The WLTP (Worldwide Harmonized Light Vehicles Test Procedure) is the laboratory test cycle to approve the consumption/emissions of light vehicles. Since September 2017 it has replaced the old NEDC (1980).
WLTP vs NEDC differences
- Test duration: 30 min (vs 20 min NEDC)
- Average speed: 46 km/h (vs 34)
- Max speed: 131 km/h (vs 120)
- More realistic → declared consumption 15-25% higher
WLTP and RDE
WLTP is in the laboratory. RDE (Real Driving Emissions) measures real-road emissions with portable PEMS — even more stringent. Combined, they have forced manufacturers to more aggressive anti-emissions systems (more SCR/EGR/DPF).
Chiptuning implications
WLTP/RDE cars have more "careful" ECU calibration to pass the tests → higher tuning margins, because the engine is strangled at the factory.
WLTP and RDE together
The WLTP measures consumption and emissions in the laboratory with a cycle longer, faster and more realistic than the old NEDC, while the RDE test verifies them on real road with a portable analyzer. The combination of the two has made it much more difficult to "optimize for the test", forcing manufacturers to make the anti-pollution systems work well in all driving conditions.
Effect on tuning margins
To stay within these limits, the engines are calibrated as standard in a conservative way, often leaving margins that can be exploited by a well-done remapping. At the same time, the greater complexity (SCR, EGR, DPF/GPF, more sensors) increases the points of possible failure and therefore the requests for assistance. Correct tuning improves performance and driveability without compromising the compliance of the emission systems required for road use.
In summary for the workshop
For the customer, the result counts; for the workshop it is important to understand why there is margin: the prudent calibration imposed to exceed WLTP and RDE leaves room for well-done optimization. At the same time, the complexity of emission systems makes breakdowns and requests for assistance more frequent. Correct tuning enhances this margin by improving driveability and performance, without altering the anti-pollution systems intended for road use.