 The Audi Duo III was introduced in 1997, based on the Audi B5 A4 Avant, and was the only Duo to ever make it into series production.The Duo III used the 1.9-litre Turbocharged Direct Injection (TDI) diesel engine, which was coupled with a electric motor.Due to low demand for it because of its high price, only about sixty Audi Duos were produced.