The introduction of Digital Automatic Coupling (DAC) is recognized as a means of improving the performance of rail freight transport and competitiveness in the freight transport market. In order to increase the awareness and willingness of stakeholders to invest in the introduction of DAC, the benefits of DAC introduction for railway performance should be quantified. The aim of the study is to demonstrate and confirm the positive impacts of DAC introduction, namely the reduction of train handling time in the marshalling yard, the increase in capacity and the improvement of the efficiency of rail sections with longer trains. Based on different methods, data sources and assumptions, three different case studies were carried out for this purpose. In the first case, the impacts of DAC on train handling in the marshalling yard were analyzed. In the second case, the impact of DAC on capacity improvement was analyzed through the scenarios. In the third case, the Data Envelopment Analysis (DEA) model was applied to estimate the impact of longer freight trains enabled by DAC on the rail efficiency. The results of the first case show that DAC can save time in train handling in the marshalling yard, especially when DAC type 5, which even enables an automatic and remote uncoupling process, is used. A look at the results of the scenarios in the second case shows that due to the DAC and the reduced time needed for train handling, more trains can be used on the line, which increases the capacity of the line. The results of the third case show an improvement in rail freight efficiency due to the increase in the length of trains made possible by the introduction of DAC. The overall results therefore show that the introduction of DAC brings benefits that improve rail efficiency and overall competitiveness in the transportation market.