Real Driving Emissions – How REAL is it?

With the recent Volkswagen scandal focussing the world’s attention on the air quality problems associated with diesel cars, campaigners for clean air have expressed dismay over the EU’s decision not to impose stricter rules for testing new cars on the road. However, Emissions Analytics data shows that full compliance with the Euro 6 limits on oxides of nitrogen (NOx) is already being achieved by some vehicles, and thinks that the industry is on course to clean up dirty diesels.

What is interesting to note from the graph below is that of the 400+ vehicles tested by Emissions Analytics, only one Euro 5 car met the Euro 5 NOx limit, whereas four Euro 6 vehicles have already met the more challenging 0.08g/km Euro 6 regulation. The spread of NOx levels has also reduced in absolute terms with Euro 6, although proportionately the spread is similar to the Euro 5s before them. It is also abundantly clear that the majority of cars we have tested have failed to meet the regulations in real-world driving, with the average NOx levels four times more than they were certified as emitting. oct 15 rde The introduction of a Real Driving Emissions test (RDE) is set to reduce this divergence between laboratory results and real-world driving. Yet the announcement of the Conformity Factors last week, which set the levels of NOx vehicles are permitted to achieve during RDE, have been criticised by many as being too lenient. Our data shows that 36% of Euro 6 diesels have already met the 0.168g/km implied by the 0.08g/km limit plus the Conformity Factor of 2.1 that will come in from 2017 onwards and apply until 2020/1. However, taking into account the test-to-test variability with portable testing, which the Joint Research Centre of the EU recently estimated at up to 30%, manufacturers will need aim for emissions below the 0.168g/km to avoid being caught out during the RDE test. Using that variability number would suggest manufacturers will need to target 0.129g/km. This means that the 0.08g/km limit will be exceeded by around 60% on average in real-world driving. Of the Euro 6 diesels we have tested, 29% already meet this limit, as well as all gasoline cars.

Finally, all models will not need to comply until September 2019, and therefore we conclude that the new regulations as currently proposed will prove easier to achieve than might have been expected, even though some manufacturers and models have a greater task than others. As ever, we will be monitoring the situation and will report back with an update soon.