Car makers manipulate emissions tests

[leef44]

We hear about drivers not getting anywhere near the claimed fuel efficiency of manufacturers' claims. Back in 1997 I had a Passat 1.9TDi with a claimed 50mpg. I managed 50mpg in that car.

There is no way I could match the claim in a modern day car. This article explains why:

http://www.bbc.co.uk/news/business-21759258

Interesting to see that in 2001 there was a 7% difference between claims and reality. In 2011 that gap increases to 23%

[zax]

Maybe it's time to ditch the mpg or l/100km figures and make the primary measurement a representative "economy index" value instead. Then we can forget about all of this "I couldn't match the official figures" nonsense. Personally I don't care if the figures match the real world, because the "real world" is a huge and infinitely variable place. As long as figures are comparable between vehicles I'm happy.

Not sure how the writers reconcile:

"There is no evidence that the growing gap is caused by changes in the way cars are used and driven"

with:

"Cars are also increasingly fitted with energy guzzling accessories like air conditioning, navigation and media systems, heated
seats, etc. This equipment is not switched on during the test and by omitting the energy consumed, the official test results are
lowered."

Usage of in-car toys is by definition "how cars are used". Simple baseline - if the car allows it to be shut off and the car still operates then it can be shut off for the test.

Working to a worldwide average for this stuff seems silly. I wouldn't expect to get the same mpg here (-22 degrees this morning) as somebody in Death Valley or Cape Town. That said I'm still beating the official figures even with roof bars on so I do wonder sometimes about these "25% worse" people...

[LotusOmega375D]

Here's some 100% truthful MPG data, recorded by myself with a mileage/fuel log over the past 6 years, driving three consecutive manual Passat 2.0 TDis (140PD, 140CR, 170CR).

The vast majority of this mileage was covered at about 70mph on dual carriageways and motorways (i.e. no daily commuting jams, or trips to the supermarket)

Total overall fuel economy for the 6 years April 2007 > March 2013: 44.3 MPG

To be fair the latest 170bhp car is proving to be the most economical at 47.6 MPG (VW brochure claim 60.1 MPG Combined cycle). The previous 140bhp cars were both 43.3 MPG (VW brochure claim 47.1 MPG)

So there's a few interesting conclusions to draw:

1) VW's TDi engine IS getting slightly more economical.
2) VW's fuel economy claims are getting ever more far-fetched.
3) VW has manipulated the test and increased its own advertised MPG Combined cycle data for the 140bhp car from 47.1 MPG to 61.4 MPG and from 44.1 MPG to 60.1 MPG for the 170bhp car.

[Bullett]

I can hit and even exceed the published figure for my Octavia VRS. My wife gets 20-25% less range, so driving style does have a big effect. This is in typical driving, not dawdling but not hooning.

[Captain Muppet]

The gap between the two lines on that graph is made up of car preperation and driving style.

Why is it that the people who make the cars are being blamed for the gap?
Why not the people who use the cars?

[collateral]

Emissions and mpg are two completely different things

[LotusOmega375D]

Captain Muppet said:

The gap between the two lines on that graph is made up of car preperation and driving style.

Why is it that the people who make the cars are being blamed for the gap?
Why not the people who use the cars?

Isn't that the whole point of the article though? It's now no longer possible even for Miss Daisy's Chauffeur to close that gap due to the tricks the manufacturers now employ to massage their test figures, which renders their claimed data worthless, if not fraudulent.

[kambites]

Captain Muppet said:

The gap between the two lines on that graph is made up of car preperation and driving style.

Why is it that the people who make the cars are being blamed for the gap?
Why not the people who use the cars?

The article is arguing that it isn't, unless you intend to over-inflate your tyres, run your engine on specially thin oil and tape up all the shut-lines every time you drive.

[Captain Muppet]

LotusOmega375D said:

Captain Muppet said:

The gap between the two lines on that graph is made up of car preperation and driving style.

Why is it that the people who make the cars are being blamed for the gap?
Why not the people who use the cars?

Isn't that the whole point of the article though? It's now no longer possible even for Miss Daisy's Chauffeur to close that gap due to the tricks the manufacturers now employ to massage their test figures, which renders their claimed data worthless, if not fraudulent.

But it is possible. People in this thread have already said they do it.

Also the data isn't what the manufacturers claim is the mpg you'll get, it's the result of the government test carried out to the government's regulations. All the manufacturer can do is work within those rules.

[Cyder]

Hmm I think I'd be taking that article with a bit of a pinch of salt, especially the comments from Mr Archer.

Government inspectors can and do observe any test they desire. If the manufacturers were buggering about manipulating the tests they'd be in a whole world of trouble.

[DCLXIV]

The manufacturers merely follow the rules laid out by the EU and use any advantage they can that's allowed. They would be stupid not to. At any rate, even without this the actual drive-cycle is completely unrealistic.

Edited by DCLXIV on Thursday 14th March 21:22

[davepoth]

collateral said:

Emissions and mpg are two completely different things

No they aren't. The emissions figures are calculated from the MPG figures.

[anonymous-user]

mpg's quoted on forums are just as bad, everyone always quotes a run, defined by what.

in true engines are very inefficient and whilst they bleed us dry no meaningful money is invested in new non internal combustible engines.

[Scuffers]

davepoth said:

collateral said:

Emissions and mpg are two completely different things

No they aren't. The emissions figures are calculated from the MPG figures.

Actually it's the other way round...

Emissions test is from tailpipe emissions, MPG and CO2 are calculated from that.

[Jonny_]

LotusOmega375D said:

Here's some 100% truthful MPG data, recorded by myself with a mileage/fuel log over the past 6 years, driving three consecutive manual Passat 2.0 TDis (140PD, 140CR, 170CR).

The vast majority of this mileage was covered at about 70mph on dual carriageways and motorways (i.e. no daily commuting jams, or trips to the supermarket)

Total overall fuel economy for the 6 years April 2007 > March 2013: 44.3 MPG

To be fair the latest 170bhp car is proving to be the most economical at 47.6 MPG (VW brochure claim 60.1 MPG Combined cycle). The previous 140bhp cars were both 43.3 MPG (VW brochure claim 47.1 MPG)

So there's a few interesting conclusions to draw:

1) VW's TDi engine IS getting slightly more economical.
2) VW's fuel economy claims are getting ever more far-fetched.
3) VW has manipulated the test and increased its own advertised MPG Combined cycle data for the 140bhp car from 47.1 MPG to 61.4 MPG and from 44.1 MPG to 60.1 MPG for the 170bhp car.

In short, VW are full of st when it comes to economy figures.

I also drive a 170bhp Passat TDi, which VW claim does 60.1mpg, and typically average between 48 and 53mpg over a tankful (calculated from the trip meter and the amount of fuel to brim the tank as the dashboard mpg reading is also full of st!). Best I've ever managed to average from a tankful was 59mpg, and that was an ordeal: 2 weeks and 700 miles of driving like a pensioner. (The dashboard reckoned it'd done 66mpg...)

The 2008 Fiat Bravo (150bhp 1.9 diesel) I had previously, however, typically exceeded it's claimed 50mpg by about 10%, and actually managed 62mpg from a tankful of diesel once (again driving like a pensioner).

Seems to be the case with all VAG cars of late; blokes at work struggle to get even 50mpg out of 1.6 TDi Golfs/Yetis that allegedly should do mid-60s.

[amstrange1]

The point is, the regulations reward the OEMs that can design a car to be more economical over the official emissions cycles. Lower VED and the ability to claim excellent official mpg figures are important marketing attributes for the OEM.

The problem is, the gap between NEDC official figures and 'real world' mpg widens the more the OEMs focus on making improvements for the official cycles. Hence the 1.6TDI VAG vehicles appearing to offer excellent mpg on paper, but in practice underwhelming.

[New POD]

In the words of Dave, a bloke I worked with in the 90's who had been a technician in the engine development part of Austin at Longbridge before he moved to Lucas, "They used to give the car magazines a car to do the 'road test' then they'd bring it back, and the next day they'd do some performance tests, and then they'd bring it back and the final day they'd do fuel consumption tests. Our job was to swap the engine over night. All the engines they tested were at one or other extremes of tolerance, so theoretically someone might get a car that refined, that fast, or that frugal, but never at the same time. I spent quite a bit of time measuring and selecting parts before assembly to get the right result"

Dave also came around in his Pj's and replaced all 4 ball joints on my Metro Turdo in under an hour.

And he 'tuned' my mini 850 so the MOT bloke threw the keys at me, telling me it was impossible for an A series to run so lean, so I'd past the emissions test and I could now put it back to normal. (It ran fine)

[paranoid airbag]

collateral said:

Emissions and mpg are two completely different things

http://en.wikipedia.org/wiki/Stoichiometry

There you go.

(Okay, no car burns all the hydrocarbon it puts in. Burning a lower percentage will give misleadingly low CO2 - but you could get the same power and CO2 AND better fuel economy from an engine which burns a greater percentage, and environmentalists would probably prefer you chucking CO2 out to chucking hydrocarbon out. The only good reason for not trying to design your engine to burn all the fuel it puts in I'm aware of is to stop knocking)

In related news: bears st in woods. Treating things more seriously, if legislators are genuinely suprised that manufacturers are doing this... it's very worrying for, well, everyone.

Edited by paranoid airbag on Thursday 14th March 22:24

[collateral]

Scuffers said:

davepoth said:

collateral said:

Emissions and mpg are two completely different things

No they aren't. The emissions figures are calculated from the MPG figures.

Actually it's the other way round...

Emissions test is from tailpipe emissions, MPG and CO2 are calculated from that.

Hrm. Either way, it seems like their tests don't give an accurate prediction of real world performance, so the testing methods are flawed

[Scuffers]

collateral said:

Scuffers said:

davepoth said:

collateral said:

Emissions and mpg are two completely different things

No they aren't. The emissions figures are calculated from the MPG figures.

Actually it's the other way round...

Emissions test is from tailpipe emissions, MPG and CO2 are calculated from that.

Hrm. Either way, it seems like their tests don't give an accurate prediction of real world performance, so the testing methods are flawed

Define real world?

The test was a compromise, as all tests are, at the time, they were reasonably valid, the problems started when governments started using the CO2 output for taxation, thus starting the manufacturers calibrating their cars to the test, and as soon as this happened, what we have now is inevitable.

If you must blame somebody, blame the EU governments.