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From NEDC to WLTP: effect on the type-approval CO2 emissions of light-duty vehicles

The present report summarises the work carried out by the European Commission's Joint Research Centre to estimate the impact of the introduction of the new type approval procedure, the Worldwide Light duty vehicle Test Procedure (WLTP), on the European car fleet CO2 emissions. To this aim, a new method for the calculation of the European light duty vehicle fleet CO2 emissions, combining simulation at individual vehicle level with fleet composition data is adopted. The method builds on the work carried out in the development of CO2MPAS, the tool developed by the Joint Research Centre to allow the implementation of European Regulations 1152 and 1153/2017 (which set the conditions to amend the European CO2 targets for passenger cars and light commercial vehicles due to the introduction of the WLTP in the European vehicle type-approval process). Results show an average WLTP to NEDC CO2 emissions ratio in the range 1.1-1.4 depending on the powertrain and on the NEDC CO2 emissions. In particular the ratio tends to be higher for vehicles with lower NEDC CO2 emissions in all powertrains, the only exception being with the plug-in hybrid electric vehicles (PHEVs). In this case, indeed, the WLTP to NEDC CO2 emissions ratio quickly decreases to values that can be also lower than 1 as the electric range of the vehicle increases.
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