One of the most important factors to consider when buying a new car is how fuel-efficient it is, especially if you drive a lot of miles per year. In this article, we’ll run through some of the most fuel-efficient cars on sale today. 

How is Fuel Efficiency Measured? 

Miles per gallon is the standard measure of fuel efficiency in the UK, although the European Litres per 100km standard is sometimes quoted by German, French and Italian car manufacturers.  

How do you work out fuel efficiency? 

Many modern cars have an MPG readout on the digital dashboard, but if you want to double-check your MPG, or calculate it yourself, it’s quite simple: 

When you fill-up your tank, reset your car's trip computer.  

1. Drive until you need to fill up again, alternatively, you can monitor it over a long journey, as long as you fill up again at the end.  
2. When you fill-up again, make a note of the amount of fuel dispensed. 
3. With your data collected, first convert the number of litres used into gallons by dividing by 4.54. 
4. Then divide the number of miles by the number of gallons.  

This gives you the MPG figure for that tank of fuel/journey. 

What are the most fuel-efficient cars in the UK?

With most car manufacturers focussing their research and development on improving fuel efficiency, there are plenty of cars to choose from if you want a high MPG figure: Here’s our top list of fuel-efficient cars in the UK. 

7. Mercedes C-Class C300 e - 470 MPG

Since its introduction, the C class has been a top contender in the luxury saloon market, but with the latest hybrid powertrain, it is also one of the best options for fuel efficiency.  

Achieving over 470 MPG in Mercedes’ tests, it far surpasses the next best petrol or diesel hybrid cars. The large hybrid battery pack contributes significantly to this enormous MPG figure, meaning it can drive quite a distance before even needing to call upon the 2.0L petrol engine. 

6. Skoda Octavia iV - 256.8 MPG 

If you need more boot space and don't want an SUV, the Skoda Octavia iV could be the perfect option. It boasts over 250 miles per gallon from its 2.0-litre petrol engine and hybrid motor combination but affords over 500L of boot space. Making it a very functional and efficient family car. 

As with other Skodas, the interior and trim is purposeful and well-made. Whilst the tech has improved massively over the last 5-10 years, they’re still slightly behind the competition of Mercedes and BMW in finish level and luxury.  

5. BMW 330e - 217 MPG 

The BMW 3 series is another saloon car favourite, boasting impressive handling and road-holding capabilities alongside the comfort and luxury required of a German cruiser.  

Alongside the 2.0-litre turbo petrol engine, the 330e has a large battery and motor combination pushing the total horsepower to nearly 300 bhp. The 330e slightly outpaces the C300 e to 60mph, too. 

4. Peugeot 308 Hybrid 180 - 210 MPG 

If you don't need the height and bulk of an SUV or the luggage space of an Estate, the Peugeot 308 Hatchback might fit the bill nicely. It has just enough room to carry 5 adults and a reasonably sized boot.

The 1.6-litre petrol engine and motor propel the car to 60 in around 7 seconds, meaning it has a reasonable turn of pace.  

It can also do nearly 40 miles on electric power alone, meaning if your commute to work is short, you might never need to fill up at the petrol station between weekends! 

3. Lexus NX Hybrid - 84 MPG

As the first SUV in our lineup of fuel-efficient cars, the Lexus NX is a great choice for efficiency, luxury and SUV styling. Packed with incredible safety features including the latest dynamic radar cruise control for collision avoidance.  

At 84 MPG it does not fare as well as the saloons and estates it competes with, but it still does well, considering its nearly 2 tonne kerb weight. 

2. Toyota Prius - 67.3 MPG 

The car that popularised the hybrid technology still remains one of the most commonly seen petrol/electric vehicles on the road. Considering the Toyota has incredible reliability scores, great MPG and clever packaging, it's not too surprising.  

Favoured by Uber drivers the world over, the Prius offers plenty of space for 5 adults and their luggage and is not likely to break the bank on fuel costs or repairs.  

The 2023 model achieves just over 67 MPG, it’s important to note that this is the first self-charging hybrid listed, plug-in hybrid MPG figures are often higher than self-charging ones, as they include the energy put into the battery via home charging, whereas self-charging hybrids need no additional energy other than filling up with petrol. 

1. Hyundai Tucson PHEV - 80 MPG 

If you’re looking for a more affordable Hybrid SUV, the Tucson is a great choice, with over 80 MPG achievable, and more than 550 litres of luggage space in the rear, it’s perfect for the cost-conscious large family.  

Like many other PHEVs discussed, the Tucson can do nearly 40 miles on electric-only power, with the 1.6-litre turbocharged engine kicking in to help out when required. 

Hyundai has really begun to target the high-end sector with their recent models, with premium features like smart parking assist, radar cruise control and top-spec infotainment systems.  

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Author - Joseph Law

Joseph has been writing about cars for over seven years and writing for Bumper for over two, blending his passion for automobiles with a talent for storytelling.

Joseph has written about engineering and cars for Autozilla, Komaspec, and several engineering manufacturers. When he's not writing or tinkering with one of his five cars, Joseph dreams of owning an Alfa Romeo 33 Stradale.