Inter-Comparison of Particle and Gaseous Pollutant Emissions of a Euro 4 Motorcycle at Two Laboratories

The Euro 4 regulation, applicable since 2016 for L-category vehicles (i.e., two and three-wheelers, and mini cars) reduced the emission limits, but also introduced a new cycle, the WMTC (World Harmonized Motorcycle Test Cycle). The emission studies of Euro 4 motorcycles are limited, and most importantly there are no published studies comparing the results of different laboratories applying the new cycle. In this study we compared the particle and gaseous pollutants of one Euro 4 motorcycle measured in two laboratories in 2017 and 2020. The gaseous pollutant results had a variance (one standard deviation of the means) of 0.5% for CO2, 4-19% for CO, NOx, HC (hydrocarbons) and SPN (Solid Particle Number). The particulate matter mass results had higher variance of 50-60%. Additional tests with open configuration to mimic dilution at the tailpipe gave equivalent results to the closed configuration for the gaseous pollutants and SPN. The total particles (including volatiles) had significant differences between the two configurations, with the closed configuration giving higher results. The main conclusion of this study is that the new procedures have very good reproducibility, even for the SPN that is not regulated for L-category vehicles. However, the measurement of total particles needs attention due to the high sensitivity of volatile particles to the sampling conditions.

Automated summary

The Euro 4 regulation introduced new emission limits and a new test cycle for L-category vehicles. This study compared the emissions of one Euro 4 motorcycle measured in two laboratories in 2017 and 2020, finding low variance in gaseous pollutants but higher variance in particulate matter results. Additional tests showed good reproducibility for gaseous pollutants and Solid Particle Number, but highlighted the need for attention in measuring total particles due to their sensitivity to sampling conditions.