How does the Audi A2 achieve such a high fuel efficiency?

I have heard that the Audi A2 is one of the most fuel-efficient cars on the market, with its compact size and lightweight design. But I am curious to know what specific features and technologies contribute to this impressive fuel efficiency. Can you provide some insight into this?

The Audi A2's advanced aerodynamic design plays a significant role in its fuel efficiency.

In addition to its design, the Audi A2 also utilizes a regenerative braking system to capture and reuse energy that would normally be lost during braking.