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Control of Pollutant Emissions

State of diesel vehicle emissions

A large panel of diesel cars was tested on chassis dynamometers and on the track, under the control of an independent commission,

with the aim in particular of detecting anomalies in pollutant treatment devices. 

The Independent Commission

The Ministry of the Environment has set up an independent commission to analyse the results of tests entrusted to UTAC and make recommendations. This commission brought together consumer associations, departments of the ministries of ecology, industry and the economy, ADEME, and scientific experts.

The Test Protocol

In January 2016, the independent commission responsible for evaluating vehicle emissions validated the specifications so that the 100 scheduled vehicles could be tested by UTAC. The objective of the test protocol is to detect a possible decoy anti-pollution system and to verify compliance with the certification requirements, using discriminating tests, comparing emission measurements on a bench and in a real driving situation, over cycles identical tests in terms of vehicle stress. Each car undergoes 3 tests. For each of these tests, the parameters are different from those of the certification test (speed, temperature, preparation of the car, etc.).

The Final Report of the Independent Commission

At the end of a 10-month campaign, 86 vehicles were tested and their results analysed by the independent commission. The independent commission also heard several manufacturers in order to give the possibility of a contradictory as well as a federation of equipment manufacturers. The Ministry of the Environment published the report of the independent commission on July 29, 2016: the results of the work were fruitful, and 13 recommendations were proposed. The Ministry has undertaken actions in this direction with the aim of strengthening the real reduction of vehicle emissions, and the transparency, and efficiency of the vehicle instruction and control processes.

The tests carried out did not make it possible to establish the presence of a device making it possible to deceive the homologation cycles or to exclude such a possibility. These tests nevertheless showed significant overruns of the emission limits in real traffic conditions. They revealed that the pollution control systems used by several manufacturers did not operate optimally at all times in order, according to the manufacturers questioned, to preserve various engine components. 

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The Independent Commission had no Judicial Power

The tests were carried out with the information available. The French investigation and those of the German and English authorities in particular have contributed to bringing together numerous measurements made under rigorous and reproducible conditions. Following the meeting of the independent commission on September 22, 2016, the Ministry decided to pursue additional investigations in a targeted manner in order to better understand the malfunctions of the processing devices. These analyses were entrusted to IFPEN. A public report was also released 

The action of the Ministry of the Environment did not stop at the report of the independent commission. The Ministry of the Environment has required national manufacturers to set up action plans to improve the performance of pollutant treatment devices. The ministry is closely monitoring the implementation of the improvements announced in particular by the Renault manufacturer to the independent commission.

Revision of the Certification Framework

On January 27, 2016, the European Commission published a draft regulation aimed at replacing the framework directive 2007/46/EC on the approval of motor vehicles, their trailers and systems, components, and separate technical units intended for these vehicles. The aim was, on the one hand, to reduce the differences in interpretation of the current regulatory framework and, on the other hand, to improve it in the light of lessons learned from the case relating to the presence of devices for invalidating the treatment of pollutant

The conclusions of the fitness check carried out in 2013 on the current framework directive on vehicle type approval (2007/46); and commitments made by the Commission in its CARS 2020 action plan to promote a strong, competitive, and sustainable European automotive industry.



From the start of the discussions, the French authorities supported an ambitious overhaul of this directive, which was to correct the weaknesses of the current system. In particular, they wanted the new regulation to improve the transparency, independence, quality, and efficiency of the approval system. In particular, they asked for the creation of an independent European authority but without success.

Regulation (EU) 2018/858 of the European Parliament and of the Council

It provides in particular for an increase in the level of quality and independence of type-approval and testing of a vehicle before it is placed on the market, by clarifying the roles and responsibilities of all the players in the economic chain and strengthening market surveillance vehicles and parts. 

Test protocol – the new test cycle on chassis dynamometer “WLTP”

The light vehicles approved today are tested for pollution according to European and international regulations. The test consists of following a test cycle which represents a “scenario” made up of accelerations, decelerations, and stages at a constant speed over a period of 20 minutes. 

Until September 1, 2017, the cycle in force was the NEDC (New European Driving Cycle), developed almost 40 years ago (in force since July 1973). It has been replaced by the WLTP (Worldwide harmonized Light vehicles Test Procedure), designed worldwide as part of the work carried out under the aegis of the United Nations, in order to gain representativeness. 



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