The CNOSSOS-EU prediction method, mandatory since 2019 for noise mapping in compliance with the European Noise Directive, specifies the road vehicle noise equations to be used per vehicle category. French noise emission data differ significantly from the European model and a national decree was published in June 2018 to provide CNOSSOS corrective coefficients in accordance with the national NMPB2008 model. However, the European semi-heavy vehicle category is non-existent in both French emission model and databases, thus lacking to support the proposed coefficients at this stage. To provide missing information, detailed measurements under controlled conditions have been performed on a sample group of semi-heavy vehicles. The contribution of propulsion noise and rolling noise were separated and average emission equations were proposed by subcategory. For two traffic composition scenarios, mainly differing by the ratio of public transport vehicles, a noise emission model has been proposed to represent an average medium-heavy vehicle. The paper presents the approach and the models obtained. The representativeness of the European prediction model in its initial version published in 2015, its French adaptation of June 2018 and the European correction discussed in 2018, is considered for both scenarios. Comparisons of frequency characteristics are emphasized.