Fans of Porsche will doubtlessly be familiar with its Panamera sedan, which was revealed in 2009 and surprised some long time fans of the company, since it integrated a four door setup rather than the traditional two door sports approach taken by the German manufacturer.

However, visitors to the Pebble Beach Concours d'Elegance last month, will have been able to see a prototype vehicle, which proved that Porsche had had its heart set on creating a four door sedan much earlier than you might imagine.

This is because one of the classic cars on show at the event was the Porsche 928 H50 Concept, which had never been publically displayed at an event of this kind, before its debut in August.

The 928 H50 is unsurprisingly based on the stock 928, but its body has been stretched in order to accommodate not only rear seats, but also individual doors, which provide access to them.

It was designed and built in 1987 and Porsche went so far as to test drive this example for 5,000 miles, although in the end, it did not get put into full production. With a 330hp V8 engine it was certainly no performance slouch, although it remains a reminder of how different things might have been, if prototypes reached production.