Recent UE legislations requires that CO2 emissions of newly registered passenger cars should reduce by 55% in 2030. The widespread adoption of electrification powertrains will be needed to achieve these targets. Moreover, the thermal management of the vehicle will play a fundamental role to guarantee that the powertrain will operate with high efficiency. The object of this thesis, made in collaboration with POWERTECH Engineering S.r.l., is therefore the development of a control strategy aimed to optimize both the thermal management and the fuel efficiency of a Plug-in Hybrid Electric Vehicle (PHEV). First, a physical vehicle model, representative of a C-SUV passenger car, is built on the commercial software GT-SUITE.