posted 5 years ago

Motor Manufacturers Manipulating Tests For Better MPG?

How Motor Manufacturers Could Manipulate MPG Tests

Motor manufacturers could manipulate tests to produce lower fuel consumption and emission figures than motorists typically manage on the road, a pressure group has claimed. Transport & Environment has, therefore, revealed the techniques manufacturers could – but do not necessarily – use to maximise efficiency. These include placing tape over bodywork indentations to minimise aerodynamic drag, changing the wheel alignment to reduce rolling resistance, utilising highly efficient tyres, installing lubricants which improve engine efficiency and disconnecting the alternator. Realigning the brake pads can help too. Despite these techniques manufacturers have – according to the RAC – claimed that “laboratory tests offer a controlled base for consumers to compare models more effectively than real world driving conditions”. The RAC has also revealed that a new car typically averages 56.5mpg whereas the pressure group estimates 45mpg is more realistic. Either way, new tests from 2017 should ensure figures accurately represent ability. Clearly, it is in manufacturers' best interest to achieve the best possible test results. These, of course, help attract customers. Furthermore, forthcoming rules will ensure that a company's fleet must – on average – emit carbon at a rate no higher than 130g/km by 2015. Many hit this target already – some by creating zero emission electric cars as a means of counteracting their more polluting models. Clever, but perhaps sneaky. 

How Fuel Consumption Is Calculated

As things stand, a car's fuel consumption figures – assuming it has a traditional internal combustion engine - are calculated via the urban/extra-urban tests. These are performed once it has covered at least 1,800 miles so the engine is properly run-in, i.e. at its most efficient. The urban test is performed on a rolling road in a laboratory that has an ambient temperature of 20°C to 30°C. Furthermore, the vehicle must have been stationary for several hours so that the engine is cold. The test requires the subject to perform a series of accelerations and decelerations. It must also maintain consistent speeds and idle while stationary. Within these manoeuvres the vehicle's maximum speed is 31 mph, it averages 12 mph and covers 2.5 miles. In contrast, the extra-urban test represents faster routes such as a-roads. This is performed immediately after the urban test and once again includes a series of accelerations/decelerations, etc. However, the vehicle's speed rises to 75mph and it averages 39 mph over 4.3 miles. The combined figure is then calculated based on cumulative results. Such figures – despite the justified concerns – can be achieved away from the laboratory in certain circumstances. This is evident from the MPG Marathon where cars often beat their official figures on real roads. 


My xsara picsasso 1.6 8v does pretty much the stated urban and extra urban mpg it says in the book and on motorways even a bit better than stated. Old mk6 escort 1.4 was horrendous. But rover 600 diesel would do 60mpg and around 64mpg on svo.

Bought my Nissan Juke on CLAIMED MPG and after ten months of careful driving can not get anyware near claimed figure.Must be at least 15% out.

We all understand this goes on but wha concerns me is that my on board computer in a 2008 BMW 5 series consistently tells me I'm getting a much better fuel consumption than I am actually by about 10%! - what's going on there? this is computer v fuel pump- over a 4 year period NO EXCEPTIONS

I fully agree with Vernon Tyler. The politicians are all in it Together, as David Cameron admitted.

I have a new ford focus 1.6 diesel whicjh claims an average of 68.5 mpg after 13,000 miles including about 20 round trips of 200 miles to Birmingham on motorway and dual carriageway it still only averages 47.2mpg thjese claims should be illegal ,if asda sold a pint of milk wijh only 1/2 pint in it they would be prosecuted

I see no mention of wind speed. The drag due to the flow of air over the car and under the car at 70mph is very significant. Also very few modern road journeys have no hills. How are these represented in the tests?

Not sure of the advantage gained by taping over panel gaps if the car is on a stationary rolling road

So a modern car typically does 45mpg.My 12 year old Ford KA betters that and so does my 50 year old Austin A40.Why then are manufacturers fitting expensive computers,lamba sensors and other electronic equipment which have not improved efficiency but have decreased reliability and only increased expense?

There is only one laboratory fuel consumption figure I am interested in and that is one that will prove beyond doubt engines are becoming more efficient and one manufacturer is being more successful than another; pounds of fuel per hour per brake horse power, the standard measurement used on dynamometer testing that allows the efficiency of different sizes and types of engine to be compared. All other fuel consumption and emission figures should be made valid by being independently made outside the laboratory using average drivers on average journeys and averaged between several cars that each have already completed various real life mileages. Testing on a new car over such small distances can never be relevant to the real world and the government must be stupid, gullible or have vested interests in order to accept such results and make them "official". Call me a cynic but I believe the marketing industry is like politics where lying by omission and putting the best possible spin on things to fool the public and mess with their heads is merely business as usual... Any new car can only ever be as good as the oldest surviving model of its type.

Do these tests take into account the extra weight the car will carry ie: shopping /kids/dogs etc. Or is it just tested with the driver only?

these figures produced in a lab, dont take into account the way different people drive nor what you may encounter on roads

just done a 600 mile round trip mainly m/way. car trip shows 39.8mpg at average speed of 45mph in my 1 year old cascada(3500miles), vauxhall says it does 44

If the test is done on a rolling road how do they allow for wind resistance?

the figures work both ways.... I live in semi-rural lancashire and have always (almost) exceded the published figures. one notable journey, in mid summer, was southport to mabelthorpe... A roads through manchester and over woodhead pass, in a mercedes vito van... published mpg 36 at best.. my mileage (return trip in one afternoon) 41.8mpg... normal oils etc, 1/4 tonne loading but with pure sunflower oil as fuel. As for the "almost" comment on mpg... my fathers escort 1.6 vtec... never got over 24mpg from it and often as low as 21... always with me driving my father (I'm fat, he's skinny)

My wife has just got a new Megane st. It claims 80mpg overall. I can just manage 60mpg she gets about 48mpg. Yet all the VWs I have owned do what they say in the brochure or better. How can Renault get away with this?

Just a thought about the people saying they buy their fuel in litres. We all do, but do you know how many miles you drive a week and how many kilometres? All our road signs are still in miles, so unless you want to do litres / mile it is still MPG.

What the hell is a gallon? I buy fuel in litres and I'll bet you do too.......

The real world mpg figures not living up to government figures is something we hear every day at FlashRemapping. Fortunately we are able to improve fuel economy by quality remapping of vehicles ecus, sometimes up to 20% improvements but more usually 10-13% improvements common especially in turbo diesel vehicles. Big fleets such as BT fleet have embraced this technology and are saving £4m + per year by having their commercial fleet remapped

We are all suffering from government nonsense regarding CO2 emissions. The carbon footprint con is very lucrative but the serious pollution is caused by diesel engines.

do your own test which is simple to do really all you got to do is fill your tank up{from empty is best} zero your milage on trip switch then go on a run say from london-birmingham when you get to birmingham fill your tank back up not forgetting to see what milage you have covered since last fill up then do the maths and that will give you an idea of what you are getting per gallon

Had a 2.2d evoque said you get 41 mpg at best 32 mpg ,it has now been replaced with a cayenne which has got 3ltr engine and bigger and getting 36/38 mpg

My old 2000 Focus 1.6 Zetec averages 42mpg and has done since new over its 120k life. Our newish 1.24 Fiesta Zetec, over the 10k miles so far, has been lucky to reach 40mpg and that is brim to brim. Ignore the computer figures, as they can be 4mpg optimistic, We bought the Fiesta partly because of the claimed 50mpg consumption - Doh!

What a surprise. Being conned by manufacturer's. It could never happen. Yet another one on a long list.

It is time the government admitted that Hybrid and battery vehicles do not achieve the claimed economy figures in real life

I have a Peugeot 3008 and on a run I get 60mpg so I am not complaining

Standard tests are just that - standard. The whole government road fund duty rates are based on the standard tests, so don't knock them too much! Sneakier tricks include oil in bearings insread of grease, among others. Carefully selected vehicles for testing will never be representative of the whole sample population. It is simply that Joe Public is too trusting of anything they read because they have no idea how to properly interpret the results.

The current test is not fit for purpose. Just look at the figures obtained for hybrid cars. In real life many fair worse than non hybrid. It's time for this deception to end.

I have a BMW 116D, the claimed fuel figures are simply a con, there is no other word to describe it. BMW claim over 60 MPG, no matter how I drive, I only get between 42 and 46 to the gallon. I even returned the gar to the dealer, only to be told, "thats about right", so if thats about right, how are the manufacturers getting away with what is in effect a lie? The reason I bought this car was for the fuel economy, my 55 plate Astra 1.7D is more economical, 45 - 60 MPG is normal, and thats an older car, mind you, at least the metal has some substance, the BMW is so thin, its like paper, new cars are rubbish in my opinion, I will in future drive old cars, so had better hang on to my 1999 BMW 5 series, which will do at least 36 on a run, even more if I drive at a very mind numbing 55 MPH!

All a 'con' like everything else connected with the motorist....why don't we just get basic, abolish road tax and add a bit on to fuel as do the French. We also need to get rid of the EU dictating to us about mooring (and other) legislation and bring some sanity back to this Country. Sadly, the EU Referendum will never happen - why not have it right now? - as IF "Mr. Slippery" does get re-elected it will be twisted by a vague offer of more control back to us.....just think how we might bring sanity back to motoring if the EU were not dictating to us.

I use the US city and highway figure when looking at cars and this always seems to be pretty much spot on (remember to convert back from US gallons). The main problem with the euro mpg figures is people don't understand them. They take the figure for extra urban and combined and don't realise that 4 miles of the 4.3 miles is done at 33mph, so get a bit miffed when they don't get the figures sat at 70mph. But then so many buy diesel still when not only is it no cheaper, in many cases can work out more expensive. I have had a few cars with both petrol and diesel, 330d vs 330i, 530d vs 530i, 535d vs 335i, 3.0tdi a6 vs 3.2fsi A6, E320 vs e320cdi, and recently the A3 2.0tdi and 1.4tfsi, and the petrol has only ever worked out around 10% more at worst in in some cases 535d vs 335i and 3.0tdi vs 3.2fsi the petrol has been more economical on sub 20 mile journeys and thus more economical overall. I do around 30-40k miles a year and worst case it costs £30 a week more in fuel, for someone doing 10k miles year it is a non issue. I think if we used the US figures we would go back to buying far more petrol cars again, because you see there is often less than 10% in consumption between the two.

The tests are a base level for you to compare to other cars and nothing else. It really is the only way carry out these tests as if you actually took the car on the road to get the figures there are thousands of variables to affect the figure and as such is unrepeatable

i have a peugeot 106 van i have owner 11 years now, should return 60 mpg, it does in fact return over 50 mpg on normal driving so that is not bad really. but i do agree many of the mpg figures quoted are a long way out, has anyone tried returning a vehicle as not fit for purpose for this reason should have a good case?

Why on earth are they still using MPG? We stopped buying gallons 30 years ago.

We all know the 'official' published MPG cannot be achieved, so why can't the test be changed to reflect 'real-life' driving a world of deceit and corruption its about time that we got true, honest information.

I have an Audi A4 S Line Avant with a 2 litre diesel engine that has consistently returned between 35% to 50% lower fuel econonomy than Audi published figures. The Audi dealer admits the fuel economy performance is "normal" for this car.Yet they still publish the higher fuel economy rates! Seems to me fraudulent claims are being made. I would not have bought this car if I han known the "real" fuel economy performance!

Isn't it only natural to prepare carefully for a test, to be in the best possible condition, to achieve the best possible result? People do it all the time! The tests need to relate to the EXACT model, perhaps even cars taken at random & with so many cars having computers/black boxes if we are serious about this then we could actually collect the data anonymously and report it accordingly. But then if you wanted to know what real life fuel consumption was like you'd check a site like fuelly. But then with more and more alternative fuel vehicles around we need some realistic way of comparing the cost of energy consumption for all vehicles.