In the current context, hybrid vehicles play crucial roles in the transition to sustainable mobility. Thanks to recent research progress, even the most deeply rooted design criteria and the most established technologies may need an overhaul, with the key objective of maximizing efficiency. An example is Turbo Compound technology. Originally developed in mechanical form, it evolved significantly during the electrification era. Although it was considered a very promising solution for several decades, its application in the passenger car sector today is marginal. Within these premises, the thesis introduces and explores the novelties and possibilities offered by a new patented electric turbo compound layout with supercharging capabilities, i.e., the TGEMS System (Turbo Generator Electric Multistage Supercharger), a technology that aims to become a reference in the Mild and Full Hybrid cars sector.