Wolfsburg, 01 November 2017
From NEDC to WLTP
Ten facts on the new exhaust emissions test
Complex installation: the mobile test equipment is prepared.
Complex installation: the mobile test equipment is prepared.
NEDC and WLTP have been buzz words in the automotive industry for several months.
Discussions concerning the diesel engine have significantly heightened awareness of the two test procedures. The abbreviation NEDC stands for "New European Driving Cycle" and refers to exhaust emissions and fuel consumption measurements carried out on a test rig.
With effect from September 1, 2017, this test method has been replaced by the WLTP cycle throughout Europe. Initially, the new procedure only applies to the latest models and engines which are being subjected to type testing for the first time. The new up GTI* is the first example. In the new procedure, the test conditions are more realistic, more comparable and more precise.
1. What precisely is WLTP?
The abbreviation WLTP stands for "Worldwide Harmonized Light Duty Vehicles Test Procedure". The test cycle used is referred to as WLTC (Worldwide Harmonized Light Vehicles Test Cycle).
Fuel consumption and exhaust emissions values are measured in the laboratory.
The new cycle has been introduced to allow CO2 emissions measurements to be carried out on passenger cars and light commercial vehicles internationally on a standardized basis. In addition, the objective is to provide consumers with CO2 emissions and fuel consumption values that have been determined in a more realistic way. To date, various different test procedures have been used throughout the world. This led to additional cost for manufacturers and made it difficult for customers to compare the results.
2. What are the objectives of WLTP?
The objective of the WLTP cycle is to lay down uniform exhaust emissions and fuel consumption test procedures for different types of powertrain (gasoline, diesel, natural gas and electric). In addition, the test cycle is to give a more realistic reflection of real-world driving behavior and not only to measure emissions values. Emissions and fuel consumption values are measured in the laboratory.
Using mobile test equipment: additional measurements under real driving conditions
In addition, an RDE ("Real Drive Emissions") test is carried out to measure exhaust emissions under normal road conditions.
In 2010, CO2 emissions in the EU alone totaled 4.72 billion metric tons, with road traffic accounting for 19 percent. This is why the EU decided to reduce emissions by twenty percent by 2020 (compared with 1990). Compliance with this target is to be verified using WLTP. This way, the new procedure contributes to climate protection and improved air quantity.
3. When is WLTP coming into force?
WLTP is being introduced in two stages: Since September 1, 2017, manufacturers have been under an obligation to test the consumption and exhaust gas emissions values of all newly type-tested models and engines in accordance with WLTP. From September 1, 2018, ALL new vehicles must be tested in accordance with WLTP.
4. What are the differences between NEFZ and WLTP?
5. What are the effects of equipment variants and special equipment?
In contrast to NEDC, WLTP also takes into consideration individual special equipment with effects on weight, aerodynamics and rolling resistance. Currently, special equipment such as air conditioning or seat heating is switched off during the test.
In the WLTP cycle, special equipment such as wide tires must also be taken into consideration.
It is the objective of Volkswagen to provide customers with the WLTP figures, in addition to the NEDC figures already available, during the online configuration of their vehicle. Upon the signature of the vehicle purchase contract, consumption and CO2 values will then be stated by the manufacturer for the specific market. In the EU, the customer will also receive the Certificate of Conformity (COC) as a legal basis for the contract. As already mentioned, special equipment is taken into consideration in the WLTP tests. For example, a panoramic roof increases a vehicle's weight, a rear spoiler changes its aerodynamics and different tires affect the rolling resistance. As a result of these factors, the emissions may either be increased or reduced.
6. Why are weight, aerodynamics and rolling resistance taken into consideration?
The more a vehicle weighs, the higher are its fuel consumption and emissions. In the NEDC, measurements could be carried out without optional extras. This meant that vehicles were lighter, resulting in lower measurements. In the WLTP cycle, special equipment must be taken into consideration. This makes the vehicle heavier and the emissions values higher.
7. Will road tax rise as a result of the higher CO2 values?
Vehicle keepers will only have to pay higher road tax if the new test procedure leads to a higher CO2 figure than the old procedure. Currently, the CO2 share in road tax in Germany is about two euros per g/km.
8. What countries are introducing WLTP?
The test procedure is being introduced by the 28 member states of the European Union as well as other countries outside the EU. The USA participated in the development of the procedure but left the project during the process. India and South Korea will probably only implement parts of WLTP. Discussions as to whether and to what extent to introduce the new procedure are also in progress in Japan.
9. How does the test procedure work?
The test procedure is based on vehicle behavior data from all countries and regions participating in WLTP. A driving cycle with a duration of about 30 minutes was calculated on this basis.
The gear shift points required are calculated for each specific vehicle
As regards key parameters such as acceleration behavior, speeds and standstill times, the procedure is to be representative of all the countries concerned. The WLTP consists of the four cycle phases "Low", "Medium", "High" and "Extra-High". A combined value is also to be stated.
As a general principle, the WLTP cycle simulates a dynamic driving profile, including phases with acceleration, deceleration and standstill. In contrast to NEDC, there are only very few sections with a constant speed. The average speed during the WLTP test cycle is 47 km/h and the distance covered is about 23 kilometers.
10. Where can I find out more about WLTP and the introduction of the procedure at Volkswagen?
Volkswagen information page: Basic principles, comparisons and benefits:
Volkswagen email address:
German Association of the Automotive Industry (VDA)
European Automobile Manufacturers Association (ACEA)
*up! GTI: The near-production concept car has not yet gone on sale and therefore Directive 1999/94 does not apply.