Euro 6 is the European regulation that limits polluting emissions from road vehicles. Since 2014 it has imposed drastic reductions in NOx (-67%) and particulate matter on diesel compared to Euro 5.
Euro 6 versions
- Euro 6b (2014): first version
- Euro 6c (2017): WLTP test introduced
- Euro 6d-temp (2019): RDE (Real Driving Emissions) introduced
- Euro 6d (2021): RDE strict, reduced conformity factor
- Euro 6e (2024): further tightening
Chiptuning implications
- All Euro 6 cars have DPF + EGR
- Euro 6 diesels have SCR + AdBlue
- More complex systems = more failure points = more tuning requests
Real limits
- Diesel NOx: 80 mg/km (vs 180 of Euro 5)
- NOx petrol: 60 mg/km
- Particulate matter: 4.5 mg/km
RDE and road test
In addition to the WLTP laboratory cycle, from Euro 6d-temp the RDE (Real Driving Emissions) test is mandatory, which measures emissions in real conditions with a portable PEMS analyser. This has forced manufacturers to make the anti-pollution systems (EGR, SCR, DPF) work effectively in all conditions, not just during the test.
Consequences for chiptuning
More systems and more severity mean more "strangled" series engines to stay within the limits, and therefore potentially large optimization margins with a well-made Stage 1. At the same time, the points of possible failure are growing (NOx sensors, SCR pump, EGR valve), which explains the increase in requests for assistance and tuning on recent diesels.
What changes for the customer
For those who own a Euro 6 diesel, the combined presence of DPF, EGR and SCR means more components subject to wear and failure than in the past. For the shop, recognizing the Euro 6 phase (b, c, d-temp, d, e) helps predict which systems are present and how conservative the factory calibration is. This caution, dictated by WLTP and RDE, is also what leaves room for well-done optimization.