[m@rk]

BBC News - 'Carmakers manipulate emissions tests'

Didn't we already know this?

The book of tricks available to carmakers during the tests includes techniques such as:

> disconnecting the alternator, thus no energy is used to recharge the battery during the test

> the use of special lubricants that are not used in production cars, in order to reduce friction

> turning off all electrical gadgets such as the air-conditioning or the radio

> Slick tyres are pumped hard to reduce rolling resistance.

> Brakes are adjusted, or at times even disconnected, to reduce friction.

> Cracks between body panels and windows are taped up to reduce air resistance.

> Sometimes they even remove the wing mirrors.

[creepy coupe]

Originally Posted by m@rk

BBC News - 'Carmakers manipulate emissions tests'

Didn't we already know this?

Mercedes must have done all of those with the Wife's SLK. As it's nowhere near what they claim.

[djgandy]

No shit Sherlock.

[scooba0010]

My old Merc was 20% heavier on fuel than all there tests

[briers]

Seems so many people buy cars for economy, sad but now its turned into a pissing contest.

Cars claim 60, 70 or even 80mpg but in reality I've not driven anything that produces anything like this on average. My mrs bought a hybrid home from work once. I took it to Alton towers, the dullest drive I've ever undertook. I really tried for mpg, thought I might as well the cvt was hideous. Best I got was 53mpg average there and back and it was 70% a road. This was a new toyota hybrid thing too.

I can only think that small 1 litre superminis or small hybrids are only capable of getting higher than 50mpg consistently on the average tank.

The higher up the mpg ladder the more inaccurate the actual readings seem to differ from claimed.

Seems to me the bigger the engine the closer the actual mpg is to the claimed. My xfr does 19-20mpg average, official 21mpg and my 335d does 36-38mpg which I think is bang on claimed.

Only time this falls down is when you nail it everywhere which is most of the time. Even then the xfr only falls a couple of mpg, same with my 335d.

[verysideways]

A mate of mine has a 2 year old Astra 1.3 turbo diesel.
At 60mph it does better than 72mpg, but in normal every day use it averages out in the mid 50's.

Surprisingly sprightly for a 1.3 diesel in what is actually a reasonably spacious 5 door hatchback.

[mowflow]

I thought the official figures were obtained by running a car on a rolling road. No point taping up panels joints and removing wing mirrors then.

[LexS]

mowflow is correct, the NEDC test takes places on a rolling road so air resistance tricks aren't a factor.

The hybrids figures are the most misguided yet completely legitimate as running in electric mode is rated at 300mpg, so a plug in hybrid with a large cell and powerful motor can do the majority of the test in EV mode giving a largely exaggerated mpg figure from the test. Great for road tax, not so much if you do journeys greater than the range of the battery.

The alternator disconnection seems largely pointless as you can reasonable calibrate a battery management system not to charge unless on overrun and if starting the test with a high state of charge, which you will, charging won't be required much if at all until later in the test provided the auxiliary drains are kept to a minimum.

Yes, its a con to the public if you ask me, but the manufacturers are just doing what they can with the EU rules dealt.

[IanS100]

I don't think many people believe they'll ever achieve manufacturers mpg figures & provided they're all manipulating the figures, comparisons between vehicles will still be valid.

[doughboy]

Yes its rolling road test, so air resistance has nothing to do with it.

It's all fiddle factors, the test naturally favours smaller diesel engines as their characteristics suit the pattern. So fiddling suits some engines more than others, so its not a level playground.

As the test pattern hasn't changed for years, manufacturers have gotten better at fiddling the test more so than they have got better at actually reducing fuel consumption.

Especially in recent years as improvements become harder and harder to squeeze out.

All these tiny turbo petrol engines are the newest craze, very efficient on the test at light load, but give them some beans and its goodbye economy.


And yes the hybrid test is a FARCE as they start the test with a fully charged battery, but the energy used for that is not considered in the test - WTF!!!

[djgandy]

Originally Posted by doughboy

All these tiny turbo petrol engines are the newest craze, very efficient on the test at light load, but give them some beans and its goodbye economy.

This is why I just do not understand the tests at all. With no air resistance it is completely pointless! It's not even a test, merely a proof that a car will turn wheels.

These tiny engined "super efficient" cars are generally quite poor when they have to do 80 on the motorway. I think this is a big problem with these emission tests. It means people are making their cars to pass the test and get the stamp rather than performing well in reality and being fuel efficient.

Every time I drove the old 116i I couldn't help but think that if it did 10-20% less RPM's on the motorway it would be that little bit better at fuel. Of course I realised that 6th gear was there to pass the 50mph test with flying colours rather than improve fuel economy in the real world.

[IanS100]

Originally Posted by djgandy

Every time I drove the old 116i I couldn't help but think that if it did 10-20% less RPM's on the motorway it would be that little bit better at fuel. Of course I realised that 6th gear was there to pass the 50mph test with flying colours rather than improve fuel economy in the real world.

Donkey's years ago my other half had a Nissan Micra which claimed up to 67 mpg (IIRC). I don't doubt it did make that on a rolling road but on the open the road the gearing was a joke, it was so high that even the slightest gradient forced a change down to 4th to maintain speed and hills on the M62 were often taken in 3rd.

[doughboy]

Originally Posted by djgandy

This is why I just do not understand the tests at all. With no air resistance it is completely pointless! It's not even a test, merely a proof that a car will turn wheels..

The rolling roads are 'loaded' to simulate air drag, presumably related to the drag coefficient of each car, but the test has no gradients and no more than the most gentle of acceleration.

So a modern auto that can shuffle into 8th gear by 30mph does very well, but in reality the slighest hill would drop that back to 4th or 5th.

Picture below is the fixed Euro test cycle. First 800 seconds are the Urban test, and last 400 seconds are the extra urban test - thats it - 20 minutes of gentle driving, several minutes of which are stationary, so the benefits of stop-start are obvious here.

Speeds in km/h btw.

The regulations even state that "The test is to be conducted with all ancillary loads turned off (Air conditioning compressor and fan, interior and exterior lights, heated windows, seats, etc.)"

And also of note on Wiki "In one particular instance, research from two German technology institutes found that for diesel cars no 'real' reductions have been achieved after 13 years of stricter standards" i.e. the only improvement in the test cycle results were acheived by manipulation

[SteveC]

The more they manipulate the better.....given that all your road and company car taxes are based on that value