5. Audi A2 (1999)
The Audi A2 was a pioneer in sustainable engineering, boasting a lightweight aluminum body that drastically improved fuel efficiency.
Its clever use of materials and aerodynamic design made it one of the most eco-friendly cars of its time.
Though the market wasn’t quite ready for such innovation, the A2’s construction and efficiency foreshadowed today’s industry-wide push toward lightweight, environmentally conscious vehicles.
Source: Autocar