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EU court rejects “excessively high” RDE NOx limits

14 December 2018

A European court ruled that the European Commission’s real driving emissions (RDE) NOx limit of 168 mg/km is illegal, and the provisions of the RDE regulation (2016/646) that set the NOx emission limit must be annulled. The decision was issued by the General Court of the European Union—a lower court of the European Court of Justice—in a legal case brought by the cities of Paris, Brussels and Madrid.

The RDE regulations introduced real driving emission testing requirements using portable emission measurement systems (PEMS), in addition to laboratory testing. The RDE NOx limit is defined as a product of the laboratory (NEDC) Euro 6 limit of 80 mg/km, and a conformity factor (CF). A CF of 2.1 became effective from September 2017 for type approval testing of new car models and from September 2019 for all vehicles (Euro 6d-TEMP). Hence, the effective RDE NOx limit is 80 mg/km × 2.1 = 168 mg/km. A CF of 1.5 becomes effective from January 2020 for new models and January 2021 for all vehicles (Euro 6d).

As the numerical value of the RDE limit is higher than the NEDC limit, the Court considered the Commission’s RDE regulation to represent an illegal relaxation of the Euro 6 regulation (715/2007). The Court concluded that the Commission had no power to amend “those limits for the RDE tests by applying correction coefficients”.

It may be noted that the Commission regulation—including the NOx conformity factors now annulled by the Court—was voted by the TCMV (EU’s Technical Committee—Motor Vehicles), and passed “regulatory scrutiny” by the European Parliament and the Council. The Commission’s original CF proposals in their working document for the TCMV meeting were 1.6 and 1.2, respectively.

This case is a clear example of the bad faith in the wake of VW Dieselgate scandal, and of the disconnect between engine and emission technology and the workings of the legal and political system. As engine emissions critically depend on operating conditions, emission limits can only be defined in the context of the test procedure. While the RDE NOx limit is numerically higher than the NEDC limit, it actually represents a much more stringent emission target—rather than a relaxation—because of the different testing procedure. To meet the RDE NOx emission requirements—along with other phased-in Euro 6 provisions such as OBD—carmakers had to upgrade vehicle’s SCR systems, and introduce SCR catalysts in diesel car models that didn't use SCR.

Under the Court decision, the NOx limit provisions of Regulation 2016/646 should be annulled, while other RDE provisions are not affected by the ruling. The annulled NOx limit will remain in place for the period of 12 months from the expiry of the 2-month appeal period, i.e., for 14 months from now.

The practical implications of the ruling are uncertain. The Commission has two months to appeal. If it does not appeal, it will have to amend the RDE regulation. If it does appeal, however, a final ruling may not be decided by the end of 2020. At that time, the Euro 6d CF of 1.5 may be already in place. The conformity factor of 1.5 is defined as 1 (i.e., the laboratory NOx limit) plus a margin of 0.5 that represents the uncertainty/error of PEMS instruments, to be reduced if PEMS technology is improved.

Source: General Court of the European Union