Economy drive: how to save fuel

How to save fuel

Yesterday, we took part in the WLTP Challenge: a driving event designed to show cars can meet – or exceed – the new standardised WLTP fuel economy figures. The aim: to save fuel.

Our car for the 250-mile challenge was an Alfa Romeo Giulia Quadrifoglio, a performance car capable of achieving 27.2mpg if your willpower is strong enough to resist unleashing the full fury of its Ferrari-derived 2.9-litre twin-turbocharged engine.

You can find out if we exceeded the WLTP figure in a future update.

We shared the drive with a representative from the RAC, who was on hand to share some fuel saving tips as we made our way from Bristol to Birmingham and then back again via the Cotswolds. When you’re hypermiling a 510hp Alfa Romeo, every little helps.

Here are eight ways to save fuel, courtesy of the RAC.

Look after your vehicle

Regular maintenance of your vehicle will ensure that it’s working at optimum efficiency, which will improve your fuel economy. Stick to the manufacturer’s recommended service schedule, which includes regular oil and filter changes, and be sure to fix any issues as they arise.

You also need to ensure that the tyres are inflated to the correct pressures, so consult the car’s handbook or use one of the many online guides for help. Remember to adjust the tyre pressures depending on the load you’re carrying.

Go easy on the throttle

Alfa Romeo Giulia Eco rating

If our WLTP Challenge experience taught us anything, it’s that feathering the throttle can make a huge difference to your fuel consumption. Slow and gentle acceleration is the key to efficient driving, so avoid any traffic light Grand Prix antics.

Change up a gear as soon as possible, but don’t allow the engine to labour. Experience will tell you when your car is ready for a higher gear – there’s no fixed rule.

While 56mph is often referenced as the optimum speed for fuel economy, the RAC says cars are typically most efficient at 45-50mph.

Maintain momentum

Momentum is the difference between good and excellent fuel economy. During the WLTP Challenge, we found that roundabouts, roadworks, hills and the actions of other drivers can take a serious chunk out of efficiency.

The key is to read the road ahead. If you’re approaching a roundabout, ease off the throttle and see if you can tackle it without stopping. Equally, on a motorway, maintaining a safe distance to the car in front will allow you to react to sudden braking.

Hills are the hypermiler’s worst enemy. Watching the Alfa Romeo’s economy gauge drop to zero was frustrating and almost unavoidable. The RAC says you should accelerate a little before approaching a hill, then ease off as you drive up. Just make sure you’re not creating congestion behind you.

Use cruise control at the right time

Proving real-world fuel economy

Cruise control will only improve fuel economy on a flat surface, so is best reserved for motorways. On the WLTP Challenge, we found that cruise control is slower to react to gradient changes, which means you miss out on some valuable throttle lift-off opportunities.

Motorways offer the best opportunity to maximise fuel economy. On the M5 stretch of the WLTP Challenge, the Alfa Romeo was showing a claimed 44mpg on the digital display. By the time we had completed a mixture of urban and rural roads, we had lost around 10mpg.

Reduce drag

According to the Energy Saving Trust, an empty roof rack adds 16 percent drag when driving at 75mph, while a road box adds 39 percent. Neither of these were fitted to the Giulia, but make sure you remove them from your car when you’ve returned home from holiday.

Opening a window will have a similar effect, especially at higher speeds. In town, at lower speeds, an open window will be more efficient than using air conditioning.

Turn off the air conditioning

Alfa Romeo WLTP Challenge

Speaking of which… The air conditioning uses engine power and therefore increases fuel consumption. If you’re hoping to maximise fuel economy, use it sparingly and when necessary, but be realistic.

Make sure that you use the air conditioning at least once a month, as this keeps the refrigerant flowing and the system lubricated. Failure to do so will result in an expensive repair bill further down the line.

During the WLTP Challenge, we managed to avoid using air conditioning for the majority of the trip, but the system was forced into action when the heavens opened and the windows started to mist up. Saving fuel is one thing, but safety comes first.

Avoid short trips

An engine will operate at its most efficient when it’s warm, so cold starts will increase fuel consumption. Is it possible to combine several short trips into one? Could you cycle, walk or use public transport instead?

Reduce weight

WLTP Challenge sealed

The heavier your vehicle, the more fuel it will use, which is why many manufacturers have removed spare wheels from their cars.

Remove unnecessary items from the boot, as this will improve your economy. You could also use it as an excuse to leave your mother-in-law at home.

Click here to find out what the WLTP car fuel economy test means for you, and be sure to check back for our report on the WLTP Challenge 2019.

How to slice your monthly fuel costs

How to slice your monthly fuel cost

Where do you fill up?

The cost of fuel varies greatly depending on where you buy and who you’re buying from. Paying 123p per litre of petrol instead of 129p equates to 30p per gallon. 

If your car manages 40mpg and you do 800 miles a month, that’s £6 back in your pocket just by being picky about where you buy fuel.

We have an extensive guide and regularly updated guide to finding fuel at the right price.

How do you drive?

How to slice your monthly fuel cost

How you drive is the main factor in much fuel you use. Here’s how changing your behaviour can save you money.

  • Speed

The easiest way to stop burning so much fuel is to slow down. A few miles per hour here and there can make a difference. Speed limits save your wallet as well as your licence.

Figures from the Department for Transport suggest that driving at a steady 50mph instead of 70mph can improve fuel economy by as much as 25 percent. You’ll use around 10 percent more fuel at 80mph than you will at 70mph, too. 

  • Engine revs

Don’t over-rev, either. Generally speaking, you’ll be able to feel in the rev range where your engine is most comfortable. 

The Department for Transport recommends changing up a gear before the rev counter reaches 2,000rpm in a diesel car and 2,500rpm in a petrol. Read the road ahead to ensure you’re not in too high a gear for hills and roundabouts.

Stay safe driving in Europe

  • Smoothness and preparation

By accelerating and decelerating in a smooth and relaxed manner, you can expect to save around 20 percent in fuel. Figures suggest that non-aggressive driving and anticipating the road ahead could see this rise to as much as 30 percent.

Anticipate where stops are coming and let off the throttle to coast down. Last-minute hard braking is a serious waste of energy, unless you’re driving a hybrid. Even then, there are precious yards of distance you were still using fuel where you could have been coasting. 

Keep acceleration smooth, too. How close your right foot is to the floor directly relates to how much fuel is being pumped into the engine.

How to slice your monthly petrol and diesel costs

  •  Fuel-burning features

Turning off air conditioning will improve your fuel economy, but opening windows on the motorway could decrease it. As a guide, keep windows shut at speeds in excess of 60mph. In general, air conditioning will have the greatest impact on your economy at lower speeds, especially during city driving.

Remember, air conditioning can also help de-mist a car, so using it is preferable to leaving the car idling while you wait for windows to clear.

  • Plan your journey

When you drive and which route you take can have as much of an effect on fuel consumption as how you drive. Avoid busy periods, plan shorter or less congested routes. Not only is driving on a clear road a joy, it’s also nice and efficient.

Apps like Waze and Google Maps can help with establishing the best route. And while we’re talking about planning, let’s circle back to ‘Where do you fill up?’ quickly. Whatever you do, don’t fill up at a motorway services. All this is for nothing if you wind up paying 10p a litre over the odds. Start with a cheap full tank and know where your fuel stops will be.

Do you look after your car?

How to slice your monthly fuel cost

Look after your car and it’ll look after your wallet, both in terms of maintenance and fuel costs.

  • Servicing

An engine is only efficient if looked-after. Sticking to service intervals and making sure your fluids are at the correct levels is essential for getting the best performance and economy. A well-maintained car will also last longer.

Consult your handbook to find out when your car is next due a service.

  • Tyres

The tyres are the only bit of the car that touches the road, so they’re important to keep an eye on. Too little tread is dangerous, while too little air is dangerous and expensive.

Research by Continental suggests that tyres account for 20 percent of a car’s total fuel consumption, so it pays to take care of your rubber. Reduce rolling resistance by 10 percent and you can expect a 1.6 percent drop in fuel consumption. 

Make sure you’re car is tracking straight, too, as incorrect alignment can cause unnecessary drag and wear on the tyres.11

How to slice your monthly fuel cost

  • Unnecessary weight

The more your car has to carry, the harder it has to work, which in turn leads to reduced fuel efficiency. While forcing the kids to get a gym membership might be a bit excessive, it’s worth ridding your boot of excess luggage.

The RAC says that, on average, every 50kg you carry will increase your fuel consumption by two percent. That’s based on the percentage of extra weight relative to the vehicle’s weight, so the smaller the car, the greater the effect.

  • Remove the roof rack

Anything that reduces your car’s aerodynamic performance will have a negative impact on fuel consumption. More figures from the RAC suggest that even an empty roof rack can increase fuel consumption by 10 percent.

Add the additional weight of a fully-loaded roof rack and the net result could seriously hamper your chances of saving money. If it’s not being used – remove it. And that includes the roof bars, too.

This is how Peugeot Citroen calculates real-world fuel economy

This is how Peugeot Citroen calculates real-world fuel economy

This is how Peugeot Citroen calculates real-world fuel economy

PSA Peugeot Citroen has revealed the exact methods it uses to calculate real-world fuel economy figures across its range.

The company announced real-world figures for 30 cars across its range earlier in the year, and has said it plans to reveal 20 more by the end of the year.

It’s part of a move to appear more transparent, with PSA being one of a number of manufacturers blaming the official NEDC fuel economy test for generating unachievable MPG figures.

Why is the official NEDC test to blame for unachievable fuel economy figures?

The New European Driving Cycle (NEDC) fuel economy test is used to calculate official MPG and CO2 figures for all new cars on sale in Europe.

The test is split into two sections: urban and extra-urban cycles. The first test, the urban cycle, covers a stop/start journey of 2.5 miles at an average speed of 12mph, intended to be representative of driving through a congested town or city. The car starts off cold and touches a maximum top speed of 31mph.

After this test, the now warmed-up car is put through the extra-urban cycle. This covers a distance of 4.3 miles at an average speed of 39mph.

This is how Peugeot Citroen calculates real-world fuel economy

The CO2 and fuel economy results for each cycle are then combined to provide the official CO2 and fuel economy figures quoted by manufacturers.

However, the official test has been criticised by consumers and car manufacturers alike. Carried out on a rolling road, it’s not influenced by real-life conditions such as other traffic, weather conditions and driving styles.

Developed before hybrid and electric vehicles were commonplace, it also produces extremely unrealistic fuel economy and CO2 figures for cars such as the Mitsubishi Outlander PHEV. As the test takes place when the plug-in hybrid Outlander is freshly charged, it covers most of it under electric power, hence the Outlander’s official 156.9mpg. When the Outlander’s short electric-only range runs out, its real-life fuel economy will be much lower than this figure.

So what’s Peugeot Citroen doing about it?

PSA Peugeot Citroen has announced that, along with the official NEDC tests (a European requirement), it will conduct real-world fuel economy tests across its range, and publish its findings.

To carry out the tests, the car manufacturer is working with environmental organisation Transport & Environment. It tests cars in real-world conditions, stipulating that ambient temperatures must be ‘normal’ (not too hot or too cold), while a set route should be followed.

During the test, 22.8km (14.2 miles and 24.7% of the total distance) must take place in urban areas; 39.6km (24.6 miles and 42.9% of the total distance) on rural roads; and 29.9km (18.6 miles and 32.4% of the total distance) on motorways.

This is how Peugeot Citroen calculates real-world fuel economy

Tyres must be inflated to ‘normal’ pressures and the driver should ideally not be a trained driver. The car should be driven exactly as a customer would, with all speed limits adhered to and typical acceleration for the type of car.

The test also requires at least one passenger being carried in the car, with the climate control being set to 21°C.

Transport & Environment’s clean vehicles director, Greg Archer, said: “The real-world test developed with PSA Group provides full transparency towards customers and more representative information to drivers than the new laboratory test, helping them choose the most fuel-efficient cars. This scientific approach is robust, reproducible and reliable in measuring real carbon emissions.

“We urge the European Commission and all carmakers to use this test for regulatory and advertising purposes,” he added.

What are the results of PSA’s real world tests?

So far, 30 Peugeot Citroen models have completed the test, with most averaging around 20mpg below the official NEDC figure. Here’s an example of models tested, with another 20 set to be announced before the end of 2016.

CarReal MPGNEDC MPGDifference
Peugeot 108 1.2 PureTech 8246.3065.6919.39
Peugeot 308 1.6 BlueHDi 12057.6588.2830.63
Peugeot 508 2.0 BlueHDi 18044.8470.6225.78
Citroen C3 Picasso BlueHDi 10049.5674.3424.78
Citroen C4 Cactus PureTech 11046.3165.6919.38
DS4 PureTech 11052.3174.3422.03

Hot air: the worst cars for real-world CO2 emissions

PorscheSince the Volkswagen emissions scandal, the spotlight has been focused on the real world emissions of cars, rather than those produced in a lab. As Volkswagen proved, you can post exceptional results under test conditions, only for the reality to be very different indeed.

One organisation is taking a lead. Vehicle testing firm Emissions Analytics is checking the tailpipe emissions of every new car on sale, under its EQUA initiative. It’s already published data for NOx and carbon monoxide: now, it has released the findings of its latest tests for CO2 emissions – which shows car brands overall are missing their target by a whopping 39%. And some are worse still…

The British company’s number-crunching has created two figures: an indication the actual real-world CO2 for all cars on sale, plus a ‘variance factor’ that reveals by how much the real world varies from the official figure. Call this an ‘honesty rating’: 1 is most honest, 5 is least honest.

All new cars are sold with a quoted CO2 figure, which is used to calculate road tax and company car tax. But as Emissions Analytics shows, the cars of certain brands are performing far worse in reality than the figure suggest…

The car manufacturers with the highest real-world CO2

Emissions Analytics

First, to the car brands that produce the most CO2 in the real world, as opposed to a sterile and fully-controlled test bench. These makes of car are, simply put, the very biggest emitters of CO2. They’re the global warming anti-heroes.

10: Audi – 191g/km


Surprisingly, for all its TDI diesel engines and e-tron plug-in hybrids, it’s Audi that has the 10th highest real-world CO2 figure. Blame all those big Q5s and Q7s, plus the R8 supercar? Well, yes, but also blame an EQUA variance factor ‘honesty rating’ of 2.7 over what its official NEDC figures state and how the cars perform in real life. Remember, 1 is most honest and 5 is least honest.

9: Jeep – 200g/km


Jeep is an SUV manufacturer. It makes big, thirsty 4x4s. So it’s perhaps no surprise to see it appear in the CO2 emissions bad books. It’s not all bad news though: when Jeep says it’s bad in official figures, the real-world figures at least prove it’s being honest – its variance factor is just 1.1, compared to Audi’s 2.7.

8: SsangYong – 206g/km


Nearly all of SsangYong’s cars are big, too: the smallest car it makes is the Nissan Qashqai-rivalling Tivoli. Jeep’s are generally bigger though, and both its overall CO2 figure and the real-world variance over claims are better than SsangYong’s…

7: Jaguar – 207g/km


Jaguar’s cars are sporty and premium. The XE has yet to have a big impact on the range, so its overall brand CO2 is driven up by the XF, the F-Type, the XJ. CO2 emissions that vary by 2.5 times over official figures aren’t so clever either, though.

6: Lexus – 211g/km


Jaguar produces less CO2 than Lexus? Hang on a minute, surely that’s not right – Lexus is the brand of the hybrid, after all? Well, yes, but it’s also a brand that sells a lot of RX SUVs. A lower variance factor of 1.9 isn’t enough to offset that – oh, and the fact it doesn’t sell CO2-cutting diesels, either.

5: Infiniti – 213g/km


This is a poor result for Infiniti. According to Emissions Analytics, its quoted CO2 figures underplay the real-world CO2 of its cars by an ‘honesty factor’ of 3.6. The everyday CO2 of its cars is a stonking 213g/km, meaning it puts out more carbon dioxide as a brand than 4×4 specialist Jeep. We thought this brand was meant to be the smart-thinker’s alternative?

4: Subaru – 214g/km


Subaru’s turbo boxer engines sound good in the real world, but you’re best listening to them from a safe distance: their actual CO2 emissions are much higher than the claimed figures.

3: Land Rover – 223g/km

Land Rover

Like Jeep, Land Rover only makes SUVs. Big, posh, heavy SUVs, like the Range Rover and Discovery. The Evoque has helped bring down its range-average CO2 figures, but a variance factor of 2.6 pushes it back up again: bronze medal in the list of manufacturers with the highest real-world CO2.

2: Porsche – 240g/km


Porsche’s sports cars are naturally rather thirsty, and so naturally put out a lot of CO2. Even the slowest, cheapest 911 does 0-62mph in 4.6 seconds – you don’t get such performance without using a bit more fuel than average. Its range CO2 figures are pushed up further in the real world due to a variance factor of 2.0 over what it claims, too.

1: Aston Martin – 314g/km

Aston Martin

It’s perhaps no surprise to find a supercar manufacturer tops the list of the brands with the highest real-world CO2. Aston Martin’s cars all have V8s and V12s, after all. What’s positive for the brand is that its variance factor is a mere 1.0 – it says it’s bad, but it’s very honest when it says this, too.

And now it’s onto the brands whose CO2 figures mysteriously show the biggest variance in the real world compared to what they can achieve in the lab – this is precisely what let Volkswagen down…

The car manufacturers with the biggest real-world variance to official CO2 figures


Car manufacturers blame the flawed NEDC test. Campaign groups say there’s something fishy going on. Experts say brands have simply learnt how to best perfect cars to do well in the very-limited-scope official emissions test, without resorting to cheating.

Whatever the reason, there’s no denying the real-world results are often very different to what’s officially claimed in the legislated CO2 figures. And here are the worst offenders – the brands with the worst ‘honesty ratings’.

Chrysler – 3.1 times variance factor


American brand Chrysler benefits from being part of Fiat, which includes sharing Fiat engines. Which, according to Emissions Analytics, aren’t quite as green in real life as the test figures claim. Another reason for the brand being withdrawn from the UK?

Peugeot – 3.1 times variance factor


Peugeot’s real-world CO2 figures also vary over claimed statistics by a hefty factor of 3.1. And this, from a brand that’s committed to releasing real-world economy statistics for its cars. How long before customers force it to cut down this yawning variance?

Renault – 3.1 times variance factor


Renault’s HQ was raided by investigators looking into evidence of emissions test skulduggery. We’ve heard nothing since so clearly there’s nothing to report – but news of a real-world variance factor of 3.1 over claimed figures should still provide food for thought.

Volvo – 3.2 times variance factor


Volvo prides itself on being a safe, upstanding brand, and part of this sensible-shoes image is serving up great MPG and low CO2 figures. This image takes a bit of a dent, though, as Emissions Analytics finds an honesty rating of 3.2 over what it says and what real-world figures say.

Fiat – 3.4 times variance factor


Fiat’s range is dominated by small cars such as the 500 and Panda, models that will be bought to use mainly in city centres and to save fuel. Pity, then, the honesty rating of 3.4 suggests the real-world CO2 is not very likely to come close to what the official figures say…

Ford – 3.4 times variance factor


This is a significant result, because Ford is Britain’s best-selling car brand. According to Emissions Analytics, its CO2 figures have a variance factor ‘honesty rating’ of 3.4 compared to the official claimed NEDC figures, indicating that in the real world, its cars are not very likely to get close to the official stats.

Infiniti – 3.6 times variance factor


Remember, Infiniti emits one of the highest amounts of CO2: a variance factor of 3.6 suggests it’s less honest in the real world than the figures say it is. It’s not an enviable position for the premium challenger to be.

Alfa Romeo – 3.6 times variance factor

Alfa Romeo

Alfa joins Infiniti on the third-place spot in the honesty rating league table. The firm has to date sold just two cars, the Giulietta and the Mito: will the arrival of the fancy new Giulia help improve matters for the sporty Italian brand? It’s also significant in being the third Fiat Auto brand in the bottom 10…

DS – 4.7 times variance factor


The second-worst car brand for real-world CO2 diverging from the official figures is posh Citroen sister company DS. As Citroen itself isn’t among the bottom 10 (indeed, the C3 diesel is the only car to achieve the best-possible A1 rating), we’re not quite sure why this is so – perhaps the diesel-hybrid DS 5 is having an effect? Whatever the cause, it’s worth bearing in mind if you’re buying a DS with low CO2 in mind.

Smart – 5.0 times variance factor


The least honest brand for real-world CO2 figures? Surprisingly, it’s Smart – makers of the urban-hero Fortwo city car. Smart’s real-world CO2 is the furthest from the official rating of any manufacturer on sale, by the maximum-possible variance factor ‘honesty rating’ of 5.0, which means its real-world fuel economy is likely to be least like the glowing official stats as well. You may think you’re doing your bit for global warming by choosing a Smart, but the planet in reality might not thank you.


Now Suzuki HQ is raided by fuel economy investigators

SuzukiSuzuki has become the latest Japanese car maker to be raided by officials investigating apparent falsification of fuel economy tests.

The Friday raid, reports Reuters, was seeking evidence that Suzuki produced fuel economy figures from indoor tests on individual car parts, rather than the full vehicle costing tests they were meant to conduct.

Suzuki has admitted it carried out fuel economy tests ‘using an improper method’: back in May, it originally said 16 Japanese domestic market cars were affected, later upping this to 26 cars. More than 2.1 million JDM models are involved – and some of them are cars Suzuki makes for other car makers.

The brand, an expert in small and fuel-efficient models, blames a lack of resources following the 2008 global financial crisis, something reinforced by added pressure to roll out ever-more fuel-efficient cars.

There was no intention to misrepresent and inflate fuel economy figures, it insists. The Friday raid on its headquarters is part of the Japanese transport authority’s investigation into whether this is true.

Earlier in May, Mitsubishi was rocked by its own fuel economy testing scandal, where it subsequently emerged the firm has been misrepresenting mpg for the past quarter-century. A plunge in its market value subsequently saw Nissan pounce and take it over.

As is likely with Suzuki though, Mitsubishi’s British importer has confirmed no UK cars are affected and official mpg figures are correct.

Mitsubishi at London Fashion Week 2016

Mitsubishi tells UK owners, your fuel economy IS correct

Mitsubishi at London Fashion Week 2016Mitsubishi Motors UK has written to all of its British owners to confirm they are not affected by the 25-year fuel economy test rigging scandal that has engulfed its Japanese operations.

The letter follows an earlier statement mailed to owners warning them that there was a fuel consumption issue with Japanese-market cars – but that there was no evidence UK cars were affected.

Nissan to buy controlling stake in Mitsubishi

“I’m now pleased to be able to confirm for certain, following a detailed independent investigation, that no vehicles produced for UK and Europe are affected,” said Mitsubishi UK MD Lance Bradley.

Bradley states to customers that coverage around the fuel economy issue has not been entirely accurate: “The facts are that the company discovered that it had been submitting data from driving tests used in the USA to measure fuel economy, rather than driving tests required in Japan.”

Mitsubishi HQ has now confirmed cars sold in the UK and Europe are unaffected by the Japanese-market wrongdoings.

Bradley also echoed criticism from motoring experts that mainstream news outlets are confusing the Mitsubishi fuel economy rigging scandal with the Volkswagen emissions cheating scandal.

“This is not the same as the ‘emissions’ issue that has been revealed at Volkswagen.

“The testing data that has been wrongly presented relates to fuel consumption performance, not emissions into the environment.”

Nissan IDS Concept

Nissan confirms talks to buy into Mitsubishi

Nissan IDS ConceptNissan has confirmed it is in “advanced talks” with Mitsubishi to buy a stake in the firm, with sources suggesting Nissan is looking to buy a controlling stake in the crisis-hit car maker.

UPDATE: Nissan has now confirmed it is buying a 34% stake in Mitsubishi Motors for $2.2 billion (£1.5 billion). Nissan chief Carlos Ghosn vowed in a press conference to help restore trust in Mitsubishi.

Mitsubishi fuel economy test scandal: Q&A

Mitsubishi fuel economy tests ‘incorrect since 1991’

Mitsubishi reveals fuel economy test misconduct

Nissan is significantly larger that Mitsubishi, which admitted in April it has been overstating fuel economy through rigging official fuel economy tests. Mitsubishi’s stock has plummeted by more than 40% since news of the fuel economy test scandal broke, wiping £2 billion off its value.

Ironically it was Nissan that discovered Mitsubishi was overstating fuel economy, when it assessed joint venture minicars built by Mitsubishi for the two companies.

Mitsubishi has since discovered it’s been overstating Japanese market fuel economy for 25 years.

“Nissan and Mitsubishi are discussing various matters including capital co-operation, but nothing has been decided,” said the two companies in earlier statements.

Mitsubishi cars

Mitsubishi fuel economy test scandal – Q&A

Mitsubishi carsMitsubishi has admitted cheating fuel economy tests dating back to 1991 and the Japanese car company has now set up an independent investigation committee to establish just what’s been going on.

Since the news broke that 625,000 Kei cars had been given falsified fuel economy figures, Mitsubishi has lost around half the market value. It seems more bad news is likely to emerge in coming days too as attention focuses on the sixth-largest Japanese car company’s fuel economy test procedures.

Here’s what we know so far about the Mitsubishi fuel economy test cheat crisis.

What has Mitsubishi done?

Mitsubishi has overstated fuel economy figures of four cars sold on the Japanese market: the Mitsubishi eK Wagon and eK Space, and the Nissan Dayz and Dayz Roox.

Not only has testing not been conducted correctly, it was also done in a way different to that required by Japanese law – something that has infuriated Japanese ministers who have said such manipulation is “extremely serious”.

How did Mitsubishi cheat the test?

It seems misconduct centred around the running resistance value test cars were subjected to. This rolling road resistance mimics two things – the rolling resistance, largely from the tyres, and the effect of air resistance when vehicles are moving: cars are tested stationary in labs where there’s no wind resistance, so it has to artificially be applied.

An analyst put it more bluntly: Mitsubishi appears to have over-inflated the tyres to cut rolling resistance and thus artificially inflate fuel economy.

What effect would this have had on official figures?

Experts say this practice may have artificially inflated Mitsubishi fuel economy figures by around 5-10%.

Are the cars with dodgy fuel economy figures still on sale?

No – when news of the scandal broke, Mitsubishi immediately stopped production and sales of the eK models. Nissan has also stopped selling the Dayz models (and is now in discussions with Mitsubishi over compensation).

Who discovered the fuel economy test cheat?

Ironically, it was Nissan that discovered the fuel economy test misconduct, during initial development for the successor to these cars. It took evidence of the deviations to Mitsubishi, which discovered things were amiss.

Is anything else amiss with Mitsubishi’s fuel economy test procedures?

Separate to this misconduct, further revelations about how Mitsubishi carries out fuel economy testing in Japan have emerged.

Japanese fuel economy test regulations are configured differently to tests in other parts of the world to better reflect the stop-start city-style driving commonplace in Japanese driving. Remarkably, when they changed, Mitsubishi admits it did not follow this rule change.

So how long has Mitsubishi been doing this?

Alarmingly then, Mitsubishi has admitted it’s been testing fuel economy this way for a quarter of a century. “For the domestic market, we have been using that method since 1991,” said Mitsubishi vice-president Ryugo Nakao at a press conference. The regulations changed: Mitsubishi testing did not change to reflect it.

Are other Mitsubishis affected?

Mitsubishi says it’s thus likely other Japanese market cars are affected: “During our internal investigation, we have found the testing method which was different from the one required by Japanese law has been applied to other models manufactured by Mitsubishi for the Japanese domestic market.”



Does it involve emissions cheating like the Volkswagen scandal?

This is an issue related to fuel economy test figures, not emissions. While any official emissions figures may well be different once fuel economy is restated, this will be an incremental addition – unlike Volkswagen, Mitsubishi has not been employing ‘cheat’ devices that alter the engine to get back emissions regulations.

Thus far, the Mitsubishi scandal is also related to petrol cars, not diesels – and petrol cars generally meet emissions regulations with ease.


So if Japanese cars are affected, do UK Mitsubishis have dodgy fuel economy figures?

Mitsubishi says this issue is restricted to the Japanese market: there is no evidence cars sold in Europe and the U.S. are affected.

European cars are tested according to the NEDC fuel economy test cycle, which itself is largely agreed to be outdated – but it is an independent test that all cars sold in Europe must pass. Manufacturers cannot overstate fuel economy: when they do, as Volkswagen discovered last year, clarifications must be issued when it is discovered.

What is Mitsubishi doing about it?

Mitsubishi, after expressing “its most sincere apologies to all of our customers, shareholders, and stakeholders,” has set up a special investigation committee that’s fully independent from the company itself.

It will have three members – all attorneys of law – who will fully investigate the matter, see if there’s any other improper conduct at play within Mitsubishi, and then reveal both the cause and suggested remedial action to prevent it happening again.

They’ll report back in three months’ time.

Mitsubishi logo

Mitsubishi fuel economy tests have been incorrect since 1991 – report

Mitsubishi logoMitsubishi fuel economy test procedures have not been compliant with Japanese regulations since 1991, an unnamed source has revealed.

Reuters says the leaked news was first reported to Japanese business title Nikkei: Mitsubishi is to hold a press conference briefing on the matter later today.

It is said the firm compiled its fuel economy data using U.S. standards, which involves more high-speed driving, rather than Japanese standards which demand more stop-start inner-city driving. Japanese standards generally deliver worse economy figures than U.S. standards.

The latest Mitsubishi revelation follows last week’s admission that it overstated the fuel economy of four city cars, sold under both the Mitsubishi and Nissan brands.

Since then, the firm – Japan’s sixth-largest vehicle manufacturer – has lost half its market value.

Manipulation of fuel-efficiency tests is “extremely serious,” Japanese transport minister Keiichi Ishii told reporters yesterday after a cabinet meeting, reports Bloomberg.

More news as we get it

Opel Vauxhall Astra

Europe’s car makers concede: ‘We know the fuel economy test is obsolete’

Opel Vauxhall AstraEuropean car manufacturers have responded to recent tests by the British and German transport authorities by saying they know the test cycle is outdated – and for them, the new, more real-world test can’t come soon enough.

Representing Europe’s 15 vehicle makers, The European Automobile Manufacturers’ Association said it’s actually “been advocating for many years an updated laboratory test… as well as an additional new test to measure pollutant emissions on the road”, according to ACEA secretary general Erik Jonnaert.

Both are coming. A new, more representative fuel economy test called WLTP – World Harmonized Light Test Cycle and Procedures – is due to take force next year, replacing the current outdated NEDC test.

The second real-world test, called Real Driving Emissions (RDE), is due to arrive then too, although the European Commission is taking a step-by-step approach in approving it – and two key packages to help car makers start preparing for RDE are still missing and “urgently needed to complete the legislation”.

As it stands, the EC aims to present the third package in October 2016 and the fourth, final package by early 2017. Car makers, it seems, want confirmation to come sooner: the legislation is due to go live for all newly-launched cars by September 2017, and all vehicles on sale by 2019.

A few campaign groups have already speculated that delays in gaining approval could see the WLTP and RDE tests delayed.

When they go live, car makers will have to minimise the discrepancy between WLTP lab test figures and RDE real-world figures to a maximum of 110%, which will fall to a maximum of 50% by January 2020. Currently, the discrepancy can be as much as 400%.

“These results show again that we now need to move forward with the new testing conditions in order to bridge the gap with the lab test,” said Jonnaert.

“RDE represents a tremendous effort for Europe’s car manufacturers, both in terms of investments and production, but our industry will take up this challenge.”