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Towards more representative measures of the actual use of a vehicle

In a context of strong public sensitivity in respect of the environment and health, regulations are evolving by lowering the maximum emission limits for gaseous pollutants and by defining new test protocols for the approval of new vehicles. Car manufacturers will now be able to communicate more representative emissions and consumption of the actual use of a vehicle.



This is the European emission standard, as known as Euro standard, which sets the maximum limits for emissions of gaseous pollutants for vehicles. Currently, the Euro 6 standard is in force. It frames the programs of:

tiret_bleu  Carbon monoxide (CO)
tiret_bleu  Nitrogen oxides (NOx)
tiret_bleu  Hydrocarbons (HC)
tiret_bleu  Fine particles (PM)

Complying with the requirements of the Euro standard is an obligation for car manufacturers: the approval of a new vehicle is mandatory in order to obtain the registration certificate and allow it to be put on sale.

Homologation consists of a series of tests certifying the regulatory compliance of any new vehicle placed on the market. This includes checking compliance with pollutant emission rules. The application of this standard was controlled by the NEDC (New European Driving Cycle), a reference since the 1990s.

Today, this protocol is no longer in line with the evolution of technologies and driving habits. The NEDC protocol was essentially based on theoretical notions, without taking into account actual driving conditions. The figures announced were not representative of reality.



A new protocol has been put in place to replace the NEDC. The purpose of this change is to communicate emissions and consumption measures closer to reality.

WLTP, laboratory tests :

Standardized, laboratory tests allow comparison between brands and models. They are a common procedure for all manufacturers to measure engine emissions and fuel consumption.

Since September 2017, a new test protocol replaces the NEDC test: the WLTP (Worldwide harmonized Light vehicles Test Procedure).

RDE, road tests :

The WLTP cycle is coupled with a complementary protocol called RDE (Real Driving Emissions), randomly done on the open road.

These road tests make it possible to take into account all the external parameters that cannot be reproduced in the laboratory and that can be met by a driver (weather conditions, temperature variations, terrain, type of road, etc.).

In particular, they measure the emissions of pollutants from the engine (not fuel consumption or CO2). The data collected makes it possible to verify the accuracy of the results obtained with the WLTP protocol.

Compliance factor :

The pollutant emissions observed on the road must remain below the limit values set by the Euro standard, respecting a compliance factor.

Results reporting :

The results of the RDE tests are stored on the manufacturer’s website accessible to the general public on request.


Phase 1 (before the 1st of September 2017) :

The NEDC protocol was used to measure the consumption and pollutant emissions of vehicles using a procedure described by the European directive. This procedure consisted of a battery of rolling tests to which the new vehicles are subjected.

Phase 2 (1st of Septembre 2017 – 31st of Décembre 2018) :

During this phase, new vehicles put on the market will have been approved with NEDC tests and others with WLTP tests. For the latter, the results will be retranslated into NEDC for uniform communication.

Phase 3 (during year 2019) :

All new vehicles put on the market will have passed the WLTP tests. The values of fuel consumption and CO2 emissions will come from these tests. As a result, the reference to NEDC will disappear from any communication.

In the world :

  The WLTP protocol is adopted by the 28 member countries of the European Commission as well as Norway, Iceland, Switzerland, Liechtenstein, Turkey and Israel.

Other countries are introducing standards derived from the WLTP cycle or studying the modalities of its implementation: China, Japan, South Korea, Russia, India and the United States.

WLTP Questions and Answers.

1/ What is the date of implementation for the WLTP protocol ?

This new procedure came into effect on September 1, 2017 for new vehicles, marketed for the first time, and replaces the previous test protocol, NEDC. It is a test carried out on test benches.

Since September 2018, all new passenger cars will have to be homologated according to this new cycle.

2/ Does the WLTP concern vehicles already registered ?

No, the new WLTP protocol does not apply to Alpine vehicles that have already been registered under the NEDC protocol before September 2018.

3/ What are the advantages of the WLTP procedure ?

The WLTP protocol gives the same basis of comparison, whatever the models and their specificities. Thus, it allows a more realistic vision of consumption and polluting emissions.

It aims to create a procedure for vehicle testing in order to move towards international harmonisation of testing requirements.

4/ What is the impact on fuel consumption ?

Actual consumption is not affected by these changes; the actual fuel consumption will always depend on the variety of uses and the driving style of each driver. However, the WLTP cycle allows the homologous consumption to be compared with the average actual consumption of drivers.

The new, more realistic data on the commercial documents will take into account these new indications of consumption and pollutant releases.