Since September 2018, the WLTP (Worldwide Harmonized Light Vehicles Test Procedure) standard is in force and is gradually replacing the old NEDC standard that has been in existence since the 1970s. This new test was implemented by the United Nations Economic Commission for Europe (UNECE) in coordination with India and Japan. These two standards exist to calculate as accurately as possible the fuel consumption and CO2 emissions of each vehicle over a given cycle. In practical terms, it allows you to compare vehicles with respect to their range to make your choice easier. We will therefore see how the WLTP range is calculated, which is referred to in the descriptions of the best-selling electric vehicles in France.
HOW DOES THE WLTP CYCLE WORK?
The WLTP cycle, like the NEDC cycle, takes place on a chassis dynamometer and the car runs a cycle with different speeds, under different conditions to simulate reality as accurately as possible. This is the reason why the WLTP standard appeared, as the NEDC is criticized for not being close enough to reality.
Here are the test conditions compared to the NEDC cycle:
|Cycle time||30 minutes||20 minutes|
|Distance travelled||23,25 km||11 km|
|Average speed||46,5 km/h||34 km/h|
|Maximum speed||131 km/h||120 km/h|
|Temperature||23 °C||20-30 °C|
|Phases||52% in city driving|
48% in extra-urban driving
|66% in urban driving|
34% in extra-urban driving
Here’s a profile of the two cycles:
We can see that the WLTP cycle is much more dynamic, with more rhythm changes, as well as greater speed and distance travelled. In addition, this new standard is more adapted to the vehicle by taking into account its class and its different equipment such as air conditioning or heating to evaluate their impact on the vehicle’s consumption.
AN ESTIMATE OF AUTONOMY
With this new WLTP cycle, which will have completely replaced the NEDC cycle by the end of 2020, the consumption of vehicles is estimated, whether thermal, hybrid or electric. This consumption then makes it possible to determine the WLTP range that is as close to reality as possible. The Renault Zoé, for example, has lost 200 km of autonomy between the two standards (from 600 to 400 km), like many other vehicles. This is still an estimate and the range of your electric vehicle will depend a lot on driving conditions, whether it is the outside temperature, the heating system turned on, the speed, or even the wear and tear of the battery. However, this standard is very useful because it allows you to compare vehicles to better choose the right electric vehicle for your needs.
HOW DO I KNOW WHEN THE BATTERY IS RUNNING LOW?
As with mobile phones, the range of the car will decrease with increasing mileage and battery wear and this is not mentioned in the WLTP standard. This is therefore an important point to look at, especially when buying a second-hand electric vehicle.
To do this, it is possible to have the battery diagnosed, or to do it alone, to know its state, the SOH (State Of Health). It is equal to 100% for a new vehicle but can go down more or less quickly depending on the use of the battery. It is therefore necessary to make this diagnosis to be able to ensure the state of the battery and negotiate according to it.
This diagnosis can also be interesting for guarantees. Indeed, manufacturers offer guarantees on the condition of the battery, such as Peugeot with the e-208. Its battery is guaranteed for 8 years or 160,000 km for 70% of its charge capacity. So if the SOH of your electric car exceeds the guarantee threshold, you can have it repaired or replaced free of charge. It is therefore also interesting to look at this when buying a used car.
For more information on the WLTP standard: https://www.wltpfacts.eu/