In recent years, the research in the automotive industry focused on finding alternative solutions to conventional internal combustion engines, to cope with the depletion of fossil fuels and to reduce the amount of CO2 emissions. In this context, Hybrid Electric Vehicles seem to be the most promising solution in the short-term future. In such vehicles, the traction effort is provided by summing the contributions of an internal combustion engine and an electric motor. Given the structure of the powertrain, a complex control strategy is needed to properly manage and optimize the torque-split between the engine and the motor. The introduction of a suitable torque-split optimization strategy leads to performance improvement in terms of fuel consumptions with respect to conventional vehicles.