True MPG: 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?...

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.

The 10 least fuel-efficient cars tested:

M340i Front

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.

Read our full BMW 3 Series Touring review >>


9. Audi Q7 50 TDI

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Audi Q7 60 TFSIe

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.

Volvo XC40 D4 R-Design front three quarters

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.

Read our full Volvo XC40 review >>


7. Mercedes S500

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New BMW 7 Series vs Mercedes S-Class

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.

Read our full Mercedes S-Class review >>


6. Land Rover Discovery 3.0 SDV6

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Used Land Rover Discovery 4x4 (17-present)

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.

Read our full Land Rover Discovery review >>


=4. Mercedes-AMG GLC 43

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Mercedes-AMG GLC 43 front

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.

Read our full Mercedes GLC review >>


=4. Porsche Macan Turbo Performance Pack

Buy a new Porsche Macan with What Car? >>

BMW M3 vs Porsche Macan Turbo

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.

Read our full Porsche Macan review >>


3. Mercedes S500 Cabriolet

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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.

Read our full Mercedes S-Class Cabriolet review >>


2. Audi SQ5

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Audi SQ5

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.

Read our full Audi SQ5 review >>


1. Alfa Romeo Giulia Quadrifoglio

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New Alfa Romeo Giulia Quadrifoglio vs BMW M3

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.

Read our full Alfa Romeo Giulia Quadrifoglio review >>


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