Recent developments show the trend to a single dielectric oil-based fluid cooling & lubrication system vehicle architecture as an oil offers the unique possibility to cool directly electrical components (e.g. motor windings; inverter power electronics and battery cells). These direct cooling techniques lead to an increase in power density e.g. up to 50% for the motor vs. a standard water-cooled solution. Apart from the direct cooling advantage, introducing a single dielectric multi-purpose e-fluid in the complete vehicle will lead to a more integrated, i.e., power dense, and therefore energy efficient and low-cost solution. Furthermore, the use of dielectric fluids leads to an inherent safer drivetrain vs. a water- based solution as any water leak can directly lead to a catastrophic failure, e.g., short circuit in a battery package. However, several challenges remain to introduce dielectric fluids in a complete EV architecture. Therefore, the project aims at developing a smart controlled and optimized thermal single oil vehicle system validated under realistic driving and fast charging conditions. This includes the identification of the best performant thermal architectures, the development of novel direct-contact cooling methods for batteries, inverters, on-board chargers, etc. with special oil-based fluids and a robust design method for fluid-system compatibility. The project re-uses recently validated design tools, innovative robust direct oil motor cooling methods, and dedicated HiL infrastructure for validating the developed novel concepts and models.