Real MPG: the least economical new cars you can buy

What Car?'s Real MPG tests show what fuel economy you can really expect from a car. Here are the least efficient models you can currently buy in the UK...

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by
Darren Moss
Published16 June 2024

The official WLTP fuel economy tests you'll find printed in manufacturers' sales brochures don't always accurately reflect what you can expect your new car to achieve in the real world. To provide you with a more realistic figure, we devised our unique Real MPG test, which simulates real-world town, motorway and rural driving routes.

Silver Audi S8 driving with Real MPG logo

Below, we've listed the 10 models currently on sale which performed worst in our testing. If minimising running costs is high on your list of criteria for your next car, these models are best avoided – our rundown of the most economical cars you can buy will help steer you in the right direction.

That's not to say that we'd never recommend any of the models which appear on this list, though. Indeed, the Audi S8 that tops this list is the least economical car we've ever tested, yet its blend of huge power and sublime comfort makes it a great high-end luxury car.


How we test for a car's Real MPG

Although our tests are carried out in a laboratory (to ensure that the results are repeatable), the simulation used is based on a real-world driving route that takes into account a realistic variety of road conditions. Our Real MPG scores reflect what’s achievable if you drive carefully, but without resorting to extreme 'hypermiling' techniques.

Each car is weighed, and has its tyre pressures set to match the manufacturer's recommendations. The climate control is set to 21 degC – or the midway point if the car has manual air conditioning – and the headlights and stereo are switched off.

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

Our pick: S8 Quattro Vorsprung 4dr Tiptronic

0-62mph: 3.8 sec
MPG/range: 24.6mpg
CO2 emissions: 261g/km
Seats: 5
Boot: 505 litres
Insurance group: 50E
Driving
Interior
Practicality
Buying & Owning

Strengths

  • Savage straight-line pace
  • Comfortable and incredibly refined
  • Plush interior

Weaknesses

  • Not the most agile performance car
  • Muted engine note won’t appeal to all
  • Fiddly infotainment system

WLTP MPG 24.6mpg | Real MPG Average 21.7mpg | Town 13.5mpg | Motorway 23.8mpg | Rural 27.6mpg

If you're lucky enough to own this range-topping version of the Audi A8, you’re probably not overly worried about running costs. That being said, we suspect that real-world economy figures like these would be enough to make even CEOs wince. Indeed, if you do most of your journeys around town, the S8 could cost you seven times as much in fuel  as the most economical car we've ever tested.

Aside from its thirst, the 563bhp 4.0-litre V8 petrol engine is hugely impressive. Not only does it emit a cultured roar when you put your foot down, but it’s also incredibly powerful. This heavy, 5.2-metre-long limo can slingshot from 0-62mph in a mere 3.8sec and feels effortlessly fast at higher speeds (such as on a derestricted autobahn).

With four-wheel steering and prodigious grip, the S8 feels more agile through corners than you might expect, although the steering isn’t the most communicative. And despite its sporting nature, the S8 still has a smooth ride that befits a luxury car.

The S8 keeps the feeling of luxury going inside, with every surface being covered in top-notch materials and every switch and dial moving with slick precision. Occupants are exceptionally well isolated from wind and road noise at higher speeds, too. And even though the S8 isn’t available in long-wheelbase form like the A8, there’s still plenty of room for your passengers, as well as all of their luggage in the boot.

Read our full Audi S8 review

Driving
Interior
Practicality
Buying & Owning

Strengths

  • Big cargo bay with a high payload capacity
  • Space for four six-footers in Double Cab versions
  • Good to drive for a pick-up

Weaknesses

  • Not the cheapest pick-up
  • Warranty could be better

WLTP MPG 20.5mpg | Real MPG Average 24.0mpg | Town 16.0mpg | Motorway 24.1mpg | Rural 32.2mpg

While the Ford Ranger Raptor’s place on this list will have you thinking that its fuel economy is a disaster, there’s some good news here, because its average real-world economy is actually 17.1% better than the official figure would have you believe.

The Raptor is designed to mix sports SUV performance with the practicality of the regular Ford Ranger pick-up truck, and key to its appeal is its 288bhp 3.0-litre V6 petrol engine. While the level of performance isn’t transformative next to the cheaper, slightly more efficient 2.0-litre diesel Raptor, it still feels quick considering its sheer size.

When you venture off road, you’ll find the Raptor to be virtually unstoppable, with its chunky off-road tyres and hardcore 4x4 mechanicals keeping you moving when the Tarmac has long since run out. Just bear in mind that the Raptor isn’t quite as practical as the regular Ranger, with a smaller payload (652kg) and a lower towing limit (2500kg).

Read our full Ford Ranger review

Driving
Interior
Practicality
Buying & Owning

Strengths

  • Cheap by all-wheel-drive sports SUV standards
  • Just as practical as a regular Seat Ateca
  • Very well equipped with a user-friendly dash

Weaknesses

  • Interior starting to look dated
  • So-so interior quality
  • Engine could sound fruitier

WLTP MPG 31.4mpg | Real MPG Average 28.5mpg | Town 23.1mpg | Motorway 26.9mpg | Rural 35.0mpg

This is the range-topping version of Cupra’s sports SUV, which itself is based on the Seat Ateca family SUV. Now, you wouldn’t expect a high-performance SUV with close to 300bhp, four-wheel drive and a 0-62mph time of 4.9sec to be as frugal as a regular petrol or diesel equivalent, but this Ateca is seriously thirsty. At least it’s slightly cheaper to buy than a Volkswagen T-Roc R and is predicted to hold on to its value better than many other sports SUVs.

Choosing this engine gets you lower, stiffer suspension that improves body control through corners, but all versions handle well. It’s just a shame the engine doesn’t sound great unless you specify the optional (and expensive) Akrapovič sports exhaust system.

Despite its sporty brief, the Ateca still works well as practical family transport. And while it doesn’t match the BMW X2 for interior quality, it feels functional and built to last, plus it’s generously equipped.

Read our full Cupra Ateca review

Driving
Interior
Practicality
Buying & Owning

Strengths

  • Surprisingly smart interior
  • Refined engine
  • Great towing ability

Weaknesses

  • Bouncy, uncontrolled ride
  • Rivals have bigger load bays
  • Shortage of modern safety kit

WLTP MPG 31.7mpg | Real MPG Average 29.0mpg | Town 20.5mpg | Motorway 28.7mpg | Rural 37.2mpg

Korean car maker Ssangyong recently changed its name to KGM, but the Musso nameplate remains for the brand’s pick-up truck. The Musso is a hardy workhorse, being able to tow up to 3500kg even when you’ve filled its load bay – something no rival can manage.

Stick with the lower trim levels and the Musso represents startlingly good value next to rivals such as the Ford Ranger and Volkswagen Amarok. It’s worth upgrading your Musso to Saracen trim if you can, though, because that brings luxuries such as cruise control, leather seats and heating for both the front and rear seats. Occupants of any of those seats will find that head and leg room are generous, as is storage space.

Given the hard life that most pick-up trucks have to endure, we doubt anyone would expect stellar fuel economy, but most diesel rivals can beat the Musso’s 29.0mpg average. The Amarok, for example, returned 36.7mpg in our hands, while the Isuzu D-Max managed 35.2mpg.

Read our full KGM Musso review

Reliability
Safety
Costs
Quality
Performance

Strengths

  • Big boot
  • Impressive interior space
  • Relatively agile for a family SUV

Weaknesses

  • Interior quality not up to usual Audi standards
  • Firmer ride than some rivals
  • Fiddly infotainment system

WLTP MPG 31.7mpg | Real MPG Average 29.5mpg | Town 23.0mpg | Motorway 28.4mpg | Rural 36.3mpg

If you buy the fastest and most powerful petrol-powered version of the Audi Q3, you’re probably more interested in its performance than its fuel economy. And that’s just as well, because while its 242bhp turbocharged 2.0-litre petrol engine can propel it from 0-62mph in just 5.8sec, you’ll pay the price at the fuel pumps, especially if you spend much time driving in town or on the motorway.

Economy aside, there’s lots to like about the Q3. Cars on standard suspension (rather than the stiffer set-up of S line and Black Edition models) provide a comfy ride – although the Range Rover Evoque and Volvo XC40 are plusher still – while the Q3 is more agile through corners than most other family SUVs.

Although interior quality isn’t quite up there with the class best, the Q3 is spacious and practical inside, with sliding rear seats that allow you to prioritise boot space (which is already plentiful) or rear leg room.

Read our full Audi Q3 review

Our pick: 1.0 EcoBoost Hybrid mHEV Titanium 5dr

0-62mph: 10.2 sec
MPG/range: 54.3mpg
CO2 emissions: 118g/km
Seats: 5
Insurance group: 15E
Driving
Interior
Practicality
Buying & Owning

Strengths

  • Well equipped
  • Great driving position
  • Even more fun with the grippy Track Pack

Weaknesses

  • Infotainment system can be fiddly to use
  • Interior is a bit low rent
  • Steering is inconsistently weighted

WLTP MPG 35.3mpg | Real MPG Average 29.6mpg | Town 21.2mpg | Motorway 29.5mpg | Rural 37.2mpg

Ford has a huge legacy in the world of hot hatches, and although the Ford Focus ST will cost you more than most rivals to run, it remains a strong option for drivers seeking affordable fun, thanks to competitive pricing.

Key to the fun is its 2.3-litre petrol engine. A 276bhp power output is enough to propel the ST from 0-62mph in a brisk 5.7sec. That’s on a par with the rival Hyundai i30 N and Volkswagen Golf GTI, but the Honda Civic Type R is faster still.

We like the Focus ST’s agile handling, and although you’ll feel bumps and potholes more than you would in the standard Ford Focus due to its stiffer suspension, the ride isn’t uncomfortable by the standards of the class.

The ST is the same as any other Focus when it comes to space, and that’s a good thing, because it means your rear passengers will have more room to stretch out in than they would in most rivals. The boot is large, too, although the Cupra Leon’s can hold a little more.

Read our full Ford Focus ST review

Our pick: 420i M Sport 2dr Step Auto

0-62mph: 8.2 sec
MPG/range: 41.5mpg
CO2 emissions: 154g/km
Seats: 4
Boot: 385 litres
Insurance group: 32E
Driving
Interior
Practicality
Buying & Owning

Strengths

  • Range-topping M440i is seriously rapid
  • More fun to drive than direct rivals
  • More room in the back than you might imagine

Weaknesses

  • Some wind and tyre noise
  • Back seats don't split and fold down
  • Divisive looks

WLTP MPG 34.4mpg | Real MPG Average 29.6mpg | Town 20.2mpg | Motorway 29.6mpg | Rural 38.7mpg

On the right road, with the roof down and the sound of a 369bhp six-cylinder petrol engine ringing in your ears, you might not care all that much about running costs. The trouble is, once that joyful drive is over, reality sinks back in, and the reality of this range-topping BMW 4 Series Convertible model is that it’ll cost you a lot at the pumps.

Not that we’d blame you for choosing one anyway, of course. After all, the M440i takes just 4.9sec to sprint from 0-62mph, accompanied by a soulful soundtrack. And if you put the automatic gearbox into its sport mode, it’ll make slick changes to make the most of that power.

Despite carrying some extra weight, the drop-top handles almost as sharply as its coupé sibling, yet with optional adaptive suspension fitted, its ride can be softened off to make it a comfy cruiser. It’s surprisingly practical, too, with seating for four adults and a decent-sized boot, while its interior is high in quality and more user-friendly than most.

Read our full BMW 4 Series Convertible review

Driving
Interior
Practicality
Buying & Owning

Strengths

  • Smooth and punchy engines
  • High-quality interior
  • Tidy handling and good ride in the right spec

Weaknesses

  • Potentially firm ride on S line Sport suspension
  • Not as practical as cheaper Q5
  • Fiddly touchscreen infotainment system

WLTP MPG 32.1mpg | Real MPG Average 29.8mpg | Town 22.3mpg | Motorway 28.5mpg | Rural 38.3mpg

The Audi Q5 Sportback is the sleeker sibling of the Audi Q5 SUV, and it’s available with either petrol or diesel power. The 45 TFSI’s 2.0-litre petrol engine we tested here pulls well, with its 261bhp helping it to outsprint the diesel alternative to 62mph, but you won’t want to keep your foot planted for long, as our fuel economy figures show.

As with the regular Q5, the Sportback’s classy interior features plush materials and a robust feel. It pips the rival BMW X4 for quality, although its reliance on a touchscreen or voice control means its infotainment system isn’t as user-friendly as that of the X4 (which has a physical rotary controller between the front seats).

Despite its sloping rear roofline, the Q5 Sportback is better than the X4 and Mercedes-Benz GLC Coupé for rear passenger space, and its boot is still sizeable and a usefully square shape, so it’s far from impractical.

Read our full Audi Q5 Sportback review

Our pick: 2.0 TDI Life 5dr DSG

0-62mph: 11.6 sec
MPG/range: 43.5mpg
CO2 emissions: 170g/km
Seats: 7
Boot: 469 litres
Insurance group: 26E
Driving
Interior
Practicality
Buying & Owning

Strengths

  • Exceptionally good predicted residual values
  • Good value against van-based MPV rivals
  • Lots of safety tech

Weaknesses

  • Infotainment not the best
  • No rear air-con as standard

WLTP MPG 31.4mpg | Real MPG Average 30.4mpg | Town 21.6mpg | Motorway 29.8mpg | Rural 39.6mpg

With 201bhp, this 2.0-litre petrol version of the Volkswagen Multivan offers punchy performance, even with all seven seats occupied. However, most Multivan buyers will prefer the 2.0-litre diesel option for its lowdown pulling power and superior fuel economy. Indeed, the 2.0 TSI’s thirst on anything other than rural roads won’t be to anyone’s liking.

At least the Multivan is a practical choice, with space for everyone to stretch out, and room for a couple of overnight bags in the boot even with all the seats in place. Remove the back row and the Multivan does a passable impression of, well, a van.

Up front, you’ll find a comfortable driving position and supportive seats, and while there are lots of hard plastics on display, at least they look and feel more inviting than those of the rival Toyota Proace Verso.

The Multivan is pricier than most rival MPVs, but it should hold on to its value exceptionally well, offsetting those higher running costs.

Read our full Volkswagen Multivan review

Our pick: 2.2 D 210 Sprint 5dr AWD Auto

0-62mph: 6.6 sec
MPG/range: 46.3mpg
CO2 emissions: 160g/km
Seats: 5
Boot: 525 litres
Insurance group: 34D
Reliability
Safety
Costs
Quality
Performance

Strengths

  • Good to drive
  • Rotary controller for infotainment
  • Responsive automatic gearbox

Weaknesses

  • Rear space not as generous as rivals
  • Fidgety low-speed ride
  • Noisy diesel engines

WLTP MPG 33.2mpg | Real MPG Average 30.9mpg | Town 23.0mpg | Motorway 29.5mpg | Rural 40.0mpg

If you spend a lot of time meandering along country roads, you might wonder why the petrol-powered version of the Alfa Romeo Stelvio SUV is here, because it’s capable of up to 40mpg. Around town and on the motorway, however, its economy plummets to the point where you’re likely to spend a big portion of your time filling up the fuel tank.

You might also be tempted to sacrifice some of that rural efficiency when you discover how much fun the Stelvio is to drive. With 276bhp and a 0-62mph time of 5.7sec, it feels faster than its size suggests. It also flows through corners with greater agility than most other family SUVs, helped by remarkably direct steering and superb body control. The downside is a rather firm ride, meaning you’ll feel more lumps and bumps than you would in rivals such as the Audi Q5 and BMW X3.

Those cars beat the Stelvio for interior quality and space, too, with rear head room restricted by the Stelvio’s sloping roofline. Its boot is a good size, though, so the Stelvio is still practical enough for family duties.

Read our full Alfa Romeo Stelvio review