The development of the World-wide Harmonized Test Procedure for Light Duty Vehicles (WLTP) and the pathway for its implementation into the EU legislation

In order to assess vehicle performances in terms of criteria compounds, CO2 emissions and fuel/energy consumption, laboratory tests are mainly carried out. During these tests a vehicle is driven on a chassis dynamometer (which simulates the resistances the vehicle encounters during its motion) to follow a predefined test-cycle. In addition, all the conditions to run a test must strictly adhere to a predefined test-procedure. This is necessary to ensure that all the tests are carried out in a comparable way, following the requirement set by the relevant legislation. Test results are indeed used to assess the vehicle compliance with respect to, e.g., emission limits or to evaluate the fuel consumption that will be communicated to the customers. Any region in the world follows its own approach to carry out these types of tests. This has a series of drawbacks for both vehicle manufacturers and regulating authorities, leading in any case to a plethora of different conditions and results. In order to make a step towards the harmonization of the different test-procedures, the United Nations Economic Commission for Europe (UNECE) in 2009 launched a project for the development of a World-wide harmonized Light duty Test Procedure (WLTP), including also a new test cycle. Objective of the present paper is to provide a brief description of the WLTP and to outline the possible pathway for its introduction in the European Legislation.