With the implementation of WLTP and the corresponding highly dynamic RDE tests, different engineering methodologies from virtual calibration approaches to Engine-in-the-loop (EiL) operations have to be considered to define and calibrate efficient exhaust treatment technologies without prototype vehicles in early project phases. Since different types of testing facilities can be used, the effects of test benches as well as real and virtual operators have to be determined. Moreover, the reproducibility of test cycles is essential for an accurate and efficient application of exhaust treatment and calibration of engines in order to reduce harmful emissions. In this paper initially the influences of different human drivers on the particle count of a small passenger car with a highly charged, natural aspirated small three-inline-cylinder gasoline engine are presented. The measurement results of one human driver in comparison to a virtual driver regarding the reproducibility are shown additionally. In this setup up several particulate measurement systems with different measurement procedures are taken into account to validate the results. In the second part, including the same engine and measurement systems, the effects and influences of seasonal gasoline RON 95 (winter and summer) on the size distribution (5,6 – 560 nm) and count of particulate are discussed. By the introduction of Euro 6d there is no more legislation concerning the fuel used for RDE emission testing purposes. Therefor it has be taken into account that due to seasonal weather changes specifically designed fuels are sold as at regular gas stations. Although summer and winter fuels are supposed to guaranty the same physical properties, they differ in composition which leads to considerable differences in particulate emissions. A mixing of the different weather-dependent fuel types in the tank is avoided by clearing it extensively before refilling it with the next test fuel. As prescribed all fuels are bought at public gas stations and have been tested by a third-party laboratory to guarantee the immaculateness of each fuel type.