  Adjust your driving style: habits like revving your engine and accelerating fast use more fuel than necessary, so you can save petrol or diesel by changing gear earlier and speeding up more gradually.

5.  Replace old/faulty spark plugs: as these are responsible for sparking the engine in your car to ignite the fuel, faulty spark plugs can really reduce fuel-efficiency. Replacing them every 20,000 miles or so should prevent this from happening.

There you have it! All the need-to-know info about MPG. If you’re keen to find out more, check out our blog about the most fuel-efficient cars on the used car market.

Previous Article

What is excess in car insurance

Next Article

Road rage brits top tips to stop getting riled up on the roads