The globalisation of automotive exhaust emissions testing and measurement procedures has been in progress for a number of years and has already been introduced for vehicles such as motorcycles, on road heavy-duty vehicles (trucks/buses) and Non-Road Mobile Machinery (NRMM). The latest vehicle category for which a Global Technical Regulation (gtr) is to be developed in the Light Duty Vehicles. The paper reviews the history and current status of the Worldwide Harmonized Light Duty Vehicle Test Procedure (WLTP) program and the development of the new regulation for its world wide application. The document will also compare the draft WLTP requirements and procedures with those of the USA who have recently introduced their own draft procedures (CFR 1066) and highlight potential conflicts.