The Active Valve Control System (AVCS) is a variable valve timing engine technology used by Subaru. Using similar ideas as Honda’s VTEC, the system squeezes the best performance from the engine while also minding emission standards. It works by varying the timing of the intake valves and adjusting the positions of the camshafts based on inputs from various sensors in the powertrain. This increases the power output especially on higher rpms without sacrificing fuel consumption.