The Euro VI Step E emission standard for heavy-duty vehicles (HDVs) is the first step to introduce cold-start emissions analysis as part of the on-road In-Service Conformity (ISC) requirements. The intention is to reflect the engine cold-start requirements foreseen in the World Harmonized Transient Cycle (WHTC) type approval cycle. In addition, a limit is introduced for solid particle number (PN) to be measured with Portable Emissions Measurement Systems (PEMS). The new regulatory step continues using the Moving Averaging Window (MAW) data post-processing prescribed by the Euro VI regulation, with additions to consider the cold-start emissions.
In order to have a full understanding of the vehicle emissions performance during their daily operation, this study presents emissions data analysis of 25 Euro VI A-C and 3 Euro VI D vehicles. The aim is to screen for potential remaining high emission events during the day-to-day operation. The measurements were conducted throughout the year covering a variety of temperatures and road conditions. The data has been analyzed both in raw form and using an MAW post-processing consistent with the European Union (EU) regulation (either EU 582/2011 for Euro VIA-C or EU 2016/1718 for Euro VI D vehicles).
The results show that overall low oxides of nitrogen (NOx) emissions are achieved in the daily operation. There are, however, remaining high NOx emissions events, mainly within the urban operation. These are not fully considered by the regulatory procedure and therefore usually do not contribute to the final declared emissions for vehicle compliance.
The definition of the European Commission proposal for the heavy-duty Euro VII emissions regulation is ongoing, and the discussion on vehicle compliance is shifting from structured ISC on-road test trips to actual daily operations. This shift emphasizes the need to reduce pollutant emissions in a wide regime of operating conditions in order to minimize exposure of citizens to pollutants. In this context, this analysis contributes to the thorough understanding of the areas where emissions control of HDVs can still be improved.