How does Audi's cylinder-on-demand technology work in the A8?

I've heard that the Audi A8 has a cylinder-on-demand feature which shuts down cylinders when not needed. How does this work and does it affect the performance or fuel efficiency of the car? Thanks!

The Audi A8's cylinder-on-demand system works by deactivating cylinders when the car is cruising at a constant speed, such as on the highway. This reduces the number of cylinders being used and therefore decreases fuel consumption and emissions. It does not affect the performance of the car as the system automatically reactivates all cylinders when needed.