In this article we present a method which indicates the most important parameters of influence concerning the fuel consumption and regulated emissions. Using RDE measurements a consumption map of the vehicle and enhanced mathematical models are created that allow the prediction of fuel consumption and emissions for simulated driving routes. The results show that the simulated fuel consumption fits the measured consumption of the vehicle very good. The deviations between calculated and measured NO2 and NO are relatively high. This is due to the lack of simulation of the emissions aftertreatment which is not possible as the relevant parameters are not monitored. Further investigations are planned for hybrid vehicles, extended environmental conditions and modelling of the aftertreatment.