Why does the Audi A6 have a 48-volt mild-hybrid system?

I've noticed that the new Audi A6 comes with a 48-volt mild-hybrid system. What is the purpose of this system and how does it benefit the car?

The 48-volt mild-hybrid system in the Audi A6 helps to improve fuel efficiency and reduce emissions. It also provides additional power for acceleration and smooth starts.

The 48-volt mild-hybrid system also allows for the use of start-stop technology, which shuts off the engine when the car is at a standstill, further reducing fuel consumption and emissions.