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Audi A1 e-tron

The Audi A1 e-tron electric car with Wankel rotary engine as a range extender.

The Audi A1 e-tron, on display at the Geneva Motor Show, is an electric car that has a Wankel rotary engine as a range extender.

The small, single-rotor Wankel engine, a technology normally found in Mazdas, is used to increase the range. This ‘range extender’ powers a generator that produces 15 kW of charging power. If the range extender is used to recharge the battery, the A1 e-tron can cover an additional 124 miles of range, in addition to its 31 miles on electric power alone. According to a draft standard for the computation of fuel consumption for range extender vehicles, this represents a fuel consumption of 148.7mpg – a CO2 equivalent of only 45 g/km.

The small single-rotor Wankel has a chamber volume of 254 cc and runs at a constant 5,000 rpm, ie. peak efficiency.

Audi has used a Wankel engine due to the nearly vibration-free and quiet operation, the small dimensions, and the extremely low weight. Together with the generator, which is powered by the Wankel engine and produces 15 kW of electric power, the complete assembly weighs only around 70 kilograms. This weight also includes the special power electronics, the intake, exhaust, and cooling unit, plus the insulation and the subframe.

Although the A1 e-tron concept car has a Wankel engine as a range extender, Audi says that other compact concepts are also possible.

The battery is comprised of a package of lithium-ion modules mounted in the floor assembly in front of the rear axle. With 102PS the A1 e-tron can reach 62mph in 10.2 seconds and has a speed of more than 80 mph.

Audi calls the A1 e-tron a Mega City Vehicle (MCV) and says that it’s nearly production-ready. The first e-tron, which debuted at the 2009 IAA in Frankfurt/Main, is a near-series high-performance sports car with electric motors for all four wheels. The study shown at the Detroit Motor Show in 2010 is a lightweight, compact two-seater with two electric motors on the rear axle. The Audi A1 e-tron now presents another approach – a compact electric car in the premium class.

The four-passenger, two-door MCV city car was designed specifically for use in the urban areas of Europe and North America and in the rapidly growing megacities of Asia and South America.

Update: Audi A1 e-tron to go on trial in Germany (September 2010) – 20 electric cars to be trialled on the streets of Munich in 2011 as part of the ‘ eFlott project ‘, which forms part of the ‘Model Region Electromobility Munich’ initiative sponsored by the German Federal Ministry of Transport.