The main question this paper aims to address is whether a lane-keeping controller can serve as a safety feature in order to increase handling and stability of car-trailer combinations. The derivation of a nonholonomic car-trailer model is provided and its open-loop stability is analyzed. A look-ahead based lane-keeping controller is applied to the system, and a comparison is made between the closed-loop stability of an individual car and a car-trailer setup. The critical speed of the vehicle combination is shown as a function of various trailer parameters, with and without the lane-keeping controller enabled. A modified version of the controller is also tested, utilizing feedback of the trailer states. This ensures that the trailer is also kept at the center of the lane, but no improvement was found in terms of stable trailer configurations.