Running a car certainly isn’t cheap. You’ll fork out almost £438,000 over a lifetime of driving, with annual fuel costs of around £1,435, according to a 2022 study by car finance lender CarMoney .

Keeping fuel costs to a minimum is a smart money-saving move. So what’s the difference in price when running a petrol or diesel car?

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Something as simple as changing where you park can save fuel. Instead of finding the most convenient spot, try parking somewhere that you can easily pull out of facing forward. This avoids the need for reversing manoeuvres, which are less fuel efficient.


1. Anything above 50mpg is regarded as good fuel economy

2. At 75mph a car uses around 18% more fuel than at 60mph

3. Driving 220 miles in a petrol or diesel car will cost around £41 in fuel

What is good fuel economy?

As a general rule of thumb, cars with good fuel economy will do more than 60mpg. So, if you’re in the market for a new car, finding one with high mpg is a good way to save on day-to-day running costs.

Anything over 50mpg is considered decent fuel consumption, but if you’re getting less than 25mpg, your car’s fuel economy is poor.

Petrol or diesel car: which is more fuel efficient?

Generally, diesel engines have a better fuel economy than petrol engines. When consumer champions Which? tested diesel, petrol and hybrid cars, they found that diesel cars were more efficient by an average of about 5 miles per gallon (mpg). However, the most fuel efficient cars are fully hybrid, achieving almost 7mpg more than the average diesel vehicle.

Even though diesel costs more when you fill up at the pump, it’s likely to save you money overall. That said, there will be significant variances between different car models, so it’s a good idea to do plenty of research on fuel economy before you buy a vehicle, whether petrol or diesel.

Average fuel economy: petrol vs diesel vs hybrid

Here’s a comparison of the average fuel economy of petrol, diesel and petrol-hybrid (not plug-in) cars, looking at fuel economy both around town and out on the motorway and country A roads.

Fuel type

Average mpg (combined)

Average mpg (around town)

Average mpg (out of town)

Average mpg (motorway)
















*Source: Which?

How TO improve fuel economy when driving

You can get the maximum mileage from your petrol or diesel tank by following these simple fuel-saving tricks:

Make your vehicle lighter

A very simple way to improve your vehicle’s fuel economy is to reduce its weight. Take out any items from the boot that you don’t actually need, and remove things like roof boxes or bike racks if they aren’t being used. Not only do they add to the weight of the car, but they also increase the wind resistance the vehicle faces, increasing the strain.

The fuel you put in your vehicle is also heavy, so avoid filling your tank right to the brim at the garage as this will add more unnecessary weight to your car.

Turn off the air conditioning

Let’s be honest, in the UK we often don’t have much need for air conditioning. What’s more, putting it on will cause you to use much more fuel. So, unless it’s absolutely sweltering and simply opening the window won’t do the job, then leave it turned off.

Watch your speed

Breaking the speed limit is not only a surefire way of having an accident or getting in trouble with the police, it’s also a massive waste of fuel.

Fuel consumption increases dramatically at high speeds, according to the Energy Saving Trust . For instance, at 75mph a car uses around 18% more fuel than at 60mph. For a van it’s around 37% more.

Change gears smoothly

If you accelerate, brake and change gears smoothly, you’ll use less fuel and therefore boost your fuel economy. It’s a good idea to move up a gear as early as you can. Under normal conditions, you should change the gears when the revs are between 1,500rpm and 2,000rpm .

Avoid stop-start driving

Every time you have to stop and start, you use more fuel. So keep an eye on the road ahead of you. If you’re coming into some traffic, ease off the accelerator well in advance. The traffic may have started to clear by the time you reach it, saving you from having to brake harshly and then start up again.

Switch off your engine when stationary

You shouldn’t leave your engine running when you stop as this wastes fuel. Many modern cars have stop-start technology that automatically cuts the engine off when the vehicle is stationary. But if you don’t have this feature, it’s worth switching off your engine if you’re stopping for longer than a minute or two.

Carry out regular maintenance

Keeping your car in tip-top condition ensures it runs as efficiently as possible. Remember to get your car serviced once a year as this protects its longevity. Although this can be expensive, it can save you a lot of money in the long run.

Cut the cost of your fuel

No matter whether you’re using a petrol or diesel motor, a simple way to improve your fuel efficiency is to pay less for your fuel.

There are plenty of smart ways you can do this, including making use of petrol station loyalty schemes and shopping around for cheaper fuel. You can do this using sites like – just enter your postcode and it will tell you the prices currently being charged at your local forecourts.

Of course, you could buy an electric car. According to figures from the Energy Saving Trust , a full charge in a pure electric vehicle will give a typical range of 220 miles and cost £23 if charging at home. Driving the same distance in a petrol or diesel car will cost around £41 in fuel.

Original article written 7th October 2020, updated 21st January 2024

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