The latest electric vehicles (EVs) are becoming increasingly complex and resource-intensive owing to their advanced functional capabilities and autonomy. In this study, EVs are considered as cyber-physical systems (CPS), and a novel event-triggered sliding mode controller (ET-SMC) with a hierarchical framework is developed to enhance lateral stability and reduce communication resource consumption in EVs through torque vectoring control (TVC). The high-level controller of the ET-SMC is designed based on a nonlinear vehicle model, and its stability is rigorously proven using the Lyapunov and input-to-state stable (ISS) theorems. Additionally, a traditional periodic sliding mode controller (SMC) is developed as a benchmark controller. The Sine-with-Dwell (SwD) test scenario, an internationally recognized method for verifying lateral stability, is employed to evaluate the control performance using a hardware-in-the-loop (HIL) test bench. The experimental results demonstrate that the ET-SMC can not only maintain similar control performance in enhancing lateral stability but also reduce controller communication resource consumption by approximately 30% compared to the periodic SMC in this typical driving scenario. These results show that the proposed control algorithm is promising for future EVs.