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WLTP cycle replaces NEDC

The NEDC cycle

The New European Driving Cycle (NEDC) was a driving cycle designed to represent typical driving conditions on European roads.
The NEDC test cycle was mainly used to measure fuel consumption and pollution from vehicle emissions by means of the test procedure covered within the scope of Directive 70/220/EEC, which set permissible emission limits for gasoline-fuelled and diesel-fuelled engines of passenger cars and light commercial vehicles. This directive was repealed by the Regulation (EC) No 715/2007 which introduced Euro 5 and Euro 6 emission standards.

The first European driving cycle referring to typical driving conditions in European cities was introduced in 1970. In 1992, the NEDC was updated to include an extra urban phase as well, and since 1997 it has been used for measuring fuel consumption and CO2 emissions.

Valid in the EEC, the NEDC test cycle expired in 2018 when it was replaced by the new WLTP test (Worldwide Harmonised Light Vehicles Test Procedure). The WLTP test simulates real driving conditions of a vehicle; however, it is still carried out in a laboratory. The WLTP testing cycle has been applied to new passenger cars since September 2017, and for all new vehicles since September 2018.

The WLTP test procedure

The WLTP procedure (Worldwide Harmonised Light Vehicles Test Procedure), is a global, harmonised certification standard for determining the levels of pollutants, CO2 emissions, fuel consumption and electrical autonomy of passenger and light commercial vehicles.

Set up by experts from the European Union, Japan and India, under the auspices of The World Forum for Harmonisation of Vehicle Regulations, which is a working party (“WP.29”) of the United Nations Economic Commission for Europe (UNECE), is also responsible for creating a uniform set of regulations to globally improve vehicle design.

Similarly, as within the NEDC test procedure, the WLTP cycle takes place in laboratories with vehicles being placed on a chassis dynamometer. In addition to EU countries, WLTP is used as the standard test in Switzerland, Norway, Iceland, India, Liechtenstein, Turkey, and Israel. Other countries that have signed the WLTP agreement include China, Japan, South Korea, Russia, India, and the United States, thus reducing the gaps that had existed so far between the different certification cycles.

The tests are conducted at a temperature of 14°C upon start up and then at 23°C. Testing conditions initially simulate colder weather. The coolant is thus not at its optimum temperature at the beginning of the test.

The WLTP simulates the real-life driving conditions more accurately. The WLTP includes more dynamic phases when compared to NEDC, the acceleration rates also better reflect real-world driving conditions. The average speed during WLTP testing is 46.5 km/h, compared to 34 km/h for NEDC testing, and the maximum speed for the former is 131.3 km/h compared to only 120 km/h for the latter.The cycle testing time goes up from 20 minutes for NEDC to 30 minutes for WLTP. Vehicles travel 23.25 km distance during the WLTP test, compared to 11 km for the NEDC. The WLTP test consists of four parts depending on the maximum speed: 

  • Low, up to 56.5 km/h
  • Medium, up to 76.6 km/h
  • High, up to 97.4 km/h
  • Very high, up to 131.3 km/h.

These parts of the new cycle simulate urban and suburban driving, and driving on extra urban roads and motorways. The procedure also considers all vehicles' optional features that may affect aerodynamics, rolling resistance and vehicle mass, resulting in a CO2 value that reflects the characteristics of a given vehicle. 

Because the WLTP is more specific, it reveals higher level of CO2 emissions (31%) than the NEDC (24%).

The WLTC certification test is carried out on production vehicles, an example being pre-series samples. For a vehicle to be “eligible” for testing, the distance shown on the odometer must be less than 80 km. These tests must be repeated at least every 3 years, as long as a given type of vehicle is produced. 

Remark: fuel used for testing is up to manufacturer’s decision.

Emissions testing is no longer conducted just in the lab, but also on the road according to the Euro 6d-TEMP standard and with the even more far-reaching Euro 6d standard. Lab measurements according to the WLTP are supplemented by the RDE test (Real Driving Emissions). Pollutant emissions (including nitrogen  oxides and particles) are measured in vehicles directly on the road and compliance of limits with conformity factors is checked.

The RDE (real driving emissions)

The Real Driving Emissions (RDE) test measures the pollutants, such as nitrogen oxides (NOx) emissions and fine particles (PM), emitted by cars in real drive conditions. RDE complements the WLTP laboratory test and is carried out according to random variations of parameters. In France, l'UTAC, mandated by Centre National de Réception des Véhicules ("National Vehicle Certification Centre”), is responsible for carrying out these tests.

In practice, it is a complementary test, under which a car is driven on public roads, in real situation. Cars are fitted with a portable emission measuring system and are driven for a maximum of 2 hours traveling up to 60 km/h in urban conditions; up to 90 km/h in rural conditions; and 145 km/h, in motorway conditions, at temperatures between - 7 ° C and 35 ° C, and at an altitude of up to 1300 m. 

Europe aims to reduce NOx emissions to 80 mg/km by 2023 for all vehicles, with an intermediate threshold of 168 mg/km in 2021. The collected data serve to verify whether the vehicle's nitrogen oxides emissions meet the RDE requirements.

Remark: the RDE test results are not included in the calculation of official emission rates. This test procedure checks the nitrogen oxides emissions (NOx) to reduce the discrepancy between emissions measured in real driving and those measured in a laboratory (WLTP).

Evaporative Emissions Test Procedure (EVAP)

Evaporative emissions from a vehicle can be defined, in a very generic way, as Volatile Organic Compounds (VOC) emitted by the vehicle itself under different operating conditions but not directly derived from the combustion process. Fuel-related evaporative emissions may occur during any vehicle operation including parking events, normal driving, and vehicle refuelling.

The evaporative emissions test procedure was developed in 2016 by the WLTP informal working group and enables measuring of the amount of evaporative emissions from petrol over a 48-hour period.

In-Service Conformity Test (ISC)

The In-Service Conformity Test includes the measurement of gaseous pollutants under laboratory and real-life driving conditions, as well as evaporation tests. The manufacturer guarantees vehicle compliance against type-approval data for at least five years or 100,000 km, whichever comes first.

French bonus-malus vehicle tax policy for new vehicles 

Following the implementation of the WLTP standards, the French government revised the malus vehicle tax system pursuant to Article 69 of the Financial Administration Act 2020.

  • Since 1 January 2020, the French government has been applying a maximum payable malus up to €20,000 for vehicles with CO2 emission levels up to 110 g/km.
  • Taking better account of the real-life driving emissions of vehicles, the system was converted to WLTP from 1 March 2020, with no impact on the amount of environmental taxes.
  • Another environmental tax policy review is planned for 1 January 2021 to merge different environmental taxes.

The ecological bonus is now allocated for purchase of electric or hydrogen-powered vehicles with CO2 emission levels up to 20 g/km. The total sum of bonus is reviewed annually and is subject to eligibility criteria.

European certificates of conformity and WLTP standards

For vehicles that are type approved on the WLTP starting from 1 September 2017, CO2 and fuel consumption data will be provided both in accordance with the new WLTP test procedure (point 49.4 on the Certificate of Conformity) as well as with the old NEDC test procedure (point 49.1 on the Certificate of Conformity). 

NEDC CO2 and fuel consumption values will continue to be indicated until 2020, inclusive within the Certificate of Conformity that a manufacturer issues when a new vehicle is placed on the market.