This paper focuses on the potentials of a Belt-Starter-Generator (BSG) in the context of an ultra-light vehicle prototype with a target curb weight of only 600 kg. Therefore, two hybrid approaches with a voltage level below 60 V are described and their potentials regarding electrical driving and CO2 reduction are analysed in detail.Introducing the ‘Cars Ultra-Light Technology’ (CULT) project, the holistic lightweight approach is described as a main requirement for the further hybrid investigations. In addition, a P2-hybrid structure with a 12 V BSG on the transmission input shaft enabled unique features despite the low voltage level and limited electrical power resources. The CO2 reduction for this powertrain combination is described and compared to a conventional stop start configuration. The validation process on a dynamic test rig is presented as well.As a next evolution step, the potentials when integrating a 48 V BSG in such a low weight vehicle are analysed and compared to those of a vehicle with a higher curb weight. Due to the extended hybrid functions, an efficiency based operating strategy is presented managing the use of the internal combustion engine (ICE) and the BSG in an intelligent way. Furthermore, the CO2 reduction in the NEDC and WLTP is calculated and the advantages of a 48 V Plug-In concept are presented.