<i>Its not clear this is any kind of problem. Reducing emissions in lab tests may very well result in car designs that have reduced road emissions.</i><p>This is the logic that European politicians have used in the past.<p>If there were a direct relationship between lab test emissions and real-world emissions, that approach may be acceptable. Unfortunately, that is not the case.<p>In the case of NOx, implementing the Euro standards <i>should</i> have resulted in an 80% reduction in emissions over the past 15 years. As the vehicle fleet is renewed, that <i>should</i> have translated into significant reductions in kerbside NOx levels. But this has not happened, and London continues to suffer some of the worst NOx levels in the world.<p>It turns out that an 80% reduction in lab test emissions has not translated into anything like an 80% reduction in real-world emissions - not even close!<p>The current system is inadequate because manufacturers simply &quot;design for the test&quot;. There is huge real-world variability between vehicles that may record very similar lab test scores. A vehicle may claim similar test score results as another, but in fact have hugely differing levels of emissions in the real world.<p>Test environments need to reflect real-world conditions!