Electric retrofit is an innovative technique to convert vehicles with an internal combustion engine (ICE) into electric vehicles. Retrofitting an older vehicle not only ensures that the user can once again drive a car that would otherwise be out of circulation but also represents a solution against climate change. It reduces CO2 emissions into the atmosphere, and it is a viable alternative to the disposal of the combustion car park. This thesis project aims to develop and optimise a software architecture embedded in a vehicle control unit (VCU), capable of controlling various functions of the retrofitted vehicle, such as its propulsion unit, reducing as much as possible the workload of the motor control unit (MCU) linked to the inverter.