What technology makes the Audi A2 so fuel efficient?

I've heard a lot about the Audi A2 being incredibly fuel efficient. What technology do they use to achieve such high fuel economy, and how does it work?

The Audi A2's advanced aerodynamic design is one of the key factors contributing to its fuel efficiency. By reducing air resistance and drag, it improves the car's overall efficiency at higher speeds.

Another important technology in the Audi A2 is its lightweight construction. This includes the use of aluminum and other lightweight materials, reducing the overall weight of the car and improving its fuel economy.