Global warming and the dependance on expensive fossil fuels in uncertain times are two main drivers for the development of alternative drivetrains. The alpine logging sector is no exception. Indeed, electrification has demonstrated significant potential for fuel savings in cable logging applications, particularly due to the high capacity for energy recovery in cyclic operations involving variations in potential energy. This work presents results of a study involving several key sub-systems as well as the roundtrip efficiency of a hybrid self-propelled carriage called HULK. In addition to performance and efficiency studies of the engine-generator unit, energy dissipation unit and battery system, its two main drive systems, i.e., the dropline winch and the propulsion module, have been evaluated. The tests enabled the performance mapping of key components, identification of optimal operating points, and confirmation of the substantial energy recovery potential. Furthermore, the results highlight the feasibility of energy-autarkic operation in real-world transport applications.