Furthermore, it is hypothesised that the differences in PM emissions made by injection system (pressure and injector condition) are more significant than the differences made by the composition of commercial gasoline fuels on the market. The data from Honda shows that the PM Index of 80% of worldwide commercially available gasoline fuels is within the range of 1–2.2, indicating a difference of up to 54.5% in the corresponding PM emissions. The difference made in PM emissions by the injection system is up to 88% in this study. However, this hypothesis requires further and comprehensive investigation.