How do I activate the auto start-stop function in my Audi A6?

I have a new Audi A6 and I noticed there's an auto start-stop function. I'm curious to know how to activate it and if it's worth using. Any insights?

To activate the auto start-stop function in your Audi A6, simply press the button on the center console with the letter 'A' and a circular arrow. This feature turns off the engine when the car comes to a complete stop, reducing fuel consumption and emissions. However, it may be more useful in stop-and-go city traffic rather than open highways.