European Commission study envisages emissions figures increasing 19% with WLTP

25 May 2017

According to a scientific study carried out on behalf of the Joint Research Centre (JRC) of the European Commission, the change in the vehicle testing regime from NEDC (New European Driving Cycle) to WLTP (Worldwide Harmonised Light Vehicle Testing Procedure) will lead to a wide-ranging increase in emissions figures.

From September, the NEDC regulation, which is the current system for measuring fuel consumption for vehicle homologation will be phased out with the WLTP gradually coming into force and being mandatory for all from September 2018.

The fact that the change in the method of measuring vehicle fuel consumption will naturally alter CO2 emissions figures is widely known. However, according to a scientific study published on 11 May, the change in the testing system will result in an ′average ratio’ of 1.19, ′representing a delta between WLTP and NEDC of 23.1g CO₂/km,’ according to the study’s authors. This is in line with German trade journal Kfz-Betrieb, which reported in March that: ′Initial investigations have shown that an average increase in emissions is expected to be 20 percent.’

The scientists do not consider this to be an absolute rule, however. According to their studies and many others, ′the data show that there is clearly a decline in the ratio between the two measurement modes from the moment when the CO₂ values ″‹″‹expressed in NEDC increase.’

In fact, the authors have identified a ′threshold’ of 250g CO₂/km. From this emission level, ′the ratio becomes less than 1, which means that the WLTP values ″‹″‹should be lower than those expressed in NEDC for vehicles above the threshold.’ The authors have also indicated that the upward reassessment of CO₂ emissions will be greater for petrol-powered vehicles than those powered by diesel.

In Germany, the Federal Government has already introduced a draft bill which amends the Motor Vehicle Tax Law, whereby the new WLTP cycle will serve as the basis for the measurement of carbon dioxide emissions from September 2018 onwards. OEMs anticipate tax rises as a result but the German Association of International Motor Vehicle Manufacturers (VDIK) asserted late in March that the change in the car tax calculations cannot malign new vehicles. Klaus Bräuning, managing director of the VDA, the German automotive industry association, told the Frankfurter Allgemeine Zeitung: ′It is not possible to explain why car buyers should pay significantly more taxes for a vehicle that has not been technically altered and thus does not have a worse environmental record.’ Based on a 20% increase in carbon dioxide emissions figures, motor vehicle tax revenues in Germany are set to increase by €435 million per annum.

In the UK, the Government is expected to adapt the new VED regime which was introduced on 1 April to the new WLTP CO₂ figures from January 2019. Instead of adopting a complex approach in the meantime, one solution could be the use of a simple conversion of NEDC figures to WLTP figures from September 2017 to January 2019. However, this merely remains a possibility. The VDA states that ′the achievement of the targets in the WLTP cycle requires different engineering measures from those required for the NEDC.’