Hybrid before it was cool - Audi duo

The Audi Duo III was introduced in 1997, based on the Audi A4 Avant, and was the only Duo to ever make it into series production.

The Duo III used the 1.9-litre (120 cu in)Turbocharged Direct Injection (TDI) diesel engine producing 66 kW (90 PS; 89 bhp), which was coupled with a 21 kW (29 PS; 28 bhp) water-cooled electric motor. Both engine and motor powered the front wheels only, unlike the two previous concept Duos. There was a switch inside the cabin for changing between the electric motor and the engine.

The batteries would be recharged during highway or country driving, or by plugging the car into an AC power outlet. The electric motor could also recover energy during deceleration and in electric mode the Duo had a range of approximately 50 kilometers (31.07 miles) and a top speed of 80 km/h (49.7 mph).