How does cylinder deactivation technology work and improve fuel economy?

Cylinder deactivation (Active Fuel Management, Multi-Displacement) closes intake and exhaust valves on selected cylinders under light load, allowing the remaining cylinders to operate at higher, more efficient loads. Deactivation is achieved through collapsible valve lifters or switchable cam lobes. Benefits include 5-10% fuel savings at highway cruise. Challenges include NVH management (balance shaft, active mounts), seamless transitions, and maintaining emissions compliance. Dynamic cylinder deactivation in some engines can skip any cylinder based on real-time optimization.