Since September 1, 2017, new consumption and emissions certification tests have been in force for all new cars to be launched. The WLTP (Harmonized Global Testing Procedure for Light Vehicles) replaces the NEDC (New European Driving Cycle) and what this means, in short, is a more rigorous test cycle that will bring the official consumption and emissions figures closer to those verified in real situations .
But the certification of consumption and emissions will not stop there. Also from this date, the RDE test cycle will join the WLTP and will also be decisive in ascertaining the final consumption and emission values of cars.
RDE? What does it mean?
RDE or Real Driving Emissions, unlike laboratory tests such as the WLTP, they are tests performed in real driving situations. It will complement WLTP, not replace it.The objective of the RDE is to confirm the results achieved in the laboratory, measuring the level of pollutants in real driving conditions.
What kind of tests are carried out?
The cars will be tested on public roads, in the most varied scenarios and will have a duration of 90 to 120 minutes:
- at low and high temperatures
- the low and high altitude
- at low (city), medium (road) and high (highway) speeds
- up and down
- with load
How do you measure emissions?
When tested, a Portable Emission Measurement System (PEMS) will be installed in cars, which allows you to measure in real time the pollutants that come out of the exhaust , such as nitrogen oxides (NOx).PEMS are complex pieces of equipment that integrate advanced gas analyzers, exhaust gas flow meters, weather station, GPS and connection to the vehicle's electronic systems. This type of equipment reveals, however, discrepancies. This is because PEMS cannot replicate with the same level of accuracy measurements obtained under the controlled conditions of a laboratory test.
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Nor will there be a single PEMS equipment common to all — they may come from different suppliers — which does not contribute to obtaining accurate results. Not to mention that your measurements are affected by ambient conditions and the tolerances of different sensors.
So how to validate the results obtained in the RDE?
It was because of these discrepancies, however small, which was integrated in the test results an error margin of 0.5 . In addition, a compliance factor , or in other words, limits that cannot be exceeded under real conditions.
What this means is that an automobile may have higher levels of pollutants than those found in the laboratory during the RDE test.
At this initial stage, the compliance factor for NOx emissions will be 2.1 (ie it may emit 2.1 times more than the legal value), but it will be progressively reduced to a factor of 1 (plus 0.5 margin of error) in 2020. In other words, at that time the limit of 80 mg/km of NOx stipulated by Euro 6 will have to be reached also in the RDE tests and not just in the WLTP tests.
And this forces builders to effectively achieve values below the imposed limits. The reason lies in the risk that the PEMS error margin entails, as it may be higher than expected due to particular conditions on the day that a given model is tested.
Other compliance factors relating to other pollutants will be added later, and the margin of error may be revised.
How will it affect my new car?
The entry into force of the new tests affects, for the time being, only cars launched after this date. Only from September 1, 2019 will all cars sold have to be certified according to the WLTP and RDE.
Due to its greater rigor, we will effectively see a real reduction in NOx emissions and other pollutants and not just on paper. It also means engines that will have more complex and costly gas treatment systems. In the case of Diesels it should be impossible to escape the adoption of SCR (Selective Catalytic Reduction) and in gasoline cars we will see the widespread adoption of particulate filters.
As these tests imply a general rise in official consumption and emissions values, including CO2, if nothing changes in the next State Budget, many models will be able to move up one or two notches, paying more ISV and IUC.