Audi Duo
At the Geneva Motor Show in March 1990 Audi presented its first iteration of the Audi Duo (or Audi 100 Avant Duo) experimental vehicle, a plug-in parallel hybrid based on the Audi 100 Avant quattro. This car had a 12.6 bhp (9.4 kW) Siemens electric motor which drove the rear wheels. A trunk-mounted nickel-cadmium battery supplied energy to the motor that drove the rear wheels. The vehicle's front wheels were powered by a 2.3-litre five-cylinder engine with an output of 136 PS (100 kW; 134 hp). The intent was to produce a vehicle which could operate on the engine in the country and electric mode in the city. Mode of operation could be selected by the driver. Just ten vehicles are believed to have been made; one drawback was that due to the extra weight of the electric drive, the vehicles were less efficient when running on their engines alone than standard Audi 100s with the same engine.
In late 1991, Audi unveiled the second Duo generation – likewise based on the Audi 100 Avant quattro. Once again this featured an electric motor, a 28.6 PS (21 kW; 28 hp) three-phase machine, driving the rear wheels. This time, however, the rear wheels were additionally powered via the Torsen differential from the main engine compartment, which housed a 2.0-litre four-cylinder engine.
Read more about this topic: Audi 100