How does the Audi A8's energy recuperation system work?

I've been hearing a lot about the Audi A8's energy recuperation system and how it improves fuel efficiency. Can someone explain to me how it works and if it's worth the extra cost?

The Audi A8's energy recuperation system uses a combination of regenerative braking and a coasting function to capture and store energy that is normally lost during braking. This stored energy is then used to power the car's electrical systems, reducing the load on the engine and improving fuel efficiency.

While the energy recuperation system may increase the initial cost of the Audi A8, it can save you money in the long run by reducing fuel consumption. If you're someone who drives a lot in urban areas with lots of stop-and-go traffic, it may be worth considering as it can significantly improve your gas mileage.