Backing up a trailer can be a daunting task, even for experienced drivers. The main challenge being the unstable property of car-trailer kinematics when reversing. With steer-by-wire systems, the mechanical connection between the steering wheel and the road wheels is replaced by an electrical connection. This means that road wheels no longer have to be directly connected to the steering wheel input. The aim of this paper is to help the driver to steer the trailer directly by stabilising the car-trailer kinematics during reversal. This is achieved by developing a steer-by-wire system coupled with a closed-loop trailer reversal control using the necessary feedback. How to obtain this feedback is further investigated in this paper as well as how to use the steering wheel input and torque feedback to interact with the backup assist function. The developed control and user interaction is subjectively and objectively evaluated using computer simulation and a physical prototype of a vehicle equipped with steer-by-wire. The results from the simulation experiments demonstrate that drivers with and without experience of driving a trailer can do the wanted manoeuvres with higher accuracy as well as within a short time span with the controller that is developed in this work. The results from the real life experiments also appears to indicate that the system can remove stress from the driver and move the trailer in an accurate way during a parking manoeuvre.