AUTOCARS COLECTION 2011

There are precious few cars whose anniversaries call for celebration on Goodwood Festival of Speed four decades down the road – but this year is the Porsche 917's 40th birthday. On Saturday and Sunday, the Goodwood Festival of Speed marks the occasion with the largest gathering of 917s ever seen in Britain, including short- and long-tailed cars and CanAm derivatives.

And yet, while most enthusiasts will know about the 917 and its fearsome reputation, it's harder to explain to the layman why its cult status has endured. The car had a competitive life of just two years and there have been faster and more successful cars before and since – many of them from the same company – so why has the 917's fame survived for so long?