Real MPG: most economical luxury cars

What Car?'s Real MPG tests show what fuel economy you can really expect from a car. Here, we reveal the best and worst-performing luxury cars and SUVs we've ever tested...

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Alasdair Rodden
Published27 April 2024

The official MPG figures published in car sales brochures can tempt you into buying a certain model, but those results can be misleading, so you may not be able to match the figures when you take the car home. To show you the sort of fuel economy you can expect in real-world use, we conduct our own Real MPG tests.

BMW X5 with Real MPG logo

We're counting down the top 10 most economical luxury cars, starting with the most economical: the 2016-2024 Mercedes E-Class. The best luxury cars are desirable, and sought after for their sumptuous interiors, high levels of comfort and supreme refinement. Buyers' expectations are high, then, and despite the obvious opulence, decent fuel economy is still an important factor.

So, here are the models which cost the least – and the most – to run.

How we test for a car's Real MPG

Our Real MPG tests are carried out on a rolling road under laboratory conditions. That means variables such as weather and traffic can’t affect our results, ensuring that they’re comparable. The routes the cars take are based on a realistic mix of roads.

Every car we test is weighed and has its tyre pressures checked, then we hook up an exhaust connection to measure the car's emissions. The car's climate control is set to 21 degC or, if it has manual air conditioning, the temperature is set to its midway point, and the fan speed to its lowest setting. We turn off the headlights and don't use other electrical equipment, such as heated seats or the stereo.

In the test, we sample each car's tailpipe emissions every second. The Real MPG scores you see in this story are calculated from an average of those results.

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


  • Sumptuous interior
  • Supple ride
  • Well equipped


  • Not as fun to drive as some rivals
  • E220d not as quiet as some diesels

NEDC MPG 72.4mpg | Real MPG Average 44.8mpg | Town 34.7mpg | Motorway 41.4mpg | Rural 59.2mpg

The previous-generation E-Class is very well equipped and available with a great range of engines, from fuel-sipping diesels and punchy petrols to a tax-efficient plug-in hybrid (PHEV).

It's the diesel-powered E220d that wins top honours in the luxury car class for frugality, though. It's not just good for fuel economy, either – it also has plenty of oomph, and is impressively quiet and comfortable on a motorway. Meanwhile, the classy interior is suitably upmarket and decently spacious.

Read our full used Mercedes E-Class review

Our pick: 530e M Sport 4dr Auto

0-62mph: 6.8 sec
MPG/range: 470.8mpg
CO2 emissions: 13g/km
Seats: 5
Boot: 520 litres
Insurance group: 39E


  • Delightful to drive
  • Well equipped
  • Very economical


  • A little pricey
  • Average rear seat space
  • Slight question mark over reliability

NEDC MPG 68.9mpg | Real MPG Average 43.5mpg | Town 34.3mpg | Motorway 39.9mpg | Rural 57.2mpg

We're big fans of this 5 Series – indeed, it's a former What Car? Car of the Year and remains a top choice on the used luxury car market. As well as offering refinement, practicality and comfort galore, it's also efficient, especially if you opt for the 2.0-litre diesel engine in this 520d model.

In our real-world tests, it returned an impressive 39.9mpg on a motorway, and up to 57.2mpg on country roads.

Read our full used BMW 5 Series review


  • Comfortable ride
  • Composed handling
  • Great refinement


  • Diesel isn't as efficient as some rivals
  • Expensive to maintain

NEDC MPG 50.4mpg | Real MPG Average 35.1mpg | Town 27.0mpg | Motorway 33.2mpg | Rural 45.2mpg

If you want refinement, comfort and even semi-sensible running costs, few cars can beat the previous-generation S-Class.

Like all of the engines in the S-Class range, the 258bhp diesel engine fitted to this model is hushed at speed, but produces enough power to make acceleration effortless in almost any scenario. It's also fairly efficient, returning 33.2mpg on a motorway in our hands, and 27.0mpg around town. The best news is that prices start from just £15,000.

Read our full used Mercedes S-Class review

Our pick: xDrive50e M Sport 5dr Auto

0-62mph: 4.8 sec
MPG/range: 313.9mpg
CO2 emissions: 20g/km
Seats: 5
Boot: 500 litres
Insurance group: 49E


  • Fantastic plug-in hybrid version
  • Great to drive
  • Classy, well-designed interior


  • Wide standard tyres generate road noise at speed
  • Third row of seats costs extra
  • There are more spacious and practical rivals

WLTP MPG 34.9mpg | Real MPG Average 34.1mpg | Town 25.1mpg | Motorway 31.7mpg | Rural 46.3mpg

The BMW X5 offers comfort, refinement and the best infotainment system around. No matter which engine you go for, you’ll be impressed, but it’s the xDrive30d that’s put the X5 on this list.

It’s a 282bhp 3.0-litre diesel engine which offers punchy performance from low down in its rev range and, thanks to a quick-shifting automatic gearbox, doesn't struggle when you've filled the car to the rafters. It managed 25.1mpg around town in our tests, and 31.7mpg on a motorway.

Read our full BMW X5 review


  • Smooth and powerful engines
  • Great ride on air suspension
  • Wonderful build quality


  • Not as sharp to drive as some rivals
  • Plug-in hybrid loses seven-seat option
  • Expensive to run

NEDC MPG 47.9mpg | Real MPG Average 34.0mpg | Town 29.7mpg | Motorway 30.7mpg | Rural 42.4mpg

The 272bhp 3.0-litre diesel engine we rank here is no longer available to order in a new Q7, but there are plenty of examples available on the used market, and prices aren't as high as you might think (search for a used Audi for sale for examples).

No matter which version you go for, you'll enjoy a smooth and powerful engine, plus superb interior quality and a boot that can swallow everything you choose to take with you – even if that includes the kitchen sink.

Read our full used Audi Q7 review

Our pick: 2.0 B5P [250] Core 5dr AWD Geartronic

0-62mph: 7.7 sec
MPG/range: 33.6mpg
CO2 emissions: 190g/km
Seats: 7
Boot: 302 litres
Insurance group: 37E


  • Classy interior
  • Seven-seat versatility
  • Well equipped


  • Ride slightly unsettled
  • Road and suspension noise
  • Reliability average

WLTP MPG 41.5mpg | Real MPG Average 33.9mpg | Town 26.6mpg | Motorway 31.1mpg | Rural 44.9mpg

This version of the XC90 luxury SUV is powered by a 2.0-litre diesel engine with mild-hybrid assistance. It works well mostly, although if you're fully loaded with people and luggage, you'll need to put your foot down to build speed quickly. It's also no longer available to buy new, so you'll have to settle for a used example.

We don’t include plug-in hybrids in our Real MPG tests, but if you want a new Volvo XC90, the T8 PHEV model should also keep fuel bills relatively low – it can officially cover up to 42 miles on electric power alone.

Read our full used Volvo XC90 review

Our pick: 3.0 D300 Dynamic SE 5dr Auto

0-62mph: 6.1 sec
MPG/range: 38.9mpg
CO2 emissions: 191g/km
Seats: 5
Boot: 647 litres
Insurance group: 48E


  • Offers lots of Range Rover qualities for a lower price
  • Incredible ability off-road
  • Fantastic range on the PHEV model


  • Cheaper than a Range Rover, but still very expensive
  • Rivals are sharper to drive
  • Land Rover’s reliability record is a concern

WLTP MPG 38.3mpg | Real MPG Average 33.5mpg | Town 23.2mpg | Motorway 32.5mpg | Rural 45.5mpg

If you want a luxury SUV that blends a supple ride with agile handling, but that can also impress when you venture off the beaten track, the Range Rover Sport is second to none.

The D350 diesel engine fitted to our test car is incredibly refined (although the petrol plug-in hybrids are smoother still), while being punchy enough to launch the Sport from 0-62mph in 5.9sec. However, we reckon the entry-level 3.0-litre D300 is the diesel to go for; it still offers strong performance, but for a much lower price.

Read our full Range Rover Sport review

Our pick: 300kW 55 Quattro 114kWh Sport 5dr Auto

0-62mph: 5.6 sec
CO2 emissions: 0g/km
Seats: 5
Boot: 569 litres
Insurance group: 49E
Buying & Owning


  • Spacious interior
  • Fantastic build quality
  • Strong range of engines


  • Pricey to buy
  • Lack of physical buttons for infotainment system
  • Iffy reliability and average warranty

WLTP MPG 33.6mpg | Real MPG Average 33.3mpg | Town 23.6mpg | Motorway 32.6mpg | Rural 43.6mpg

Not to be confused with the Audi Q8 e-tron electric SUV, this Q8 is powered by a 282bhp, 3.0-litre V6 diesel engine. As well as proving to be relatively efficient, almost matching its WLTP figure in our testing, it offers more than enough performance – although it’s let down somewhat by a hesitant automatic gearbox.

The Q8 is also a great place to be; interior build quality is on a par with that of the BMW X6, and rear head room is impressive considering the sleek coupé roofline.

Read our full Audi Q8 review

Our pick: xDrive40d MHT M Sport 5dr Step Auto

0-62mph: 5.9 sec
MPG/range: 36.2mpg
CO2 emissions: 205g/km
Seats: 7
Boot: 750 litres
Insurance group: 50E
Buying & Owning


  • Supremely quiet and comfortable
  • Incredibly spacious and practical
  • Great infotainment system


  • There are cheaper alternatives
  • Looks won’t be to all tastes
  • No plug-in hybrid or electric option

WLTP MPG 35.8mpg | Real MPG Average 31.7mpg | Town 18.4mpg | Motorway 33.6mpg | Rural 45.6mpg

The X7 is the largest and most luxurious SUV BMW makes, and impresses with its spacious and practical interior, its class-leading infotainment system, and its refinement.

The 3.0-litre diesel engine that kicks off the range has 347bhp and can hit 60mph in a swift 5.9sec – making it faster than most rivals – yet is also smooth and hushed. It returned upwards of 45mpg on country roads and 33.6mpg on a motorway, but just 18.4mpg around town.

Read our full BMW X7 review

Our pick: 450h+ 2.5 5dr E-CVT [Premium Pack]

0-62mph: 6.5 sec
MPG/range: 256.8mpg
CO2 emissions: 25g/km
Seats: 5
Boot: 612 litres
Insurance group: 44E


  • Comfortable ride
  • Very reliable
  • Hybrid frugal around town


  • No seven-seat option
  • Poor boot space
  • Fiddly infotainment

WLTP MPG 34.4mpg | Real MPG Average 30.8mpg | Town 45.2mpg | Motorway 23.7mpg | Rural 37.4mpg

The RX L has a bit of an advantage over most models on this list when it comes to town driving, because it's a hybrid car. In our urban tests, it managed 45.2mpg, but that fell to 23.7mpg on a motorway.

We like the model's long list of standard equipment and good interior build quality, but a fiddly infotainment system and the fact that some rivals are better to drive count against it.

Read our full used Lexus RX review

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And the least economical luxury cars...

Mercedes S-Class S500

NEDC MPG: 40.9mpg | Real MPG Average: 26.9mpg | Town: 18.3mpg | Motorway: 27.4mpg | Rural: 34.6mpg. The S500 promises a cosseting ride, superb refinement and, er, substantial fuel bills. That said, it fell short of the RX by less than 4mpg in our tests. Read our review

Land Rover Discovery 3.0 TD6

NEDC MPG: 39.2mpg | Real MPG Average: 26.3mpg | Town: 20.3mpg | Motorway: 25.3mpg | Rural: 32.6mpg. The Discovery may be able to take you further than many luxury cars, but it’ll cost you – it’s even thirstier than the luxurious Range Rover Sport. Read our review

Audi S8

WLTP MPG: 24.6mpg | Real MPG Average: 21.7mpg | Town: 13.5mpg | Motorway: 23.8mpg | Rural: 27.6mpg. The S8 gets a 563bhp 4.0-litre petrol engine capable of launching you to 62mph in just 3.8sec, and has incredible refinement and a plush interior. Just be sure y... Read our review