According to EU plans, the “New European Driving Cycle” (NEDC) will be replaced starting in 2017 with the more modern standard “Worldwide Harmonized Light Duty Vehicles Test Procedure” (WLTP). The WLTP—which, like the NEDC, is also a cassis dynamometer test—is more consistent with fuel consumption and CO2 emissions in real-life road traffic than the NEDC. This new test cycle will be important to maintain standardized, reproducible and comparable results.

The NEDC increases speed and resistance at a steady and predictable pace—nothing like driving in the real world. WLTP better mimics real driving conditions, with more modern and realistic driving scenarios. It also considers other widely used factors such as air conditioning and seat heaters that drive fuel consumption upwards. As a result, wrote Christian Friis Bach, Executive Secretary of UNECE (the developer of WLTP), the WLTP is more like running up and down in a hilly park with a backpack, rather than a predictable climb up a set of stairs.

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Estimates project that fuel consumption under the WLTP will be 10 to 20% higher than those under the current test cycles.

RDE is complementary to the WLTP, and checks emissions outside of the well-established testing procedures in labs by using Portable Emission Measurement System (PEMS) in on-road testing. The upcoming EU6c Emission Regulation will implement Real Driving Emissions as an additional type approval requirement in the 2017 - 2020 timeframe. 

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