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UNECE adopts more accurate fuel efficiency and CO2 test for new cars (WLTP)

Published: 12 March 2014

When buying a new car, customers will have a better understanding of the fuel consumption of the vehicle thanks to a new standard testing method agreed to at the United Nations Economic Commission for Europe (UNECE) in Geneva.

The test cycle of the Worldwide Harmonized Light-duty Test Procedures (WLTP), adopted today as a first step by the World Forum for Harmonization of Vehicle Regulations (WP.29), will be used in the future for measuring, amongst others, the fuel consumption, and therefore the CO2 emissions, of passenger cars, vans and vehicles less than 3.5 tons. This test cycle is the result of five years of efforts at the World Forum at the request of policy makers, the industry and consumers.

The WLTP test cycle is a much more accurate testing method than the current system, known as the New European Driving Cycle (NEDC), used since 1996. WLTP better simulates real driving conditions, with more modern and realistic driving scenarios and considers other widely used factors such as air conditioning and seat heaters that drive fuel consumption upwards. It also closes many of the loopholes that existed in the current test method in order to create accurate, consistent and repeatable results on fuel consumption which are thus more difficult to manipulate. As a result, it is estimated that the figures of the fuel consumption under the WLTP would be 10 to 20% higher than those under the current test cycle.

Once Contracting Parties have transposed WLTP into their national or regional legislation, consumers buying cars will feel more secure that the fuel efficiency advertised by manufacturers will be more representative of real fuel consumption, and know that there will be no surprises at the service station.

In addition, with more accurate CO2 emissions measurements, governments will have confidence to determine carbon emission limits.

After the adoption of this UN Global Technical Regulation on WLTP, the Contracting Parties voting in favor will have one year to initiate introducing it into their national or regional law.

The text of the Global Technical Regulation is available at:

Note to editors


The World Forum for Harmonization of Vehicle Regulations (WP.29)  is a Working Party within the United Nations Economic Commission for Europe's Inland Transport Committee. It manages three Global Agreements on vehicles. Any country that is member of the United Nations may participate in the activities of the World Forum and accede to the Agreements.

1998 Global Agreement

The 1998 Global Agreement establishes a process through which countries from all regions of the world can jointly develop UN Global Technical Regulations (UN GTR) regarding the safety, environmental protection systems, energy sources theft prevention of wheeled vehicles, equipment and parts.

The 1998 Agreement entered into force on 25 August 2000. There are currently 15 UN GTRs established under this Agreement.


List of contracting Parties



South Africa




New Zealand










People’s Republic of China

Republic of Korea





European Union


Republic of Moldova

Russian Federation





United States of America




With WLTP, the test cycle ran by the type approval authority in a laboratory will be performed on a test bench with a running car, which is accelerated and decelerated according to a well-defined speed profile, allowing to measure not only the level of gaseous pollutants, but also of the CO2 emissions and, thus, the fuel consumption level.

CO2 emissions

CO2 emissions (in g/km) are directly linked to fuel consumption (FC in l/100 km) under the following formula.

Diesel engine: CO2 emissions value (g/km) ≈ 26.5 x FC (l/100km)

Gasoline engine: CO2 emissions value (g/km) ≈ 24 x FC (l/100km)

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