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| Worldwide Harmonized Light Vehicles Test Procedure | |
|---|---|
| Name | Worldwide Harmonized Light Vehicles Test Procedure |
| Acronym | WLTP |
| Developed by | United Nations Economic Commission for Europe |
| First adopted | 2016 |
| Purpose | Harmonize light-duty vehicle emissions and fuel-consumption testing |
| Status | In force in many jurisdictions |
Worldwide Harmonized Light Vehicles Test Procedure
The Worldwide Harmonized Light Vehicles Test Procedure is an international laboratory testing protocol for measuring vehicle emissions and fuel economy of light-duty vehicles, developed to replace older cycles such as the New European Driving Cycle and to provide consistent data for regulators, manufacturers, and consumers. It was created through technical work by bodies including the United Nations Economic Commission for Europe, the Working Party on Pollution and Energy, and specialist groups involving automobile manufacturers like Volkswagen Group, Toyota Motor Corporation, and Ford Motor Company. The procedure influences standards set by jurisdictions such as the European Union, Japan, and the United States Environmental Protection Agency.
WLTP specifies uniform laboratory conditions, instrumentation, and driving schedules to simulate realistic on-road operation for light-duty vehicles, harmonizing methodologies used across regions such as the European Union, Japan Automobile Manufacturers Association, and the International Organization of Motor Vehicle Manufacturers. It refines prior approaches exemplified by the New European Driving Cycle and complements roadside and real-world testing programs like the Real Driving Emissions protocol and Portable Emissions Measurement System campaigns. Stakeholders include regulatory agencies such as the European Commission, testing laboratories like those accredited by International Organization for Standardization, and automotive engineering groups at companies such as Daimler AG.
Development traces to cooperative work in the United Nations Economic Commission for Europe framework, with technical inputs from members of the World Forum for Harmonization of Vehicle Regulations and expert teams from Korean Automobile Manufacturers Association and the Society of Motor Manufacturers and Traders. Key milestones include drafting by working groups such as the Working Party 29 and endorsement by regional regulators including the European Commission and the Ministry of Land, Infrastructure, Transport and Tourism of Japan. Influential events in adoption included negotiations at meetings attended by representatives from International Energy Agency, Organisation for Economic Co-operation and Development, and national laboratories such as National Renewable Energy Laboratory.
WLTP defines dynamic driving cycles, chassis dynamometer settings, and conditioning procedures, replacing steady-state and low-dynamic cycles used under standards like the New European Driving Cycle and US Federal Test Procedure (FTP-75). Test sequences include the WLTP global drive cycle and subcycles derived for vehicle classes recognized by bodies such as the European Commission and the United Nations Economic Commission for Europe. Instrumentation requirements reference calibration protocols used by laboratories certified under International Laboratory Accreditation Cooperation and methods aligned with the International Organization for Standardization standards for emissions measurement.
WLTP covers passenger cars and light commercial vehicles as classified by regulatory frameworks including the European Commission Regulation No. 2017/1151 and classification schemes used by the United Nations Economic Commission for Europe. The procedure differentiates vehicles by mass and power-to-weight ratio, which affects test parameters for manufacturers such as Renault, Honda Motor Co., and General Motors. Exemptions and specific provisions have been negotiated with industry groups like the European Automobile Manufacturers Association and national ministries such as the Ministry of Environment (Japan).
The protocol prescribes measurement of regulated pollutants including carbon monoxide, nitrogen oxides, particulate matter, and carbon dioxide along with fuel and energy consumption for petrol, diesel, hybrid, and electric drivetrains. Test procedures incorporate conditioning of particulate filters and battery state-of-charge protocols relevant to manufacturers like BMW Group and Tesla, Inc. Measurement equipment and calibration traceability reference standards maintained by laboratories such as VTT Technical Research Centre of Finland and institutions participating in round-robin studies like Joint Research Centre (European Commission).
Adoption routes varied: the European Union implemented WLTP via legislative instruments and type-approval changes, while countries such as Japan and South Korea phased implementation through national ministries and testing agencies including Korean Agency for Technology and Standards. The procedure influenced labeling and taxation policies in jurisdictions like Germany and France and informed fleet reporting obligations administered by agencies such as the European Environment Agency and the United States Environmental Protection Agency. International coordination involved organizations including the Organisation for Economic Co-operation and Development and the International Energy Agency.
Critiques arise from manufacturers and research groups including studies at Imperial College London and testing organizations like Transport & Environment, citing increased complexity compared to the New European Driving Cycle, variability in laboratory-to-road correlation highlighted by Real Driving Emissions tests, and implementation costs reported by firms such as Stellantis and NIO Inc.. Limitations include sensitivity to test configuration choices documented by research at Chalmers University of Technology and concerns about harmonization efficacy between regions represented by actors like the United States Environmental Protection Agency and the European Commission.
Category:Automotive testing