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.

Audi also says the whole assembly of Wankel, generator and electronic controls weighs just 70kg. This engine manages to achieve EU5 emissions levels, but Audi is working on getting it to ultra-clean EU6.

What’s especially nice about this concept is not just the clever engineering, but that the rotary engine was originally developed by Felix Wankel at NSU, one of the companies that merged to form Audi in its modern form. Indeed, the old NSU plant at Neckarsulm currently builds the Audi A8.

The rotary engine was famously fitted to the landmark 1967 NSU Ro80 saloon, which was built under Audi ownership until 1977.

The re-birth of the Wankel engine for use as a tiny, super-smooth, generator in electric cars is just the kind of innovative engineering that I feared Audi had left behind in its focus on dominating the premium car market.

More of this, please, Audi bosses.

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