The goals to reduce greenhouse gas emissions in the heavy-duty vehicle segment require the use of alternative powertrain systems and improvements of existing technologies. One option that is discussed in this paper is the use of electrified semi-trailer systems. These systems can help to reduce the in-use greenhouse gas emissions of heavy-duty trucks in combination with conventional tractor vehicles. The paper shows the potentials of this technology based on simulation studies and testbed measurements. The influence of the electrified trailer system on the behavior of the combustion engine in the tractor vehicle is taken into account including an assessment of the influence on the exhaust gas aftertreatment system and the resulting pollutant emissions. Based on the testbed results the potentials of a pre turbo catalyst (PTC) system for the considered vehicle are evaluated using an AI-based modelling approach for the thermal behavior of the catalyst. In a final well-to-wheel-analysis the CO2 saving potentials of the electrified trailer system are shown for the use of conventional diesel as well as for the use of hydrotreated vegetable oil (HVO) in the tractor vehicle.