Audi will be unleashing a total of 20 specially prepared Audi A1 e-tron range extender electric cars onto the streets of Munich as part of the “eflott” joint venture pilot project between Audi, E.ON, the Munich municipal utility company Stadtwerke München (SWM) and the Technical University of Munich (TUM).

The Audi A1 e-tron is powered by a electric motor that delivers an output equivalent of 102 PS, drawing power from a lithium-ion battery mounted within the floor assembly in front of the rear axle of the A1 e-tron. This electric motor can take the A1 e-tron up to a top speed of 81 mph and it can go about 31 miles in city traffic.

But what happens beyond 31 miles? A small combustion engine will be started up to generate power to recharge the batteries, and what’s most interesting is that this small combustion engine is a small single-rotor Wankel rotary engine, with 15 kW of charging output. It would be interesting to find out why exactly Audi chose to use a Wankel rotary engine design for its range extender combustion engine.

Supporting these A1 e-tron cars are a total of 200 newly installed charging stations. These stations will enable experts to address a number of issues, from the data transfer between the driver, vehicle and electric filling station to the power grid and the use of smartphones as the central interface for the driver.

According to a draft standard for the calculation of fuel consumption for range extender vehicles, the A1 e-tron will be able to achieve a fuel economy figure of 148.7mpg and a CO2 output of only 45 g/km.