In the mid-to-late 1990s, Audi introduced new technologies including the use of aluminium construction. Produced from 1999 to 2005, the Audi A2 was a futuristic super mini, born from the Al2 concept, with many features that helped regain consumer confidence, like the aluminium space frame, which was a first in production car design. In the A2 Audi further expanded their TDI technology through the use of frugal three-cylinder engines. The A2 was extremely aerodynamic and was designed around a wind tunnel. The Audi A2 was criticised for its high price and was never really a sales success but it planted Audi as a cutting-edge manufacturer. The model, a Mercedes-Benz A-Class competitor, sold relatively well in Europe. However, the A2 was discontinued in 2005 and Audi decided not to develop an immediate replacement.