True MPG: which cars beat their official figures – and which are farthest away?

New petrol, diesel and hybrid cars are on average 8.2% less efficient in real-world conditions than the official WLTP figures suggest, What Car? has found.

We put 168 popular models through our independent True MPG test, with the worst performers 26.4% down on their official numbers, but the best almost 19% up.

WLTP is, however, a lot more accurate than the old NEDC system, which it replaced in September 2018; a previous sample of 159 vehicles type approved to NEDC standards showed an average discrepancy of 20.2% between True MPG and the official results, with the worst performers as much as 40% thirstier than advertised.

To ensure accuracy and repeatability, our True MPG tests are conducted in strictly controlled laboratory conditions, but they are based on a real route that takes in town, rural and motorway driving.

As a result, they 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.

So, which of the latest models were farthest away from their official figures, and which over-achieved? Let's take a look, starting with the 10 biggest under-performers…

Under-performers

10. BMW 3 Series 320d M Sport Pro Edition

Official WLTP average 56.5mpg True MPG 45.2mpg Difference 19.9%

Despite appearing on this list, the 3 Series is well worth considering, because it's fantastic to drive and has the most user-friendly infotainment system around. Bear in mind, though, that the 330e plug-in hybrid version makes a lot more sense than this 2.0-litre diesel model – particularly as a company car.

Read our full BMW 3 Series review

9. Toyota Camry 2.5 Hybrid

Official WLTP average 51.4mpg True MPG 41.1mpg Difference 20.0%

The latest Camry is a spacious executive saloon that comes well equipped. However, it suffers from a poorly controlled ride and the 2.5-litre petrol engine needs to be worked surprisingly hard at times. This latter issue probably contributes to the disappointing real-world fuel efficiency.

Read our full Toyota Camry review or see the latest Toyota Camry discounts

8. Citroën C3 Puretech 110 Flair Plus EAT6

Official WLTP average 51.3mpg True MPG 41.0mpg Difference 20.1%

With its funky looks, the C3 does a great job of turning heads. However, in addition to falling around 10mpg short of its official economy in the form we've tested, it's poor to drive and not very practical. As a result, any number of small car rivals are more recommendable on an objective level.

Read our full Citroën C3 review or see the latest Citroën C3 discounts

7. Ford S-Max 2.5 ST-Line

Official WLTP average 43.5mpg True MPG 34.6mpg Difference 20.4%

If you think MPVs can't be fun to drive, the S-Max will force you to reconsider, thanks to its precise steering and excellent body control. And while the interior isn't as classy as some rivals', it is practical. Just don't expect the 2.5-litre petrol version to be a particularly frugal choice. 

Read our full Ford S-Max review

6. Nissan Micra 1.0 Tekna

Official WLTP average 50.4mpg True MPG 40.1mpg Difference 20.4%

The peppy performance of Nissan's 1.0-litre petrol engine impresses, even if its True MPG figure doesn't. But perhaps the Micra's biggest problem is that it's merely okay in most respects, despite competing in a class that's packed with talent.

Read our full Nissan Micra review or see the latest Nissan Micra discounts

5. Volvo XC60 B5D Inscription Pro AWD

Official WLTP average 44.1mpg True MPG 34.6mpg Difference 21.6%

While they're about as on-trend as safari suits, diesel engines can still make plenty of sense in large SUVs such as the XC60. However, the B4D is the Volvo diesel unit we'd recommend you look at, rather than the B5D that features here.

Read our full Volvo XC60 review or see the latest Volvo XC60 discounts

4. Suzuki Swace 1.8 Hybrid SZT

Official WLTP average 64.2mpg True MPG 50.3mpg Difference 21.6%

The Swace is essentially a rebadged version of the Toyota Corolla Touring Sports, and shares that car's hybrid engine. But despite being able to run on electric power for short distances, it was still far adrift of the official government fuel economy figure. More positively, it offers a comfortable ride and lots of standard kit.

Read our full Suzuki Swace review or see the latest Suzuki Swace discounts

3. Volvo XC40 T4 R-Design Pro

Official WLTP average 34.8mpg True MPG 27.1mpg Difference 22.1%

Overall, the XC40 is the best family SUV on sale, because it blends generous passenger space and a practical boot with a quality feel and top-notch safety. The latest T4 model is even an efficient choice, unlike its predecessor, which averaged just 27.1mpg in our tests.

Read our full Volvo XC40 review or see the latest Volvo XC40 discounts

2. Renault Arkana 1.6 S Edition

Official WLTP average 58.9mpg True MPG 45.5mpg Difference 22.8%

If you’re after an affordable coupé SUV that’s still pretty practical, the Arkana is worth a look. And a True MPG figure of 45.5mpg isn't overly disappointing – until you see how far that is from the official average.

Read our full Renault Arkana review or see the latest Renault Arkana discounts

1. BMW 4 Series 420d M Sport Pro Edition

Official WLTP average 57.6mpg True MPG 42.4mpg Difference 26.4%

Our reigning Coupé of the Year might be more fun to drive than its rivals and surprisingly practical, but there's no getting around the fact that the 420d diesel version was farther away from its WLTP average than any other car we've tested. We'd therefore go for the cheaper and sweeter-sounding 420i petrol.

Read our full BMW 4 Series review or see the latest BMW 4 Series discounts

Next: Cars that beat their official fuel economy figures >>

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