The use of fossil fuels becomes more and more controversial. Human health issues, environmental impacts, economical conflicts are direct consequences of these sources of energy. Nevertheless, they are deeply rooted in the society, making the transition to greener technologies a real challenge. Fossil fuels industries are not completely transparent, meaning that the composition of final price is unclear. The aim of this project is to describe a model that allows to estimate the breakdown of the fossil fuels cost. The analysis is based on open-source data from the literature. In order to complete the breakdown, the remaining unknown costs are estimated using strategies developed in this project. Applied to the case of Switzerland, the results show that for mobility fuels, around 30% of the price concerns abroad processes and 20% are estimated to be direct margin for the exporting countries. Finally, the import of petroleum products to Switzerland, alone, amounts to 6 billions CHF in 2019.