Real MPG: The most efficient cars revealed

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

Real 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 Real 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. 

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

Toyota Yaris Cross front right tracking

Real MPG Average 60.1mpg | Town 103.3mpg | Motorway 45.5mpg | Rural 70.5mpg

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.

For Very efficient | Lofty driving position | Uncluttered dashboard

Against Could be more spacious | Vocal engine when accelerating | Not as fun to drive as some rivals

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

Read on to find out how we find your car's Real MPG, and see more of the cars which performed well in our tests.

How we test for a car's Real MPG

Our Real 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 Real MPG results displayed in this story are based on the average reading.

Read more: How we test a car's Real MPG

The rest of the top 10

2. Toyota Yaris 1.5 Hybrid

Toyota Yaris front right driving

Real MPG Average 59.93mpg | Town 80.0mpg | Motorway 46.7mpg | Rural 74.1mpg

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.

For Excellent real-world fuel economy | Toyota's reliability record | Slow predicted depreciation

Against Below-par infotainment system | Firm ride on high-end models | Cramped in the back

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

3. Suzuki Ignis K12D 1.2 Dualjet Hybrid

Suzuki Ignis front right driving

Real MPG Average 59.9mpg | Town 51.3mpg | Motorway 53.3mpg | Rural 74.8mpg

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 Real MPG only drops to 53.3mpg.

For Good fuel economy | Spacious for a small car | Generous equipment

Against Ride can be fidgety | Vague steering | Poor infotainment system

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

Real MPG Average 57.9mpg | Town 50.5mpg | Motorway 52.1mpg | Rural 72.6mpg

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.

For Plush interior | Huge boot | Low BiK rates for the plug-in hybrid version

Against Heating controls on the touchscren | Rivals are sharper to drive

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

Real MPG Average 57.8mpg | Town 47.0mpg | Motorway 53.3mpg | Rural 73.5mpg

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.

For Cheap to run | Spacious by class standards | Reliability record

Against Cheap-feeling interior | Limited infotainment options

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

Real MPG Average 56.3mpg | Town 46.4mpg | Motorway 50.7mpg | Rural 73.7mpg

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.

For Spacious interior | Relatively cheap to buy | Well equipped

Against Vague steering | Diesels can be noisy | Low-speed ride can be fidgety

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 front static

Real MPG Average 56.0mpg | Town 68.8mpg | Motorway 43.4mpg | Rural 73.0mpg

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.

For Great seating flexibility | Lots of standard equipment | Slow depreciation

Against Pricey by small car standards | Not the quietest cruiser | Disappointing infotainment system

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

Real MPG Average 56.0mpg | Town 46.3mpg | Motorway 50.9mpg | Rural 71.7mpg

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.

For Good to drive | Well equipped | Cheap to buy and run

Against Firm ride | Not as refined as some rivals | Bland interior

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 front cornering

Real MPG Average 56.0mpg | Town 44.3mpg | Motorway 51.9mpg | Rural 72.2mpg

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. The Up has just been axed from Volkswagen's new car line-up, but there are plenty of examples available on the used market – and some versions can still be ordered from stock.

For Good fun to drive | Economical engines | Relatively classy interior

Against Limited safety technology | Some rivals offer better value | Harsh ride on larger wheels

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

Real MPG Average 55.2mpg | Town 46.6mpg | Motorway 49.9mpg | Rural 70.4mpg

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.

For Comfy ride | Spacious interior and boot | Affordable ownership costs

Against Vague steering | Interior feels flimsy in places | Unrefined and noisy at speed

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

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