In engineering terms it was a revolution for Porsche. The structure was not the complex latticework of tubes upon which Porsche had been basing its race cars since the 1956 550A and would continue to do so into the 1980s, but something closer to a baking tray. Porsche designed two steel box sections to run longitudinally under the car, joined by cross members to form a basic structure that weighed just 54kg, yet was stiffer even than the 1962 F1 car. But the clever bit was to bond that glass fibre body to the chassis, increasing its rigidity still further. The result was sufficiently stiff and quite exceptionally light: in full 24 hour trim this very car weighed in at Le Mans in 1964 at 722kg. Driven by double Targa Florio winner Herbie Muller, it came 11th, one of five production 904s to take the start, every one of which saw the finish.
The 904s would probably have done better still if they’d had the engine for which they were designed. The plan was always that they’d carry the new flat-six under their elegant rear cowls, but its slow development for the 911 meant Porsche’s old, fiendishly complex four cam flat-four would be used instead. The six would finally arrive – and the factory even raced the 904 with an F1-derived flat-eight – but only for the end of production. Finally, at each corner sat not the struts, semi-trailing arms nor even swing axles of more traditional Porsches, but double wishbones in purest racing fashion.