The testing measures for car pollutants, emissions and fuel consumption are changing. That’s because the old system, the so-called New European Driving Cycle (NEDC) introduced in the 1980s, has become outdated. It will gradually be replaced by the Worldwide Harmonised Light Vehicle Test Procedure (WLTP). Whereas the NEDC was based on theoretical driving, the new laboratory test is designed to give a more accurate picture of fuel consumption, pollutants and CO2 emissions in passenger cars. The WLTP was launched as a global test cycle across different world regions to make data more comparable worldwide. It is gradually being rolled out across the European Union and other regions worldwide. From September 2018, all new cars must be certified according to the WLTP standard.
The new WLTP test aims to provide more accurate comparable vehicle data that better reflects realistic driving conditions. For example, while the old NEDC standard only covered two driving scenarios (urban & extra-urban, to give a combined value) - the WLTP driving cycle is divided into four parts with different average speeds: low, medium, high, and extra high, to give a combined value of all scenarios. Each part contains a variety of driving phases, stops, acceleration and braking phases. For a certain car type, each powertrain configuration is tested with WLTP for the car’s lightest (most economical) and heaviest (least economical) version. It also takes into account the effects of optional equipment on weight and aerodynamics etc. As a result, both the test distance and the overall duration of the procedure have been extended. The combination of all these new measures should offer a real-world picture of a car’s performance on the road. Even so, it is important to bear in mind that the test is still based on lab data. WLTP cannot measure individual variables like personal driving style which can also impact fuel consumption and emissions.