Car industry applied limit values for NOx emissions in laboratory only
The representative of Volkswagen made very clear, just like the Renault representative before him, that the industry interpretation of the Euro 5/6 regulation is that the limit values for NOx emissions only have to be met during the type approval test in the laboratory. Several Members of the inquiry committee stressed that the regulation actually requires the limit values to be met under normal driving conditions (Article 5.1). When explaining what VW did wrong and what is now being fixed while 9 Million cars are called back in the EU, Ulrich Eichhorn admitted software had been used which recognised when the car was driving in the test cycle. He claimed that this was necessary, as certain features would have to be deactivated during the test cycle. The mistake was however to link the functioning of the emissions control to this test cycle recognition and switch to a different mode when driving outside the test cycle. This however would not constitute a defeat device. Also this interpretation of what a defeat device is was quite puzzling for the audience.
The main fix for the concerned cars is to remove this link between test cycle recognition and exhaust control. This fix however only reduces the emissions under normal use e.g. of a Euro 5 Passat to approximately 550 mg/km which is well above the limit value of 180 mg/km and 3,7 times the value measured in the laboratory. The VW representative failed to properly explain this discrepancy and claimed that no thermal window was used. He stated that the exhaust circulation needed to be reduced to ensure durability of the exhaust control and full performance of the car. How this is achieved without a defeat device and why he thought that this modification of the functioning of the exhaust control outside the test cycle was legal under the EU regulation remained unexplained.
It seems that manufacturers were very comfortable in assuming that the laboratory test was the only situation in which the limit values have to be met and that the level of emissions on the street were completely irrelevant. This of course completely fails to recognise the explicitly stated aim of the regulation which is to improve air quality and public health. Strangely also no public authority seems to have intervened to rectify this misconception of the industry.