How does the Audi A2 achieve its high fuel efficiency?

I noticed that the Audi A2 has a much higher fuel efficiency than other cars in its class. How is this achieved and what technology does it use?

The Audi A2 achieves its high fuel efficiency through the use of lightweight materials and advanced aerodynamic design. These features allow for reduced air resistance and improved fuel consumption.

The Audi A2 also utilizes a regenerative braking system, which captures energy that would normally be lost during braking and uses it to power the car, further improving its fuel efficiency.