Where TbF, TbR are the front and rear braking torques, FbF, FbR are the front and rear braking forces.In a compromise between the energy efficiency and safety during braking, two cases are considered with different strategies. The first case takes into account slight and medium braking processes when safety is not a problem, only two motors are therefore used to improve energy recovery (TbF 0). Conversely, emergency situations require to involve the front mechanical braking system to slow down the vehicle safety. In this case, braking torque allocation is based on the entire utilisation of tyre-to-road adhesion as [36, 40]: