Why is the Audi A2 considered a pioneer in lightweight automotive design?

I've heard that the Audi A2 was one of the first mass-produced vehicles to use extensive aluminum construction. What were the reasons behind this decision and how does it benefit the car's performance and efficiency?

The use of aluminum in the A2 was a key factor in reducing weight and improving fuel efficiency. This allowed for better performance and lower emissions, making it a top choice in its class.