How does Audi's all-wheel steering system work in the A8?

I've heard that the Audi A8 offers an all-wheel steering option, but I'm wondering exactly how it works and what benefits it provides. Can anyone explain?

The all-wheel steering system in the Audi A8 allows the rear wheels to turn up to 5 degrees in the opposite direction of the front wheels at low speeds. This improves maneuverability and reduces the car's turning radius, making it easier to park and navigate tight spaces. At high speeds, the rear wheels turn in the same direction as the front wheels, providing better stability and control.

I recently test drove an A8 with the all-wheel steering and was really impressed. At low speeds, it felt like the car was almost turning itself. It definitely makes a difference in tight city driving situations.