Designed by Tom Tjaarda while he was working at Pininfarina, an experimental safety concept that pre-dated the safety prototypes of the later 60s and 70s. The car incorporated 14 safety features, 8 of which went on to be used in the production of the vehicles in the future. This build has also been referred to as the "Pininfarina Modello PF Sigma Concept."
Additionally, here's a piece from Classic Car Catalogue:
This year there are a few great bodies, notably the Pininfarina Sigma, a unique study on safety requirements undertaken in conjunction with the leading Italian motoring journal Quattroroute. As usual, some of the new exhibits are also more beautiful than practical-two-plus-two does not always add up to four, it seems. Pininfarina has made a very serious study of the safety aspects of body design in the Sigma; it s presented as a complete car, although not based on e specific model, and the ideas can be applied to either front- or rear-engined layouts. The show car is smaller than the average American car but more significant than those most popular in Europe. It has no fancy gimmicks such as unusual steering controls, like so earlier ideas from America. Still, it is planned around orthodox features that are thoroughly practical and would not be costly to apply.
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