A steering system (100) and a control algorithm for vehicle servo-steering which acts so that a steering-wheel torque applied by the driver is transformed to a vehicle behaviour. The steering system (100) consists of a steering rack (124), and tie rods (125) connected to the steered wheels of the vehicle (127). The vehicle's steering wheel (120) is connected to the rack (124) via a steering column (121). The steering column (121) contains a torsion bar (128) with a torque sensor in order to measure the steering torque applied by the driver. An assistance torque is given by an actuator (115) which is controlled by a control system (110). The control system (110) contains a control algorithm which translates the steering torque applied by the driver to a reference value in the form of a yaw and/or lateral vehicle state. The servo-system is controlled so that this reference value is attained