Determining fuel consumption and emissions more realistically.
The new WLTP process.
Certification processes are also getting long in the tooth. That's why the "Worldwide Harmonized Light Vehicles Test Procedure", WLTP for short, is replacing the NEDC process for determining the consumption and emission values. The "New European Driving Cycle" (NEDC) was initially developed as a theoretical measurement run and has been in application Europe-wide since 1992. A modern certification process should, however, provide values that are as close to reality as possible, with the help of which you can compare various vehicle models. The NEDC process no longer meets this requirement. That's why the new WLTP process was developed by an initiative of the United Nations Economic Commission for Europe (UNECE). The new WLTP cycle is based on empirically collected, real driving data from routes in Asia, Europe and the USA and is thus significantly more representative.
According to Art. 15 Para. 2 and 3 VO 2017/1151/EU, the following introduction dates apply:
- 01.09.2017: new vehicle models for Class M1 and M2 vehicles
- 01.09.2018: new vehicles for Class M1 and M2 vehicles
- 01.09.2018: new vehicle models for Class N1 Group II and III and Class N2 vehicles
- 01.09.2019: new vehicles for Class N1 Group II and III and Class N2 vehicles
New driving cycle and specific values for every vehicle.
NEDC and WLTP compared.
New to the WLTP certification is above all the test cycle and the obligation to disclose specific consumption values for each possible configuration of a vehicle.
When comparing the two test cycles, it is noticeable that the WLTP cycle is closer to reality and more demanding than the NEDC cycle: it takes 30 instead of 20 minutes, acceleration is carried out more often and the time in which the vehicle is at a standstill is significantly reduced. The top speed of 131 km/h is also around 10 km/h above that of the NEDC cycle.
Add to this that the consumption and emission values in the WLTP process are determined specific to the vehicle, as the mass as well as the air and rolling resistance of a vehicle can change depending on the vehicle's equipment. Optional equipment items are also taken into account. For example, if you choose an aerodynamic wheel as a special equipment, this can have a positive influence on the consumption values.
Closer to the consumption on the road.
Advantages of WLTP.
The values determined by the WLTP process will come significantly closer to your fuel consumption on the road than values determined according to the NEDC process. This is down to the new driving cycle, which better illustrates today's driver profiles. Furthermore, the consumption values have to be specifically identified for each vehicle. In other words: in the determination of the certification values, the mass, the air and rolling resistance as well as the optional extras are taken into account.
Nevertheless, WLTP cannot deliver "individual" consumption values. It remains a standardised test cycle, which cannot illustrate the personal consumption of each driver. The actual consumption of your vehicle on the road is largely dependent on the individual driving style, on route profile, on traffic, on the load of the vehicle and on external conditions, such as temperatures. This cannot be entirely reproduced with a standardised test process.