True MPG: most and least efficient cars revealed

What Car?'s laboratory tests use a real-world driving route to show what fuel economy you can really expect. So, what are the best and worst performing cars?...

What Car?’s True MPG real-world fuel economy figures show what sort of efficiency you can really expect from your car.

Suzuki Ignis - True MPG logo

Tests are conducted in a laboratory to ensure repeatability within 1%, but they are based on a real-world route that takes in town, rural and motorway driving.

The results reflect 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.

True MPG is not only fully reflective of real-world performance; it is also much more realistic than the official government fuel economy figures that car manufacturers have to quote.

The True MPG tests are carried out under tightly controlled conditions: climate control is always set to 21deg and cars due to be tested are stored overnight at a set 23deg so they all start with exactly the same engine temperature and in the same ambient air temperature.

In this slideshow, we reveal the 10 most efficient cars we've tested so far – and the 10 that used the most fuel.

The 10 most fuel-efficient cars tested

Seat Ibiza

10. Seat Ibiza 1.0 TSI 95

True MPG 54.0mpg

The 1.0 TSI 95 Ibiza is a former What Car? Small Car of the Year, thanks to its sharp handling, remarkably spacious interior and strong yet efficient petrol engine. And while it's since been surpassed by the Volkswagen Polo, it remains a fine choice.

9. Skoda Superb Estate 2.0 TDI 150

Skoda Superb Estate 2019 front right cornering

True MPG 54.8mpg

Proof that it's not only small cars that are efficient comes from the Skoda Superb Estate. It's one of the biggest and most practical estates you can buy, yet still returned almost 55mpg in our test.

=6. Renault Kadjar 1.5 dCi 110

Renault Kadjar front

True MPG 55.2mpg

Renault's Kadjar SUV is closely related to the hugely popular Nissan Qashqai, but it’s a slightly more fuel efficient choice, being capable of more than 55mpg in real-world driving if you go for the 1.5-litre diesel engine.

=6. Skoda Citigo 1.0 60

Skoda Citigo

True MPG 55.2mpg

These days the Citigo is offered only as a fully electric car, but if you're buying used it's often cheaper to run than its siblings – the VW Up and the Seat Mii – despite being just as good to drive. Just bear in mind that this engine feels rather underpowered once you're outside the city limits.

= 6. Suzuki Baleno 1.0

Suzuki Baleno 1.0 Boosterjet SZ-T

True MPG 55.2mpg

Level with the Kadjar and Citigo in terms of its True MPG result is the Suzuki Baleno. A small yet practical hatchback, it was discontinued in 2019.

5. Volkswagen Up 1.0 75

Volkswagen Up 2020 RHD front tracking

True MPG 55.9mpg

It's been around for a while, but the Up remains one of the best city cars on sale, thanks to its smart interior and fun handling. This 74bhp 1.0-litre petrol model is the most efficient, but even the punchier 89bhp turbo version returned almost 54mpg in our True MPG test.

4. 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, offers tidy handling and a long list of standard equipment. Just make sure you can live with its rather firm ride.

3. Vauxhall Astra 1.6 CDTi 110 Ecoflex

Vauxhall Astra cornering front three quarters

True MPG 56.3mpg

In the past, we haven't rated the Vauxhall Astra particularly highly, but in its latest form the car is much more impressive. It has a lightweight construction which aids efficiency, plus, it's spacious and well priced.

2. 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.

1. Suzuki Ignis SHVS

Suzuki Ignis 2019 front

True MPG 59.6mpg

The SHVS version of the Ignis SUV, which is front rather than four-wheel drive, is the most efficient car we've ever tested. It's a mild hybrid, which means a small electric motor works alongside its 1.2-litre petrol engine, helping to get you moving and reducing the strain on the engine. Even if you decide four-wheel drive is a must, the average True MPG only drops to 53.3.

Now let's take a look at the least efficient cars we've tested...

The 10 least fuel-efficient cars tested

Porsche Macan - True MPG logo

So, you've seen the most efficient cars, all of which average more than 53mpg in real-world driving conditions, but which cars use the most fuel?

Here we answer that question and see just what they do deliver if you’re driving gently and sticking to speed limits, but aren’t resorting to any unrealistically slow acceleration or special 'hypermiling' techniques.

10. BMW 3 Series M340i Touring

m340i

True MPG 28.0mpg

If you’re after a practical estate that offers effortless performance, and class-leading handling and composure regardless of conditions, look no further. If you're after efficiency, on the other hand, look elsewhere.

9. Audi Q7 50 TDI

audi-q7-2020-cornering

True MPG 27.2mpg

Add up all of the stars in our 16-point road test, and the Q7 has a higher score than any other car on sale today. The only significant chink in its armour – at least when it comes to this 50 TDI version – is fuel economy.

8. Volvo XC40 T4

Volvo XC40 2020 RHD front tracking

True MPG 27.1mpg

We've big fans of this family SUV in diesel form: it was even our 2018 Car of the Year. However, while this turbocharged 2.0-litre petrol version is nice to drive, a True MPG of 27.1 makes it significantly harder to recommend.

7. Mercedes S500

Mercedes S-Class S350d L AMG Line

True MPG 26.9mpg

The S-Class has long been one of the best luxury saloon around and is extremely relaxing to drive or be driven in. However, despite featuring mild hybrid technology, the S500 version is anything but frugal.

6. Land Rover Discovery 3.0 SDV6

Land Rover Discovery front three quarters

True MPG 26.3mpg

Large, luxurious SUVs aren't an efficient breed, but even by the standards of the class the Land Rover Discovery gulps down a lot of fuel, barely topping 26mpg.

=4. Mercedes-AMG GLC 43

Mercedes-Benz GLC 43 AMG

True MPG 25.3mpg

If you get your thrills from blasting away from traffic lights and listening to a piercing V6 soundtrack, the GLC 43 is well worth a look. It’s even practical and easy to drive when you’re in family mode. But it's never what you'd call frugal.

=4. Porsche Macan Turbo Performance Pack

Porsche Macan S front

True MPG 25.3mpg

The Macan Turbo is a rival for the GLC 43, and averaged the same 25.3mpg when we put it through our True MPG test. However, it's since been given a new engine and is the more rewarding car to drive.

3. Mercedes S500 Cabriolet

Mercedes S-Class Cabriolet

True MPG 25.2mpg

As with the Macan, this version of the S-Class Cabriolet has now been superseded, but the car itself remains on sale and is the best luxury drop-top you can buy.

2. Audi SQ5

Used test: Audi SQ5 vs Mercedes-AMG GLC 43

True MPG 24.6mpg

Like the rival GLC 43 and Macan Turbo, the SQ5 is as heavy on fuel as it is light on its feet – or at least it was until Audi swapped the petrol engine for a diesel. Strengths also include a beautifully built interior.

1. Alfa Romeo Giulia Quadrifoglio

Alfa Romeo Giulia Quadrifoglio 2019 front tracking

True MPG 23.5mpg

Like so many cars in this bottom 10, the Giulia Quadrifoglio is designed for performance rather than efficiency. Indeed, it's our reigning Performance Car of the Year, which tells you just how good it is at the things it specialises in.

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