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https://en.wikipedia.org/wiki/Europe...sion_standards
Cycle beating
For the emission standards to deliver real emission reductions it is crucial to use a test cycle that reflects real-world driving style. It was discovered that engine manufacturers would engage in what was called 'cycle beating' to optimise emission performance to the test cycle, while emissions from typical driving conditions would be much higher than expected, undermining the standards and public health. In one particular instance, research from two German technology institutes found that for diesel cars no 'real' NOx reductions have been achieved after 13 years of stricter standards (2006 report).[19]
An independent study in 2014 used portable emission measurement systems to measure NOx emissions during real world driving from fifteen Euro 6 compliant diesel passenger cars. The results showed that NOx emissions were on average as much as 7 times higher than the Euro 6 limit. However, some of the vehicles did show reduced emissions, suggesting that real world NOx emission control is possible.[20]
In 2015, the Volkswagen common-rail TDI diesel engine emissions controversy involved revelations that Volkswagen AG had deliberately falsified emission reports by programming engine management unit firmware to detect test conditions, and change emissions controls when under test. The cars thus passed the test, but in real world conditions, emitted up to 40 times more nitrogen oxides than allowed by law.[21]
Upp till 40ggr MER kvvgaser