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:

2014 Jaguar F-type Coupe R review

True MPG 28.8mpg

One of the best things about the Jaguar F-Type is its V6 engine, because this makes a fantastic noise. However, it also likes a drink, returning just 28.8mpg in our True MPG test.

Read our full Jaguar F-Type review >>

9. Cupra Ateca

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Cupra Ateca

True MPG 28.5mpg

As the first model from Seat’s freshly spun-off performance brand, the Cupra Ateca needed to be special. And sure enough it combines scintillating performance with impressive practicality while undercutting all its sports SUV rivals. Just don't expect it to be cheap to run.

New Alpine A110 vs Audi TT RS vs Porsche Cayman

True MPG 28.4mpg

The latest version of Porsche's Cayman sports car swaps the flat-six engine of old for a four-cylinder unit in order to meet the emissions and fuel consumption targets demanded of it, but it's not enough to stop it appearing on this list. Fortunately, the Cayman can fall back on the fact it's one of the best handling cars on sale.

Read our full Porsche 718 Cayman 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

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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

A 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 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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