‘I went to court when my car didn’t meet its mileage claims’

“these figures are still used in marketing”. As I understand it these figures, but only these figures, must be published by the manufacturer according to EU regulation. Anyone know differently?

The salesman lied to me, Malcolm. I gave him the opportunity to let him say that the figures he had quoted were just the test figures and not what I had asked for.

Why do you think it is acceptable for a manufacturer to specially prepare a car so that it returns higher fuel economy figures than most motorists could achieve?

As I said above if you are given false information about fuel economy by the retailer they should be held liable. The fact that the EU test cycle allows manufacturers to prepare vehicles is the fault of those who published the standard, not the manufacturers. You need to remember that these tests are designed to produce comparative figures, not real life, and they will remain comparative if they are carried out on the same basis. Out of interest what preparations in particular have a significant effect on the results that will give any one manufacturer an advantage?

Criticism might be levelled at the EU don’t you think? Unless we find out facts to the contrary.

Malcolm – As far as I am aware, it is standard practice to carry out tests on actual production samples when independent test laboratories are involved, so I don’t see why car testing should be any different. As John has pointed out below, you cannot have comparative figures if different manufacturers modify their cars in different ways. I read that one manufacturer even reprograms the engine management computer before tests are carried out. I don’t know which particular preparations will push up the official mpg to the greatest extent.

I have not paid much attention to criticism of the current EC testing, but even if there are fair criticisms these in no way justify the manufacturers preparing their vehicles so that they perform better during tests. I believe that most people would regard it as dishonest to prepare a vehicle to enable it to produce better fuel economy figures.

What if I – as a customer – was to prepare a vehicle while the salesperson was out of the showroom. I could switch the price label, put in a spare wheel and a set of car mats, and then innocently say that I would take that car. 🙂

I can’t understand why people blame the vehicle manufacturer for (a) complying with the EU regulations and (b) aiming for the best result under those rules. Doug did have the right idea when he asked the salesman to confirm he would be able to achieve the published figure. Don’t expect one manufacturer to quote “realistic” figures – after all we all use our vehicles in different circumstances. And who would go to the manufacturer who says my equivalent model does 15% less miles to the gallon than anybody else quotes? Be sensible, just use the published figures for comparison and ask the seller to confirm what economy you are likely to achieve in practice. I think we would all be amazed how quickly the vehicle retailers in Europe would force a change in the EU rules!

If you modify a vehicle so that it performs better in a set of tests you are using ‘unfair means’ to obtain an advantage over other companies. I have borrowed that term from higher education, where it is used as a euphemism for cheating.

Would you trust Which? testing if manufacturers supplied products? I would not because of the risk that they might be carefully checked or even modified, so that they were better than what you or I could buy in the shops.

What is wrong with honesty? It could be a powerful marketing tool.

Testing of products that feature in Which? reports is, I believe, done on products purchased in the same way that you or I would buy them. I can see various benefits of this and I trust Which? testing, even though I would prefer to have more information in many cases.

Why should car manufacturers be allowed to prepare their cars before testing? Why not just test cars exactly as they are sold to the public?

In practice it would be very difficult for a manufacturer to guarantee that any given customer will get the same fuel consumption as any given test result because driving conditions can vary so much.

However, it ought to be possible for a retailer’s service team to check that a given car is performing within expectations for the make and model of car.

In my day job, I sometimes get to do long motorway trips on using newish (hired or leased) examples of medium sized and large cars. If diesel powered, I can usually get about 60-65 mpg on such trips. (This does involve driving at sensible speeds within the prevailing speed limits.)

However I doubt I would get anything like as good fuel economy if I was only using these cars for a series of short “social domestic and pleasure” trips across town or even on the motorway, if I were running late and had a plane to catch.

When shopping around for cars that I might actually buy, I do hope that published mpg figures will provide a fair basis of comparison between models but I do not necessarily expect to be able to exactly match the official test figures in my own use.

John, in the previous conversation I did give some % figures in response to particular items – of the order 1 or 2 %. If you put NEDC into a search engine you will find some critical analysis of the test with the sort of “loophole deviations” that might be expected. I do not see that these have a major impact on the comparative results to significantly effect ranking. It is important also to remember the tests seem largely aimed at establishing comparative emissions – principally used in the UK for VED, company car benefit-in-kind tax, congestion charging and, I believe car parking permit charges in some boroughs. It could be argued that if these are on the optimistic side they are of benefit to motorists – but I won’t! However, it needs to be emphasised these tests are not claimed to produce real-life figures.

I can see what you’re saying Malcolm but I think you are underestimating the reliance that many people place on the m.p.g. figures. In this Conversation we know that they are not real-life figures, or really any more than a rough indication, but I expect some people take them as gospel along the lines that “they must be meaningful if every car advert has to include them” and “if they’re not meaningful why publish them”. And I don’t think we should overestimate what most drivers think about emissions data unless they have a direct interest in their money-saving properties. I agree with you that the EU, not the manufacturers, are at the root of the problem; nevertheless manufacturers should not game the system even to the slightest extent. I would guess that leaving out the spare wheel and the tool kit, and firming up the tyres above the recommended pressures, would make a significant difference to the performance figures [otherwise they wouldn’t do it]. Today I’ve been de-cluttering our car and taking out the Winter kit; it’s surprising how much dead weight we’ve been hauling.

Advertised “Official Fuel Consumption Figures” are accompanied by the words “The MPG and CO2 figures quoted are sourced from official EU regulated test results. These are provided for comparability purposes and may not reflect your actual driving experience.” I presume this is officially dictated phraseology and, like the figures, the only information the manufacturer is allowed to publish. Perhaps the caveat should be made much stronger and direct. We are notoriously bad at reading the instructions until all else fails!

As regards the tests themselves I imagine the manufacturers are less concerned with fuel consumption but with emissions. These are used for taxation and other revenue – earning purposes by states and are not only artificially derived – by the driving cycle that does not represent real life – but artificial in the sense they end up as bands with different driver-charges moving from one band to another, rather than a sliding scale. It is therefore an incentive for the manufacturer to do all it can to just get into one band, rather than the higher one. This is always the difficulty with banded charging regimes – like making your income tax affairs avoid as much in the higher rate band as you can.

Modifying a car so that it will produce lower emission figures during testing is cheating.

Testing should be done independently, by people that can be trusted.

wavechange, you miss the point. The NEDC is a defined driving cycle (speed / time / stop start) that manufacturers must use to get type approval for their vehicles. One requirement is that manufacturer’s fleet must overall meet an emission target (currently I think 135 g/km). Therefore the vehicles will be developed to meet this objective. If you know that vehicles tested fall outside the requirements of the test specified by the EU then that would be cheating. Perhaps you would supply examples.

The NEDC test is somewhat lax and allows – inadvertently – some variations in testing but nothing I have seen is likley to give a subtantial advantage. The new test regime learns from these “loopholes” and as and when implemented will produce a driving cycle much more representative of EU countries driving. Although you wonder whether that will be different in 5 years!

It is important to understand the difference between “claimed mpg” and the NEDC issue. The latter was introduced long ago when car technology and driving conditions were very different. It appears that a result of this is it can give fuel consumptions that are further from reality than when originally introduced. This is a consequence of the test cycle, not cheating by manufacturers (who do exploit loopholes, which is not in the spirit of the tests, but does not seem to cause the large disparity)

Standards need to be carefully thought through and written to ensure consistent and sensible results are obtained. The new one seems much better. It will probably be 2020 before it is used as the sole test – NEDC will be used until then. However CO2 targets are being reduced, irrespective of the test cycle, to an objective 95 g/km so it does produce results.

I don’t think it’s me that’s missing points, Malcolm. You can call it ‘exploiting loopholes’ if you want, but I will continue to call it cheating.

We can agree on cars producing lower emissions. They are safer, more comfortable, quieter, more pleasant to drive and much more economical.

You’ve probably been a naughty motorist and carried passengers!

Here’s an example of consumers’ organisation that has taken action against a couple of European companies.

Can anyone think of a good consumers’ association that might be able to take this on in the UK?

Sorry about that, Andrew. I don’t know why I was able to read the article earlier today. I don’t normally post links to the Daily Mail but this is the same story: http://www.dailymail.co.uk/news/article-2766915/Revealed-The-car-makers-tricks-boost-MPG-claims-leave-drivers-forking-400-year-petrol.html

There’s no shortage of press reports on cheating by car manufacturers: telegraph.co.uk/motoring/news/10803684/Car-buyers-lose-out-in-fuel-test-cheating.html#disqus_thread

It makes no difference if a car is specially prepared to produce better fuel economy figures or if the cheating goes on in the test itself. Either way, it is dishonest.

There are indeed very big differences between what a motorist will achieve and the EC NEDC tests. As has been said before, the official tests are obsolete. Every driver must be aware that how they drive affects their fuel economy, and with a digital display of mpg on modern cars, the fact is inescapable.

I have seen figures quoted for the effect of various preparations used by manufacturers to inflate their fuel economy figures but there is no way of being sure how these modifications will affect a particular make and model in a test. I suspect that the combined effect of the small percentage improvements works rather like compound interest.

Why not tell all manufacturers to stop all modification of cars prior to the EC NEDC tests?

If it is motor cars Honest John is the place to look.

I note that there are sixty thousand real life stats on MPG. And the derived figures from all the reader loaded data are compared to the Test figures showing how far out they are ! But then it tells you why.

” Why the EC figures do not represent true MPG
The prescribed EC test is a lab test carried out to simulate a mix of different types of driving and arrive at ‘combined’ CO2 emission and fuel consumption figures.
Because vehicle taxation in Europe is now based on CO2 emissions, manufacturers naturally optimise their engines to achieve the lowest possible CO2 in the tests – this skews the true MPG.
This gives a correspondingly low fuel consumption figure. Unfortunately the relevant EC Directives prescribe that this figure and only this figure can be publicised by manufacturers, even though it is unlikely to be achieved by the average driver in real life conditions.”

I have no problem with manufacturers seeking to achieve the lowest possible emissions figures. That is to be commended.

It is unacceptable that they prepare their vehicles before the tests so as to achieve better figures than they would do if the tests were carried out on unmodified vehicles, as sold to the general public. Is that too much to ask?

The point is, when the official fuel consumption figures become the received wisdom of the motor traderes, those are the figures they will blurt out when a customer asks the question. That’s what happened in Mr Clement’s case and it has probably happened every day for years. Car salesmen are on a bonus for every sale and having met a number of them [and they are all men – the women’s role in the dealerships seems to be to make the coffee and rearrange the magazines] I wouldn’t expect them to do any more than parrot the tests results and say nothing about their imperfections as an indicator of real performance. The buyer has do their homework and use websites like Honest John and motoring magazines to get closer to the actuality. Unfortunately, on this issue, the EU burns a lot of fuel and takes a long time to get anywhere. Like every schoolboy I used to cook my conkers before a contest; it’s natural that car makers will do the same if they can get away with it. The important thing now is to make sure car buyers realise that the official figures are faulty and not fit for the purpose for which they wish to use them. Disappointingly, according to what Diesel has posted above, they don’t seem to be much fitter for the other purpose for which they are produced, namely emisions. Malcolm suggests that the differences in performance caused by modifying the vehicles tested aren’t all that significant and don’t distort the overall rankings; I am not convinced, myself, because there is no way of knowing.

John – What is the point in publishing fuel consumption figures if manufacturers use various ways to artificially improve them? Since manufacturers pick different ways to prepare their cars, the value of the tests for comparative purposes is debased. It seems clear that the difference between the published figures and what the motorist achieves is growing.

No-one has given me a reason why tests should not be carried out on unmodified vehicles.

I completely agree with you. The official fuel efficiency figures are a “trade misdescription”. These Conversations prove that – we are debating whether it’s this or whether it’s that. The problem is it’s not possible to just stop publishing the figures; they exist, and car owners and buyers want to know them. If I understand it correctly, the NEDC results are the only figures the manufacturers are permitted to state in any advertising and in technical specifications and data that they produce. This is makes no sense. What I am not at all clear about is what a car dealer can say to a prospective purchaser about fuel economy. I suspect they are not so shackled and could offer an “illustration” of the typical performance likely to be achieved under the kind of driving conditions that correspond with the purchaser’s experience according to reputable research. Still quite vague perhaps but probably more useful. It would not be a daunting task to compile comparative tables and make them available across the industry; most dealerships only handle one or two marques so they would not have to spend a fortune acquiring the data for the specific models they sell. I suspect that the relationship between the manufacturers and the traders makes any of this practically impossible.

It would be interesting to know what the Society of Motor Manufacturers & Traders thinks about all this. In the interests of consumer knowledge, which is power, it is important that the discrepancies are publicised and that car buyers are pointed in the right direction to find useful information.

The reason that no-one has given a reason why tests should not be carried out on unmodified vehicles is no doubt because there isn’t one. Why such a massive element of the overall European economy [with significant implications in the case of vehicle imports], and such an important part of EU citizens’ lives, does not have a reputable and independent car testing establishment, with standardised inputs and outputs, beats me.

I don’t know how we will move on, John. I suspect that until the new tests are implemented we will continue to be fed worthless figures. We need consumer organisations across Europe to unite and ensure that preparation of cars to improve fuel economy figures ceases forthwith.

John, “The reason that no-one has given a reason why tests should not be carried out on unmodified vehicles is no doubt because there isn’t one.” As discussed elsewhere as far as I can see the modifications allowed by the laxity in the EU standard do not give substantial reductions in mpg or emissions – nothing like the large differences that appear between the artificial NEDC test cycle – outdated – and “real life”. The culprit seems overwhelmingly to be the test regime. If someone has evidence to the contrary then it would help this conversation move on – and perhaps manufacturer-bashing could be done on a sounder base.

I don’t know how much closer to reality the new standard will be when it eventually yields figures. But in practice single values will never represent reality; a range of values for mpg within which say 90% of drivers should fall is to my mind the only sensible way to present useful data. The new test will not do this, so will always be for comparative purposes.

It might be more constructive to have all those who collect real-life data across Europe – from drivers records, not from test regimes – to pool and publicise the results and produce an on-line data base that purchasers can access. That should satisfy those who want to establish likely costs, while the EU tests can be recognised as producing data for comparative purposes; the two objectives should not be confused.

I have assumed that the motor manufacturers, who virtually control the dealerships, would not be very happy to see the unofficial and realistic figures presented to car buyers. That is why I advocate publicising the alternative sources of data. After all, not all car buyers are canny Which? readers and dealers are trained and incentivised to steer them into a purchase with an element of economy in the information given.

We will never get perfect comparability in fuel efficiency statistics but we can at least try to stop the weighted results caused by modifying vehicles before test. Just because manufacturers can do it doesn’t mean they should. I am mindful that the CBI recently called for companies to earn more trust from the public. Well, here’s a starting point for one of our biggest industrial sectors.

Many people are indifferent to fuel economy figures but for just as many it is possibly critical. The consumer organisations must continue to press the EU authorities to get on with implementing a more sensible test regime with minimum delay, urge the EU to put an end to anything, however apparently insignificant, that compromises the trustworthiness and value of the NEDC tests, and tell the public what the data really means and how in its present form it is unhelpful.

Andrew, thanks for providing this information. If the implication is that the manufacturers did not follow the test procedure and gave results, as a consequence, that were effectively falsified then they should be prosecuted. Is this what was alleged to have happened?

The NEDC test does, because it seems carelessly constructed, give leeway in the way cars are prepared for testing. One report I have seen suggests that between 2002 and 2010 the reduction in CO2 emissions overall was around 30%. Of this it was estimated 20% was due to technological improvements – so a real gain under the test conditions – whilst 10% on average could be accounted for by using the imprecision in the tests specified if manufacturers chose to do so. Under the proposed new tests many of these have been removed so hopefully more realistic and comparable results will be reported – in around 5 years!

Given these “loopholes” that give rise to so much criticism you have to ask why the EU has not acted to close them by modifying the standard.

I do not think we could ever use an artificial test to predict sensibly what real drivers will achieve, as they will inevitably cover a fairly wide range of fuel consumption for a given vehicle, depending upon driving style, load, journey type and terrain for example. Will Which? consider supporting a European database from driver reports – extending e.g. spritmonitor – that we are advised to use to check “real life” consumptions?

The BEUC report kindly provided by Andrew relates to the same cases as the newspaper articles I referred to earlier. It seems unlikely that the companies will be prosecuted or the unfortunate owners compensated.

Every motorist needs to know how manufacturers are preparing their cars for the EC NEDC tests, thereby producing false data that will push up the costs of running a car. I am surprised that ‘Honest John’ makes no reference the cheating that has become endemic in the motor industry.

This BEUC report more or less states what has been said elsewhere – that the EU NEDC test is well out of date with respect to current vehicle technology and driving habits and is lax in certain of its test requirements. You have to put much of the blame for this at the EU’s door and ask why they have not dealt with it.

If Altroconsumo has evidence that Fiat and VW have produced consumption figures by testing other than in accordance with the standard then they should be punished. As the EU relies on these results to meet its CO2 emissions targets I presume they would impose hefty fines.

If however Altroconsumo is simply accusing VW and Fiat of producing misleading consumptions by publishing the only figures allowed by the EU, and if these have been produced in accordance with the standard, then I do not see what their case is. It will be interesting to see how this develops.

I still want to know if the new standard is being delayed and, if it is, why. Meantime I still suggest we need a reliable database from drivers reports of real life consumptions that we can all access to see what we might achieve. A standardised test procedure is no substitute. I hope Which? might comment on supporting this.

There is no reason why any car should be modified prior to testing. Like cheating in the subsequent tests, it is falsifying the results. Perhaps those who devised the NEDC tests should have specified that vehicles must not be prepared in a way that would improve fuel economy or emissions figures.

Since vehicle testing is not carried out in independent laboratories, we cannot be sure how long the manufacturers have been modifying their vehicles prior to test, or which manufacturers are using which tricks. I do not know why the testing protocols are so out of date, but my understanding is that it is the manufacturers that are keen to delay implementation of tests that are more relevant to the 21st century.

Maybe Rob Hull could tell us how vehicles are prepared before testing for Which? I expect that the tyre pressures are set as recommended in the makers’ handbooks and the engine warmed up where specified. I very much doubt that the doors will be taped up or the tyres over-inflated.

Thanks Rob. That’s what I would expect from Which?. I would expect manufacturers to do the same.

Rob, your link states “All manufacturers follow the same test procedure, but can select any accredited lab to use for the test. It’s very hard to get truly repeatable and comparable results when using multiple labs.” I am a little surprised at the inference here – that your lab results may not be replicated by another lab. This means your lab may not give representative results then?

My experience of testing to EN and worldwide standards is that they tell you the tests you must undertake, the way the tests should be conducted and specify the key characteristics of the test equipment used – precisely to ensure that results are as repeatable and comparable as possible.

For example when carrying out a test for water ingress, the size of the water nozzle, the precise shape of the cavity behind it, the water flow rate and its temperature, the distance the nozzle is held from the test item, the temperature and preparation of the test item….etc…are all specified.

Are you saying that the NEDC test does not specify the test equipment and its operation?

Oops – My post above was a response to Malcolm’s post below.

wavechange, I have had experience of independent test labs – these are often profit making organisations. Your total faith in them is misplaced – they depend on the quality of their personnel, and their investment in equipment. It is not the ideal world you might think.

I have been told this by one of my former postdocs, who went on to run a government lab in what used to be called county analysts. I don’t have total faith in independent labs any more than I have total faith in assessment in higher education, something I have had direct experience with.

Independent testing remains the best respected approach and if the gold standard is tarnished then action is needed to rectify the problem.

Whatever the shortcomings of an independent lab, I hope they would not prepare cars for testing by taping up the doors, swapping and over-inflating the tyres, and so on.

Given the volume and economic value of the European car industry [including imports] I should have thought it would be cost-effective to establish an institution that could undertake the testing on behalf of manufacturers. At present manufacturers are put on trust to test their vehicles in accordance with the terms and conditions of the New European Driving Cycle [NEDC] but, other than the company’s own quality assurance system, there is no external validation of the test conditions and the results. Introducing that might be a worthwhile interim measure to boost confidence in the tests. I am sure that the personnel in the companies’ test workshops will strive to ensure that the highest scientific standards of compliance with the NEDC rules will be applied but, as we all know, commercial pressures can lead to contrivance and there would be much merit in applying a degree of external rigour to the process.

One of my personal desires would be to ensure that motor cars can last longer before being scrapped. I feel that every five years we should achieve the addition of one extra year to average longevity of the overall vehicle fleet as a result of design and product development. Anything that would harness the advances in performance and safety acrosss the industry so they can be applied to existing vehicles, and that enables cars to be retro-fitted to avoid obsolescence, would progress towards that objective. A respected pan-European testing house and research institute could make a major contribution. It could bolster the European manufacturing industry and lead to fewer imports [I am not in favour of protectionism and there is a lot to learn from technological developments elsewhere but we need to keep the playing field level]. This might all be too idealistic, but as Chairman Mao is reputed to have said, “the longest journey starts with a single step”.

John, as I understand it the tests are subject to independent scrutiny and the laboratories are accredited. Accreditation with an international standard against which there activities are assessed is standard for many industrial laboratories.

Cars do last much longer than they ever used to – largely through lack of corrosion of bodywork as well as better manufacturing of the engineered components. My two cars are 11 and 21 years old respectively (we sold the 30 year old car last year) – all in good working order and just MoTd. The main problem is with the new technology modern vehicles incorporate – when that goes wrong is it worth the cost of repair? Partly high component cost, but also high labour costs. The penalty of making cars safer and more energy-efficient.

Thanks Malcolm. Wikipedia quotes Which? [May 2015] as saying that “no official body polices the tests and the car companies can arbitrarily reduce their results by 4% at the end of the cycle”. I have left my May magazine in someone else’s house so I am not able to check right now whether that quotation has been taken out of context.

John, I have seen statements that the tests are independently looked at. I have asked SMMT, one organisation that states this, whether this is true.

The 4% is part of the requirements of the EU test. Not something the car manufacturers arbitrarily do, seemingly. This is in one of the documents –

“UNECE regulation 101 allows extending the type approval to all vehicles within a 4% interval on their respective CO2 emissions. Such provisions were not discussed in the WLPT process” (WLTP is the proposed new test regime).

In another “In addition, the NEDC regulation provides tolerances for some of the parameters that also have impacts on CO2 emissions, for example, tolerances around the speed schedule of the driving cycle (±2 km/h and ±1 second), tolerances of dynamometer control coast-down times (±5% and ±10%), temperatures, differences between measured and official CO2 values (±4%), tolerances of measurement devices, etc.”

The concerns I have, with no links to the industry, are that when Which? looks at topic such as this it gets the facts in front of the readers it is seeking to inform and presents a balanced and objective case. At present the facts do not seem to have been either well researched or fairly presented and I do not want to be misled into a conclusion that may not be fair. So my aim has been to try to find out facts and put them into this conversation. If my “facts” are incorrect then I’d welcome them being challenged – I’m just a layman digging arount the internet and may be reaching the wrong conclusions. But facts are the key.

John wrote: “At present manufacturers are put on trust to test their vehicles in accordance with the terms and conditions of the New European Driving Cycle [NEDC] but, other than the company’s own quality assurance system, there is no external validation of the test conditions and the results. Introducing that might be a worthwhile interim measure to boost confidence in the tests. I am sure that the personnel in the companies’ test workshops will strive to ensure that the highest scientific standards of compliance with the NEDC rules will be applied but, as we all know, commercial pressures can lead to contrivance and there would be much merit in applying a degree of external rigour to the process.”

I totally support this as an interim measure, but in the longer term we need a robust testing procedure that any informed person can understand and will respect as fair.

DerekP, I think the only sensible way of giving drivers a good idea of their likely consumption is a range, as you suggest, within which 90%, say, would fall. These can only be derived, I think, from real life experience – the sort of data collected by e.g. spritmonitor. This data cannot be provided I suggest by the tests set for type approval by the EU – whilst the new test regime is likely to be more like the “average” European driver it is still an artificial test under laboratory conditions. I don’t know how it could be used to give the spread of consumption that a range of drivers would get in practice. I suggest it is left to do its main job – to reduce CO2 emmissions to specified levels and let’s have a separate publicised and independent data base against which we can estimate our own likely consumption.

Your Ford Fiesta might be run on badly inflated tyres, continually fully loaded, in hilly country with a heavy right foot. I don’t see how a manufacturer can deal with a fuel guarantee under such circumstances.

It is well known that manufacturers removing parts of vehicles to reduce weight and return better figures in the official tests, but removing everything bar the engine is truly innovative. However, I’m not sure how you plan to measure mpg if there are no wheels.

There are test cycles that just use the engine removed from the vehicle, aimed at commercial vehicles. However in most cases it is simpler to test the whole vehicle. Remember the emphasis is on emissions, to which l/100km (or mpg if you are an imperialist) is linked.

I see. I thought we were discussing the fuel economy figures. Apart from the VED being a reflection of carbon dioxide emission, I doubt that the majority of motorists car about emission figures. What they want is an honest indication of the fuel consumption of vehicles.

Testing under standard conditions is obviously not going to show what any individual driver will achieve but if the manufactures stop cheating and preparing their vehicles, we might see slightly more useful figures when we are in the market for a new car.

This conversation is about salesman or dealers who deliberately or otherwise give fuel consumption figures to customers that are wrong. Perhaps it should revert to that theme as we have deviated away from it. The questions about EU testing etc might be better continued in the parallel conversation “How many miles can your car really do on a full tank?”. Just a suggestion to keep the themes from being confused.

I think the threads are already hopelessly intertwined and most will go to the “live” thread.!!

The point about testing the engine was to divorce its testing from any confusion in users minds from what a car might get in actual life. Testing as to what a car might do in real life could be run by consumer magazines or auto magazines on their own courses and consumers can take their choice on how far any consensus exists … or not : ) And whose results and reviews they trust.

Given the automated driven car any test track can be run precisely by an AI and for considerable periods so achieving reproducible figures accurately.

Re; The query on running engines without wheels that is actually something that has been going on for decades as manufacturers calibrate for ECU and gear-shifting and measuring torque. To simply run it in top gear or any series of gears to measure fuel usage AND emissions is actually trivial.

I have already made a very on-topic point about how I was lied to by the dealer who I bought my car from. The farce of manufacturers preparing cars to perform better in tests is relevant to the discussion, in my view, since it is the reason that cars consume more fuel when tested by Which? and driven by the general public.

I’m not sure how many miles my car will do on a tank because of the inconvenience and possible danger of running out of fuel. I would estimate 650 miles.

I’m sure our moderators will give us a gentle nudge back on-topic if necessary. 🙂

I would like to know how honest the Honest John website is. To quote from the Real MPG section:

“Because vehicle taxation in Europe is now based on CO2 emissions, manufacturers naturally optimise their engines to achieve the lowest possible CO2 in the tests – this skews the true MPG.”

While it is widely recognised that manufacturers are modifying cars to make them perform better in the official tests, I am surprised by the fact that all we have is a positive comment about manufacturers aiming to achieve low carbon dioxide emissions. Having read the motoring section of the Telegraph for years I have assumed that it is generally supportive of the motor industry.

Drivers’ figures put on this or any other website are no substitute for good quality independent testing under controlled conditions.

wavechange, HJ says on his website:
“Overstated official mpg figures cost UK drivers a colossal £4.45 billion per year in fuel and can result in misery for millions of cash strapped motorists. That’s why we created Real MPG, which allows readers to show how many miles their cars actually do to the gallon.

To date, we have collated more than 46,000 entries, covering all the major manufacturers and models. On average, 87 per cent of cars in the UK achieve their official MPG figures, but some fare better than others.”

Thats more like the hype we like to see, isn’t it!

Figures from “the general public” if collected in sufficient quantity to be a significant sample are the best way I can think of to give other drivers a good idea of the range of consumption they might achieve. It is data from the “general public” that gives the basis on which driving cycles are constructed. I’d rely on such data, just as if consumers associations were to collect data on the trouble free lives of domestic appliances I would use them to assess how long mine might last – better than an artificail test.

I could make the same comment to you, Malcolm. 🙂 It is common knowledge that manufacturers are cheating the public by modifying their cars so that they perform better in the tests. I would like facts about the extent of this cheating, but it seems very unlikely that we will be given them.

If you are happy with numbers put into databases by the general public, that’s fine. I want to see figures generated under standard conditions using unmodified vehicles. People use the official figures. We have both given examples of this.

I would like to know why we cannot ban manufacturers from modifying their vehicles prior to testing.

I see that Parkers guide reckons that a drivers style can affect the mpg between 2% to 20% so I think nitpicking on the margins is probably not that useful given the effects a driver has. Let alone the types of journey, weather, traffic conditions etc.

On Saurday I bettered the manufacturers figures by the odd mile per gallon because I can drive smoothly and by anticipation in built up areas try to avoid any stopping. All of this done safely. Admittedly it was around 11 pm but a mixture of roads and only 18 miles.

The journey down I thrashed the revs a bit and was near 8mpg under for journey. But then at 5 pm with three stops at lights and junctions also. SO overall my average would be near the bottom end of the range. However taking the individual journeys it proves without any doubt that style is perhaps a much bigger factor than removing a wing mirror etc.

Therefore I submit that more accurate figures from the manufacturers derived from a no chicanery tests would still be pretty darn useless . Of course we may all be paying a little more in Road Tax …. ..!

Of course driving style has a big influence, as does terrain, speed and holdups. Every driver will be aware of this. But when the large majority of motorists are getting lower fuel economy than the test figures then it is hardly surprising that so many people are fed-up with the fact. I’m not too concerned about the figures that I achieve, which are nearly 10 mpg better than my previous car, but cheating by the manufacturers to achieve artificially high figures must be stopped.

If all manufacturers test unmodified vehicles then at least there will be a chance that a significant percentage of drivers will exceed the official fuel consumption figures. Many of us are paying little or no VED these days.

“If all manufacturers test unmodified vehicles then at least there will be a chance that a significant percentage of drivers will exceed the official fuel consumption figures.”. Unlikely; it is the test that is at fault as it neither represents modern car technology nor driving in real life. To its credit the Which? May article says “The culprit: an obsolete test”.

Official reports estimate the test is likely to give up to 30% higher figures than are realised “on the road”. The ways manufacturers can exploit weaknesses in the test are unlikely, an official report states, to contribute more than 10% to the CO2 reduction (and consequent mpg or l/100km).

The WLTP cycle proposed should be more realistic but I maintain the best source of fuel consumptions for drivers are data from other drivers collected on properly-managed databases.

The EU tests are primarily aimed at reducing emissions. The EU sets CO2 targets that manufacturers have to meet. If they don’t, the EU fines them.

Malcolm – In the tests carried out for Which? the cars are not modified and the tyres are at the specified pressures – see the recent post by Rob Hull.

I know the current test is outdated, and have done for years. Since we started to discuss this topic I have learned something about the new test, though I still have no idea if the manufacturers are pushing for its implementation.

As I have said before, it is cheating to exploit weaknesses.

wavechange, I am asking two organisations about the alleged delay to implementing the WRTL test. I will be interested to find out. Which? could contact the EU to ask them perhaps? Two possible explanations – but they are not official – are that the EU are setting CO2 targets alongside the new test regime that manufacturers regard as economically or otherwise unachievable in the proposed time scale, and/or that the CO2 targets are siginificantly less than set by other countries (e.g. USA, China, Japan) which will lead to a lack of competitiveness in those markets. Suppositions only but there are usually two sides to any story.

We are aware of the loopholes, or laxity, within the NEDC standard. What we do not know is how far individual manufacturers make use of these, and to what extent. Perhaps you, or Which?, have information about this?

What does seem clear from reports prepared for the EU is that the majority of the “discrepancy” between real life consumption and the artificial consumption provided by the test is due to the outdated test. The impact of what you describe as cheating is what matters in practice and it seems, in theory, to be about 10% of the reduction if manufacturers all took advantage of the test – but unless anyone knows how much advantage they take then this is conjecture. By all means berate them but let us stay focussed on the root problem – an outdated test. I’m sure we wouldn’t want to milslead people into thinking all the problem lies at the door of the manufacturers – unless we have supporting information.

Perhaps we should pause now to see if we get some facts?

Has anyone has claimed that official tests could ever reflect any driver’s actual usage? I often get different figures when I make the same journey.

My concern is that manufacturers are modifying their cars to produce better figures than could be achieved if the tests were carried out by a good independent test lab, and that since different manufacturers are carrying out different fiddles, tests are NOT carried out under standard conditions.

tonyp, This conversation is headed ” I went to court when my car didn’t meet its mileage claims” and the previous one on a similar topic began “Like many motorists you probably have a good idea of how many miles your car can do on a full tank of petrol. But do you know if it is anywhere near what the manufacturer claims?” The inference is that manufacturers are making claims that cannot be met. Whereas manufacturers are not making claims but simply publishing the only figures I believe they are allowed – those derived in a laboratory from standard tests done to an outdated and defective EU standard and driving cycle They are officially declared as not likely to be what you get in practice.

You are quite right – real consumption will depend. for an individual driver, on many factors that a standard test will not cover. We can only hope the proposed new driving cycle will get nearer an average for most drivers; the present one seems, from one source (Honest John), to be around 16% optimistic overall.

In practice it would only be sensible to publish a range of consumptions within which most drivers would fall The EU test will not do this; that must be left I believe to collated data supplied from experience by real drivers.

The theoretical impact on test results of manufacturers modifying their cars, because of the leeways allowed in the NEDC test, has so far been estimated at around 10% of the 30% savings in CO2 (and presumably fuel). To my knowledge no evidence has been produced of what individual manufacturers might have done or to what extent.

Test labs should be using the standard test regime and test equipment of specified performance if the standard is formulated as EN standards normally are to ensure reasonable repeatability and consistency from lab to lab – whether manufacturers’ in house facility or independent.

I’d like to see evidence before I draw firm conclusions.

Yes, Malcolm, I know how the conversation is headed, but the contributions have morphed into the accuracy of test figures. As it so happens, I do know the published information for my car and, since it is fitted with displays of instantaneous consumption, journey consumption and cumulative consumption, I am very aware of the actual values achieved as well as being able to see which driving techniques cause the highest consumption. As I mentioned in a previous post, I find that sometimes I achieve worse figures than those published, sometimes the published figures and even, admittedly rarely, I have achieved better than the quoted figures.

Recent activities have illustrated to me the effects of a series of short journeys in heavy traffic on fuel consumption. For the last 10 months I have been travelling, on average, twice a week to the local hospital for treatment. This is a journey of about 4 miles, but the journey time and fuel consumption can vary quite significantly depending on the time that I am making the journey – the worst case is school traffic in the afternoon – even in the best case, my consumption figures are significantly lower, in the region of 20% less than my more normal usage. With a mix of hospital visits and my more normal usage I find that my cumulative consumption is some 17% lower than it used to be. I think my experience shows the difficulty of providing ‘real life’ figures and the idiocy of expecting dealers to provide a guaranteed consumption performance.

I agree that a quoted range would be preferable to a single figure, but only to those who understand the concept of probabilities. How, for instance, would the minimum figure be defined? Would it be for a sensible driver who just happens to be spending most of the journey time in heavy traffic although driving sensibly or for the driver who has a load of heavy junk in the boot and a roof rack whose driving style is that the right foot should be either holding the accelerator pedal flat on the floor or flooring the brake pedal. If the range were to be such that all situations are covered then then it would be so wide as to be virtually useless.

If the range is based on sensible usage then there will be drivers who fail to achieve the minimum and claim that they have been cheated. It would be possible to assign a probability to the figures but my experience is that most people do not understand this concept, they fail to appreciate, for instance, that a 90% probability of something happening means that there is a 10% probability that it will not. However the figures are presented there will be those who will find cause to claim that they are wrong and that they have been cheated, it’s called human nature! To some extent the concept of a single figure with a caveat saying that it is merely representative and may not be achieved in practice is better than quoting a range with a similar caveat.