The car was designed by chief engineer Hans Mezger under the leadership of Ferdinand Piëch and Helmuth Bott. The car was built around a very light spaceframe chassis (42 kg (93 lb)) which was permanently pressurised with gas to detect cracks in the welded structure. Power came from a new 4.5-litre air-cooled engine designed by Mezger, which was a combination of 2 of Porsche's 2.25L flat-6 engines used in previous racing cars. The 'Type 912' engine featured a 180° flat-12 cylinder layout, twin overhead camshafts driven from centrally mounted gears and twin spark plugs fed from two distributors. The large horizontally mounted cooling fan was also driven from centrally mounted gears. The longitudinally mounted gearbox was designed to take a set of four or five gears.
To keep the car compact despite the large engine, the driving position was so far forward that the feet of the driver were beyond the front wheel axle. The car had remarkable technology. It was Porsche’s first 12-cylinder engine and used many components made of titanium, magnesium and exotic alloys that had been developed for lightweight "Bergspider" hill climb racers. Other methods of weight reduction were rather simple, such as making the gear shift knob out of balsa wood, some methods were not simple, such as using the tubular frame itself as oil piping to the front oil cooler.