There are several challenges of automobile industry development. One of the most evident ways is the reducing car weight by using polymeric materials for the construction of the main vehicle’s components. The paper considers the model to calculate the permeability of the vapour components by diffusion and solution through the polymer material. The time of the stationary state is determined. The theory was examined by the experimental study on the example of nitrogen permeation through polytetrafluoroethylene. The experimental results are in satisfactory agreement with the calculations. The diffusion coefficients based on the structure of the polymer were examined. In case of non-experimental data evaluation it can be performed by numerical methods.