The post-COVID era has seen a significant shift in consumption patterns, with increased demand for delivery services. Additionally, advancements in autonomous driving have spurred rapid growth and new trends in the logistics industry. This paper introduces a novel approach to improve the stability of car-trailer systems and enhance fuel efficiency by implementing an in-wheel motor-driven trailer. The controller utilizes an extended Kalman filter for estimating the vehicle's lateral velocity, as it cannot be directly measured. The in-wheel motor torque vectoring controller employs a Linear Quadratic Regulator (LQR) technique, with a linear state-space model derived from the nonlinear equations through linearization at the desired state for each time step. Validation was conducted through simulation and a real road driving test at the Hyundai proving ground, focusing on a single lane change scenario at 72 km/h. Results demonstrate that the in-wheel motor-driven trailer, guided by the torque vectoring controller, enhances lateral stability, even with in-wheel motor torque at half of the simulation model's maximum.