This paper presents a control method for tracking electric ground vehicle planar motions while achieving the optimal energy consumption. Sliding mode control and an energy-efficient control allocation (CA) scheme are synthesized to track the desired vehicle longitudinal, lateral, and yaw motions. By explicitly incorporating actuator efficiencies and actuator operating modes into the coordination of redundant in-wheel motors equipped on electric ground vehicles, vehicle planar motion control and operating energy optimization are achieved simultaneously. Different maneuvers are tested for comparisons between the standard and the energy-efficient CA schemes. Based on experimental data and some reasonable assumptions on the efficiencies of in-wheel motors, the energy-efficient CA dictates different torque distributions on all the wheels under consideration of different efficiencies. Simulation results indicate that, in comparison to the results by the standard CA scheme, less energy is consumed when the energy-efficient CA scheme is applied for controlling the electric ground vehicle planar motions.