Why does the Audi A2 have such a lightweight design?

I've noticed that the Audi A2 boasts a lightweight design compared to other cars. How was this achieved and what advantages does it offer?

The Audi A2 features a unique aluminum space frame that reduces weight and increases stability. As a result, the car is more agile and fuel-efficient.

The lightweight design of the Audi A2 was achieved through the use of advanced materials such as aluminum and carbon fiber. This not only improves performance but also makes the car more environmentally friendly.