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Discussion Starter #1
Italian consumer group Altroconsumo.it reproduced the official EU test procedure on two cars, and found that, even in the same "controlled conditions", there's something fishy going on.

Golf 1.6 TDI
claimed: 3.8 l/100km
tested: 5.83 l/100km
(+53% greater)

FIAT Panda 1.2 petrol
claimed: 5.2 l/100km
tested: 6.11 l/100km
(+18% greater)


Personally, and looking at things like Fuelly (and working back from there to estimate what a lab test would be), I suspect that the Panda's increase is typical for the industry, but these are the only two cars that have been tested so far. They're promising to do more tests on other models, and also to launch a class-action against VW and FIAT to secure compensation for additional fuel costs.

For the Golf, doing 15,000km a year at Italian diesel prices, that 50% increase in consumption costs over €509 a year... (The panda is €247 a year more on the same basis)

(source, italian: Consumi auto e le bugie dei produttori: chiediamo il rimborso - Altroconsumo
English-language summary: Makers ‘tricking’ motorists over fuel efficiency | Irish Examiner
Video, english subtitles: https://www.youtube.com/watch?v=NjQS_wvL6j0 )
 

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In the UK now more and more I am noticing disclaimers on cars ads, particularly on the radio, something along the lines of real world consumption may not match the figures quoted which are given for comparison purposes only..
 

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Discussion Starter #4
To be clear, this isn't about the difference between the published figures and what an average motorist gets.

The consumer group hired a testing lab, who re-created the official test conditions according to the procedures set out in the legislation. Basically, they were repeating the "controlled conditions" of the original testing to verify those tests.

In such a setting, you'd expect to get a lot closer to the published results than 17.5%. Experimental error, and the way that the car makers run several tests and cherry-pick the best one, means you're never going to get down to the same figure, but it should be possible to get within 5~10% of it.
 

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for too long the motor industry has got away with publishing economy figures that are simply unobtainable in the real world , yet millions of buyers chose cars based on these figures , its bordering on miss selling just like PPi !
 

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I didnt know that Kris, that is shocking!

And although the car industry has obviously stretched things, the consequences of them not are probably worse.

The EU CO2 emissions will be vastly understated using the official figures, so imagine they (the EU) turn around and say, oh by the way Mr Manufacturer, the target of 95g CO2 per km is still in force.... you are saying that your car does 110g CO2 but in reality that figure is 140g CO2 then we will all have sewing machine engines soon...

Oh and expect your VED (tax disc as was) to shoot up several bands aswell
 

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Discussion Starter #7
@Bembo The figures are meant to be a way of comparing one car against the other, and nothing more. At one time, when engine control wasn't very sophisticated, a good test result corresponded with good real-world consumption, but today, it's possible to run an engine extremely lean and still meet the very limited parameters of the test (e.g. "acceleration from 0 to 30 k/m over a timespan of 10 seconds"), but in reality, NOBODY would ever drive their car on the limit of stalling like this.

The public has been very poorly educated about what this test actually is, and what it means. Of course, it's not in the car makers' interests to tell customers that the test results will never be achieved.

The new thing in this story is that even if you duplicate the same controlled laboratory test that produces the unrealistically high mileage figures, a car you buy from the manufacturer will not perform as well as the car that the manufacturer supplied to the official labs for testing. That's not "taking advantage of the rules"; it's cheating.
 

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This is a difficult one. If the rules were stricter, I could see the already woeful (compared to say the Zetec engines of Ford) taxband of my 1.6TS being higher than it is now. Perhaps it is good to be relativistic here and compare not to modern cars, but to the ones they replaced. Supposing the testing has remained about the same over many iterations of the same car, then the relative change may be good.

It is clearly something that is going to have to be looked at soon as MPG is very much the 'in thing'. I am used to teaching people in cars, and it is no wonder the manufacturers get away with this. it is a common experience for me where the same people who just want an ultra efficient car to get from A to B often know little about the car anyway, and are seldom interested in learning. I've even met people who are very impressed with the apparent mpg, yet know nothing regarding the engine.

I guess it will be the same story all over again with electric cars. The figures will always be assuming your car has just left the factory and you live on a lightly sanded monopoly board with the world's best eco-tyre.

I can hardly see the 1.6TDI/CRDI/CDI/CDTI/ owners club getting together and petitioning the EU any time soon...
 

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Old car tests werent fudged though...

My GTA official consumption 23mpg......... I get 28mpg
My previous Giulietta official 60mpg..........I got 50 mpg (average)
 

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Hmmmm......

5.2 ltrs per 100kms is 52.6 mpg in the old money. 6.1 ltr/100km is 44.7mpg.

44.7mpg from a Panda 1.2 sounds a bit careless.. :)
I had a Panda 1.2 for a week and I managed 52mpg. The computer was showing 55mpg occasionally.


If FIAT want to hire me to drive their contender, I'm available (for a fee.. :D )


Ralf S.

Previous ability to get the quoted mpg depends on many factors and might have been a complete fluke. Ralf S. makes no guarantee that he will ever be able to reproduce the feat.
 

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Discussion Starter #13
Nobody. You're missing the point. This is not the usual "the spec-sheet says 48mpg, I only get 35" complaint, but rather "the spec-sheet says 48mpg, but we re-staged the exact same test, and only got 36".

The first compaint is easy to explain. This is the test cycle. Look at it closely and tell me if you've EVER driven like this?
(image)

(Note how the acceleration in the urban cycle never exceeds +3km/h per second.)

The only worth of this test is that, in theory, every car is subject to the same test, so a more efficient car will perform better on it than a less efficient one. Because the test is constant in this way, it can be used to judge the cars. That's its only value.

So, if you buy a new VW Golf, 1.6 TDI of the exact specification that was sent for testing by VW, and you run the test yourself, you should get the same (unrealistic) combined consumption figure out of it. Right?

Until now, nobody has done this. Once they did, the very first two cars they tried were found to both fall significantly short of their published figures. How much of a margin of error do you want to allow for the independent lab's experimental errors? Maybe FIAT can try to hide behind a defence of "experimental error" (and I'll bet that's what they'll do), but VW's explanation should be much more entertaining to read..
 

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My point is partly that the test car is not really driven and BMW are known to send non representative cars anyway. My car has 18" wheels most of the year but fuel consumption improves significantly when it's got 16" wheels.
 

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Discussion Starter #15
the test car is not really driven
I wondered about how they recreated this part of it, because, as as far as I understood it, the throttle controls are normally run by a computer during the official tests rather than a human driver.
BMW are known to send non representative cars anyway.
I think it's safe to add Volkswagen to that list.

I've a hunch that no manufacturer's car would get within 110% of the published figures if the test were repeated on a retail car. The original article (in a PDF from the italian link) notes that applying all of the allowed variations, for tyre-pressure, oil viscosity, etc. could account for a 7% error at most.
 
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