Today's mainstream vehicles are equipped with Advanced Driver Assistance Feature (ADAS) known as Adaptive Cruise Control (ACC) to allow for partial automation. ACC uses on-board sensors to automatically adjust speed and maintain safe following distance. Contrary to expectations that automation could relieve congestion, ACC on vehicles powered by internal combustion engines (ICE) could reduce capacity and worsen congestion because its limited initial acceleration during queue discharge could increase the average headway. Fortunately, when ACC is paired with fully electric vehicles (EVs), EV's unique powertrain characteristics such as instantaneous torque and regenerative braking could allow ACC to adopt shorter headways and accelerate more swiftly to maintain shorter headways during queue discharge, therefore reverse the negative impact on capacity. This has been verified in a series of field experiments, model calibration, and microscopic simulations; EVs with ACC could potentially increase capacity by 21.9% compared to their ICE counterpart.