Since September 1st 2017, certain new vehicles were already type-approved using the Worldwide Harmonized Light Vehicle Test Procedure (WLTP), which is a new, more realistic test procedure for measuring fuel consumption and CO2 emissions. For passenger cars from September 1st 2018 the WLTP fully replaced the New European Drive Cycle (NEDC), which was the former test procedure.
The driving cycle of the WLTP ("Worldwide Harmonized Light Vehicle Test Procedure") addresses key criticisms of the NEDC ("New European Driving Cycle"). In particular, the new WLTP driving cycle driving profile corresponds more closely to nowadays everyday operation, and it is not just measured for a base vehicle, but also takes into account the influence of additional optional equipment.
Due to more realistic test conditions, the fuel consumption and CO2 emissions measured under WLTP are in many cases higher compared to those measured under NEDC. The daily fuel consumption of a vehicle depends very much on the individual usage profile and where and how it is being driven: city traffic, country roads or motorways. These differences are better accounted for by the WLTP driving cycle. Instead of calculating only the values "urban, extra-urban and combined" (as stipulated by Regulations (EC) No. 715/2007 and 692/2008,) on the basis of a more theoretical driving profile, WLTP provides four individual values for different predetermined travel profiles (low, medium, high, and extra-high) that are based on statistical surveys and the analysis of user profiles and averages. In addition, the WLTP driving cycle is much more dynamic than the NEDC and reflects higher accelerations, a higher average speed and a higher maximum speed.
However it is still legally required to publish fuel consumption and emission values according to NEDC. These values are backcalculations from the measured values according to WLTP.