6 Other Emissions & On-road
Since September 2014 the Euro 6 emission limit has applied for new-vehicle type approvals, and since September 2015 it has been mandatory for all new vehicle sales. In 2017, more than 95 % of all new registrations were Euro 6 vehicles (Fig. 6-1).
The progression from Euro 3 to Euro 6 resulted in significantly lower emission limits. Emissions, as measured over the NEDC test cycle, are generally in compliance with these limits. However, on-road measured nitrogen oxide (NOx) emissions have not decreased to the same extent. Over the ensuing three years, a number of government agencies across Europe began to systematically test diesel cars for their emission levels. On average, for 541 diesel cars tested by, among others, the German, French and UK governments, the average conformity factor for Euro 5 vehicles was 4.1 and for Euro 6 vehicles 4.5. The difference between individual vehicle models is particularly remarkable, with some Euro 6 diesel cars emitting less NOx than the limit while others exceed the regulatory limit by a factor of 12. Only 10% of tested Euro 6 vehicles would meet the Euro 6 limits on the road (Baldino et al., 2017).
For fuel consumption and CO2, a similar pattern is seen, with a discrepancy between laboratory and on-road fuel consumption of around 40 % (Tietge et al., 2018). An analysis of the underlying reasons for the growing gap suggests that increasing exploitation of tolerances and flexibilities in laboratory testing is the main driver of this development (Stewart et al., 2015).