From NEDC to WLTP: Effect on the Energy Consumption, NEV Credits, and Subsidies Policies of PHEV in the Chinese Market

Abstract

The switching from new European driving cycle (NEDC) to worldwide harmonized light vehicles test procedure (WLTP) will affect the energy consumption of plug-in hybrid electric vehicle (PHEV), and then affect the new energy vehicle (NEV) credit regulation and subsidy policy for PHEVs. This paper reveals the impact on energy consumption, NEV credit regulation, and subsidy policy for PHEV in the Chinese market of the switching from NEDC to WLTP based on qualitative analysis and quantitative calculation. The results show that the WLTP procedure is stricter than NEDC in the determination of road load, test mass, driving resistance forces, and tire selection. Firstly, the electricity consumption (EC) of PHEV in charge-depleting mode (CD) under the WLTP procedure is 26% higher than NEDC on average, which makes the all-electric range (AER) significantly lower under WLTP. The weight EC tested in the WLTP procedure is higher than NEDC. Secondly, the fuel consumption (FC) of PHEV in CD mode is related to the adjustment of the engine management system (EMS) and the size of battery energy under the WLTP procedure. For the FC in the charge-sustaining (CS) mode of PHEV under the WLTP procedure is 20% higher than NEDC on average. However, the weight fuel consumption of PHEVs under WLTP with a long AER may be lower than that of NEDC due to the characteristics of utility factor in the WLTP procedure. Thirdly, most PHEVs fail to meet the requirements of 50 km AER due to the switching of the test procedures. However, the Chinese government reduced the technical specification of PHEV’s AER under the WLTP procedure to 43 km to support the development of PHEV technology. It ensures that the switching of test procedures does not change the treatment that they could obtain, the NEV credits, and subsidy as a NEV in China. However, the increasing of the EC in CD mode and the FC in CS mode under the WLTP procedure makes the PHEV obtain lower credit and subsidy multiple compared with NEDC procedure.