CO2 targets that car manufacturers have to meet by 2021 are based on the old NEDC test, the so-called New European Driving Cycle.
From the introduction of WLTP in September 2017, the WLTP-CO2 values will be translated back to NEDC-equivalent values to monitor compliance against the CO2 targets set by the European Union.
A ‘correlation exercise’ was carried out by the European Commission to determine how the values for new cars measured on the WLTP cycle will be translated back to NEDC equivalent values for monitoring against the EU CO2 targets.
These correlated NEDC values will either be calculated using a correlation simulation tool or based on the results of physical NEDC test.
The correlation tool has limitations that may result in higher NEDC-CO2 values.
If the correlation tool does not confirm a manufacturer’s declared CO2 value or the tool is not able to deal with specific technologies, CO2 values from the correlation exercise can be replaced by physically measured values using NEDC.
However, since this will be an updated version of NEDC (with tightened test set-up conditions), new cars that are type-approved under WLTP will have WLTP-CO2 values as well as higher (updated) NEDC-CO2 values compared to the current NEDC.