What is WLTP?
The Worldwide Harmonised Light Vehicle Test Procedure, or WLTP, as initiated from September 2017, is a test used to measure fuel consumption, CO2 emissions, and pollutant emissions to produce an up to date EU fuel efficiency rating for all petrol & diesel cars. The WLTP test also accurately aims to measure the energy consumption values & ranges of all electric cars.
How does it differ from the old, NEDC test?
The WLTP supersedes the old test, “The New European Driving Cycle” or NEDC, which was a test designed in the 1980s. Due to changes in driving conditions, as well as evolutions in technology, the NEDC test became outdated, which led to criticism for producing economy-figures which are unachievable in present-day reality.
The WLTP test aims to deliver real-driving date based on real-world conditions, which is achieved by testing consumption measurements based on what drivers are likely to experience on the road. These more realistic testing conditions include;
- Higher average maximum speeds
- Longer test distances
- More realistic driving behaviour
- Dynamic testing equipment, provided for individual vehicles.
- Stricter measurement conditions
Also unlike the previous, NEDC test, the WLTP will take into consideration the following factors;
- Road type
- Weather conditions
- Traffic conditions
- Road Gradient
Will these factors make a difference to the fuel economy ratings of each vehicle though, and if so, how much so?
How will the new test effect fuel economy figures?
It is predicted that most of the cars on sale in the UK, do not accurately achieve their reported fuel economy figures tested under the old NEDC regulations. So therefore, when considering the changes that the new WLTP test is introducing, it is significantly likely that fuel economy figures will change notably.
Automotive industry data supplier Jato, compared NEDC and WLTP figures for 18 models tested under both systems, and they reported an 5% change in claimed economy between the two tests.
Overall by focusing on more dynamic real-world driving data the WLTP will represent a more complete driving profile, which will as a result be more accurately reflected in the fuel economy figures.