If you asked the Audi show stand staff nicely, they would unlock the hatchback of the A1 e-tron and let journalists gaze, briefly, into the boot.

Cut into the floor was a glass window exposing a tiny, jewel-like, Wankel engine. Beautifully styled, the effect was a combination of religious icon and sci-fi meets NASA.

The e-tron was my favourite exhibit at Geneva, because the thinking behind this little self-charging electric car is a return by Audi to both true ‘Vorsprung Durch Technic’ as well as its historic roots.

The A1 e-tron substitutes its transversely mounted internal combustion engine for an electric motor driving the front wheels.

The 12 kWh battery pack is stored down the floorpan’s centre tunnel and under the rear seat. It gives the car a 31-mile range on pure electric drive, which means zero emissions and pollution from the tailpipe.

However, the e-tron, like the Chevy Volt, can also trickle charge its own battery pack using a petrol engine. Which is where Audi have been very clever, utilizing a tiny rotary (or Wankel) engine, which can fit under the boot floor.

With a single rotor and sized at just 254cc, the 20bhp rotary engine runs constantly at an ideal 5000rpm and should be very quiet and very smooth.