In 2014 the United Nations Economic Commission for Europe (UNECE) adopted the global technical regulation No.15 concerning the Worldwide harmonized Light duty Test Procedure (WTLP) while the European Commission is now aiming at introducing the new test procedure in the European type-approval legislation in order to replace the New European Driving Cycle (NEDC) as the certification test. The current paper aims to assess the effect of WLTP introduction on the reported CO2 emissions from passenger cars presently measured under the NEDC and the corresponding test protocol. The most important differences between the two testing procedures, apart from the kinematic characteristics of the respective driving cycles, is the determination of the vehicle inertia and driving resistance, the gear shifting sequence, the soak and test temperature and the posttest charge balance correction applied to WLTP. In order to quantify and analyze the effect of these differences in the end value of CO2 emissions, WLTP and NEDC CO2 emission measurements were performed on 20 vehicles. WLTP CO2 values range from 125.5 to 217.9 g/km, NEDC values range from 105.4 to 213.2 g/km and the ?CO2 between WLTP and NEDC ranges from 4.7 to 29.2 g/km for the given vehicle sample.
Keywords: NEDC, WLTP, CO2, Fuel Consumption, European Regulation.