According to on-road research conducted by the German automobile club ADAC, some diesel cars emit almost no NOx, suggesting the latest models are as clean as their petrol counterparts.
Tougher Real Driving Emissions 2 (RDE2) rules will be introduced in January 2020, requiring all new models launched to achieve 80mg/km or less (60mg/km for petrol). This will be a part of Euro 6d.
A tolerance (conformity factor) for the on-road test will be allowed, meaning the actual limit is 114mg/km for diesels and 86mg/km for petrols – significantly higher than any of the vehicles tested by ADAC. However, in January 2021 all cars sold must achieve more accurate figures. These tolerances will be removed by 2023.
The current RDE rules require diesel cars to emit no more than 168mg/km of Nox. (See below for full test results)
ADAC performed the tests using a portable emissions measurement device (PEMS), in the same way as the official test.