 In 1989, Audi produced its first iteration of the Audi Duo (the Audi C3 100 Avant Duo) experimental vehicle, a plug-in parallel hybrid based on the Audi 100 Avant quattro.This car had a Siemens electric motor which drove the rear roadwheels.A trunk-mounted nickel-cadmium battery supplied energy to the motor that drove the rear wheels.