True MPG: The most efficient cars revealed

What Car?'s True MPG tests show what fuel economy you can really expect from a car. So, what are the best performing models we've ever tested?...

True MPG - Mercedes GLE emissions test

Filling up with fuel is an expensive business right now, so if you're thinking of changing your car, there's a good chance that getting something more efficient is a high priority.

The trouble is the official government fuel economy figures you'll see printed in sales brochures are often misleading, proving impossible to match in real-world conditions.

That's why we carry out our own True MPG tests, which show what's achievable if you’re driving gently and sticking to speed limits, but aren’t resorting to any unrealistically slow acceleration or special 'hypermiling' techniques.

Here we're taking a look at the 10 most efficient cars we've ever tested. And then we'll reveal the 10 least efficient.

1. The most fuel-efficient car - Toyota Yaris Cross 1.5 Hybrid

Toyota Yaris Cross front right tracking

True MPG 60.1mpg

Take the ultra-efficient 1.5-litre petrol engine and electric motor from the Toyota Yaris, then stick it in a car with chunkier styling, and the result is the Yaris Cross. To many people, its small SUV styling will instantly make it more desirable. And, thanks to a bigger battery, it can actually go farther on electric power than its hatchback sibling.

Indeed, the Yaris Cross is the most efficient car we've ever tested, not only averaging more than 60mpg, but managing a staggering 103.3mpg in the urban part of our test.

Read our full Toyota Yaris Cross review or see our latest Toyota Yaris Cross deals

How we test for a car's True MPG

Our True MPG tests take place in laboratory conditions on a rolling road to ensure that variables such as weather and traffic do not affect the results. This guarantees that our tests are repeatable. However, the cycle is based on a real-world route.

To ensure accuracy, we weigh every test car and check its tyres are correctly inflated before we begin. We then fit an exhaust connection to measure emissions.

The car's climate control is set to 21 degrees, or the midway point if it has manual air conditioning, with the fan speed set to its lowest setting. Additionally, we switch off all electrical equipment, including the headlights, heated seats, and stereo.

During the test, we monitor the car's tailpipe emissions every second. The True MPG results displayed in this story are based on the average reading.

Find out more about how we test for True MPG >> 

The rest of the top 10

2. Toyota Yaris 1.5 Hybrid

Toyota Yaris 2021 front

True MPG  59.93mpg

Hybrid cars don't come any cheaper than the latest Yaris, yet it's also exceptionally frugal, only being beaten by its Yaris Cross sister. Add in perky performance, and it's easy to recommend, despite the fact there are plenty of rivals that offer more space for rear passengers and luggage.

Read our full Toyota Yaris review or see our latest Toyota Yaris deals

3. Suzuki Ignis K12D 1.2 Dualjet Hybrid

Suzuki Ignis 2021 front cornering

True MPG 59.9mpg

This version of the Ignis SUV is a mild hybrid, which means a small electric motor works alongside its 1.2-litre petrol engine to help get you moving and reduce the strain on the engine. It's front-wheel drive, but even if you decide four-wheel drive is a must, the average True MPG only drops to 53.3mpg.

Read our full Suzuki Ignis review or see our latest Suzuki Ignis deals

4. Skoda Octavia 2.0 TDI 115

Skoda Octavia Estate 2021 front cornering

True MPG 57.9mpg

If you cover enough annual miles to justify having a diesel engine, then this 2.0-litre unit in the Skoda Octavia will save you a bundle on running costs. The Octavia is a seriously impressive family car in other respects, too, with a spacious and practical interior and a plush ride. True, this engine is no longer available, but there are plenty of examples on the used market.

Read our full Skoda Octavia review or see our latest Skoda Octavia deals

5. Suzuki Celerio 1.0

2018 Suzuki Celerio 1.0 SZ4 auto

True MPG 57.8mpg

Despite being one of the cheapest new cars around until it was taken off sale in 2019, the Celerio came with a decent array of equipment, including air conditioning, a DAB radio and Bluetooth connectivity. The only engine option was a pretty lively and extremely frugal 1.0-litre.

Read our full used Suzuki Celerio buying guide or see our latest used Suzuki Celerio deals

6. Vauxhall Astra 1.6 CDTi 110 Ecoflex

How to buy your perfect Vauxhall Astra

True MPG 56.3mpg

For a long time, we didn't rate the Astra particularly highly, but this was the generation that changed that. It had a lightweight construction, which helped efficiency, plus it was spacious and well priced.

Read our full used Vauxhall Astra review or see our latest used Vauxhall Astra deals

=7. Honda Jazz 1.5 i-MMD Hybrid

Honda Jazz 2022 front right tracking

True MPG 56.0mpg

The Jazz's party piece is its practical interior, which includes cinema-style flip-up rear seats, which allow you to create a second boot when you don't have rear passengers. Unlike the Ignis – but like the Yaris Cross and Yaris – it's a full hybrid that's capable of running purely on electric power for short distances.

Read our full Honda Jazz review or see our latest Honda Jazz deals

=7. Seat Leon 1.6 TDI 110 Ecomotive

2019 Seat Leon front

True MPG 56.0mpg

The Leon is Seat's answer to the Ford Focus and Vauxhall Astra, and in addition to good real-world fuel economy, this previous-generation version offers tidy handling and a long list of standard equipment. Just make sure you can live with its rather firm ride.

Read our full used Seat Leon buying guide or see our latest used Seat Leon deals

=7. Volkswagen Up 1.0 S/S 60

Volkswagen Up

True MPG 56.0mpg

It's been around for a while, but the Up remains a solid choice if you're in the market for a small car, thanks to its smart interior and fun handling. This 1.0-litre petrol engine may only have 59bhp, but that means it has enough pep for city streets. You'll quickly feel out-matched on the motorway, though.

Read our full Volkswagen Up  review or see our latest Volkswagen Up deals

10.  Suzuki Baleno 1.0

2016 Suzuki Baleno 1.0 Boosterjet review

True MPG 55.2mpg

Sold between 2016 and 2019, the Baleno is a small yet practical hatchback that will also cost you a pittance to buy and run. You'd never describe it as fun to drive, but the ride is generally comfortable.

Read our full used Suzuki Baleno buying guide or see our latest used Suzuki Baleno deals

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Read more: The 10 least efficient cars >>

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