Since 1 September 2017, some new vehicles have undergone type approval in accordance with the Worldwide Harmonized Light Vehicles Test Procedure (WLTP). This puts the vehicles through a more realistic test procedure for the measurement of fuel consumption and CO₂ emissions. From 1 September 2018, the WLTP has replaced the New European Driving Cycle (NEDC) on a step-by-step basis. As a result of the testing procedure being more representative of real conditions, the fuel consumption and CO₂ emissions values achieved as part of the WLTP are, in some cases, higher than those of the previous NEDC procedure. In light of this, from 1 September 2018, appropriate changes may apply to vehicle taxation. At present, the NEDC values are still the values which must be communicated in line with legal requirements. In the case of new vehicles which are type approved in accordance with WLTP, the NEDC values are derived on the basis of the WLTP values. The additional disclosure of the WLTP values remains voluntary until such time as this is legally prescribed.