Well whoop-i-do, official fuel performance tests do not match those in the real world. I think we always knew that. Now it has been discovered that VWs diesel tests in the US were as much as four times better than the proper result we must ask a relevant question perhaps. Are VW engines much worse than all the others, or have a large number of other engines been cheating, all over the world? It appears that VW engine management systems are employed in a large proportion of other manufacturers. Are these as a group better in performance also? Is the software in their cars also cheating, all over the world perhaps?

This could just be the start of it they say on the news.

They were saying on the news the American test measures different chemicals via emissions test, and its stricter than our UK emissions test.

I can see others falling foul.

It was discovered because a pressure group in the States was trying to convince European authorities that diesels could be as clean as petrol because VW tests in USA showed this. The question really is "how many of our cars are cheating?"
It's all a fraud, tests in UK are carried out by the manufacturers representative group, the results bear no relationship to actuality and yet it has suited all to continue that practice, except the end user.
In the 1950s most family cars did around 30-35 mpg. It's not much better now (although cars are faster and more powerful than then, average journey times are very similar). The question should by "why has no one taken action before?"

Still don't get this, all cars are designed to meet the emission test standards in the different countries - VW's clearly did!

It there is a problem then the tests themselves were lacking and I don't see how VW can be blamed for that.

How does the car detect it is being tested, I can think of lots of ways (air flow, motion, steering inactive, loading etc) but all lead to the test not being realistic. If you want to test for normal deriving then you stick the probe up the exhaust and go for a drive.

The one and only really sneaky cheat that I can think of is using the car's GPS to identify you are at a testing centre.

This is like being breathalysed and passing but then being prosecuted because you cheated by not having a drink - you passed the test but are still guilty???

I think you have to disable the airbags for fear that someone bumping into it on test, or slamming a door whilst its on the test bed will trigger them.

I think there are other things that have to be disabled too.

M'learned friends will argue about it for years, but the real damage is to the reputation of VW and the damage to its sales.

I remember the airbag trick from some years ago, doing a bit of digging I found ...



If the test doesn't bother doing a road test as well then I would say the test is lacking.

VW aren't going to be the only one that are doing similar, I bet VW are busy testing other marques of cars at this moment in time.

The fiddle was written into the cars software it knows when the hardware is connected for any test or investigation. It would have to be written in with the sole intention to deceive, by programmers with instructions to do so.

The car software test wheel rotation. When it detect two wheels not turning ant-skid software kicks in, It is that signal which is used to initiate the anti-pollution cheat.
Don't know how it copes with four wheel drive though!
Got this from the Times

All said an done,we have come a long way with diesels with clever injectors that are capable of injecting upto 6 times per cycle burning all the fuel in a controlled burn instead of dumping the lot in one go making loads of noise an dumping unburnt fuel out the exhaust,remember the cans of easy start we use to go through

'So what are the garages doing during mot testing.are they working to a different standard . i had a car fail mot on emissions..had to squirt some stuff up the carb to get it to pass.

In America most States have an Annual Safety and Emissions Test.

Our MOT doesn't test the emissions to the same levels as the Type Approval that manufacturers have to adhere to. The MOT is primarily a safety test but basic environmental tests are also performed. In petrol cars the emissions are only tested at idle for the MOT.

I had a DPF filter that kept on being choked up. The garage couldn't find the cause and mentioned teh possibility of simply removing the DPF. I refused to do this and the fault was found to be a split hose and cured. It was also explained to me that the car would still pass it's MOT emission test, even without the DPF. Suspicious or not?

Since then, I have noticed a number of cars like mine emitting a cloud of smoke on accelerating. I assume this is because they have no DPF, having had it removed.

I think spot testing should be used to check emissions, with heavy fines for this practice.

This is a different test than the economy test right?
Seems like people are mixing the 2 up.
A bigger concern for people is the blatantly false mpg figures. The US have a different system for rating this and seem much more closely matched to real world miles achieved.

In the UK, the emissions test for a diesel car is a plain smoke test. A probe is inserted up the exhaust, and the engine is revved - the smoke level in the gasses are then measured.

The diesel smoke test is the same for every diesel car, no matter if its 30 years old or 3 years old - the same smoke limit applies.

Newer cars with DPF's fitted produce virtually zero smoke, but older cars without produce more, there is no cut off year where the smoke level should be lower.

In a petrol car, you have a CAT test. Everything post 1993 (IIRC) needs to pass a cat test, which is much tigher than that on a car without a CAT fitted (pre 1993). On a diesel there is no cut off year, so all diesels are tested to the same limits.

Emission wise, a poorly running new car which should produce no smoke, can pass a the test producing as much smoke as a dirtier 30 year old car. Although modern diesels have become cleaner, the MOT test (unlike that for petrol cars) hasnt evolved.

Diesels first used before 1979 have a visual smoke check, after 1979 they are measured and visual.

If a diesel first used after 1979 doesn't pass the fast check, then it has do do the detailed check which has different limits depending if it is turbo or non-turbo and whether it was first used before or after 2008.

So basically there are three year dependent measurements, pre 1979, 1979-2008 and 2008 onwards, the 2008 onwards being the strictest.

I like "Zero smoke", but "virtually' is just a joke. I followed a fairly new black Merc up Leasowe Road last week. Each time it accelerated huge clouds of black smoke were emitted, and I mean huge, it was almost impossible to see through them. He eventually turned right in to Box Lane, again with huge clouds of smoke. I just hope he was going to a garage for repairs! Otherwise he should be off the road.
By the way is it true that some diesels are programmed to pump raw fuel into their exhausts in order to burn their Cats clean. If true I bet they don't do it on emissions tests!

Some cars have an active DPF regeneration cycle which puts extra fuel into the engine so that it is burnt in the exhaust and increases the DPF temperature to burn off accumulated muck, this is an accepted method and testing wouldn't be performed while the car is doing a regeneration cycle.

Diesel should have regular higher rev driving (3000rpm or above) for at least 10 mins every week or two to keep the DPF and exhaust system relatively clean, this will generally reduce the need for the car to go into a regeneration cycle.

What happens if my VW has emissions cheating software : Click Me

Hypothetical question. What will owners say when their cars have had their software altered to lower the NOX levels and then find out how much the engine power has been reduced?

It shouldn't significantly change the engine power on the road.