The Porsche 906 or Carrera 6 was the last street-legal racing car from Porsche. 65 were produced in 1966.
A successor to the Porsche 904, and designed under Ferdinand Piëch’s new regime at Porsche R&D, the 906 replaced the boxed steel structure of the 904 which used the fiberglass body for extra structural strength with a tubular space frame and unstressed fiberglass body. The fiberglass itself was laid up by hand, producing consistent results, instead of the uneven spraying technique used on the 904.
The result was a car that weighed 580 kg, approximately 250 lb (113 kg) lighter than the 904/6 (the 6-cylinder 904). The engine regularly fitted was the 901/20 6-cylinder lightweight racing engine with 220 hp and carburetors, although some examples that were raced by the factory team received fuel injected or 8-cylinder engines, especially in hillclimbing events where Porsche competed with Ferrari Dinos for the European championship.
Unlike previous racing Porsches, the 906’s body was tested in a wind tunnel, resulting in a top speed of 280 km/h at Le Mans, quite fast for a 2-liter engine car. It shows already a close resemblance to future Porsche racing cars. As in the Mercedes-Benz 300SL, Gull-wing doors were fitted, and the engine at the rear was covered with a large plexiglas cover.
In its debut in the 1966 24 Hours of Daytona, the Carrera 6 could finish 6th overall, and win its class against Ferrari Dino 206 Ps. At the 12 Hours of Sebring, Hans Herrmann/Gerhard Mitter finished forth overall and won the class, as at the 1000 km of Monza.
The 1000 km at Spa were disappointing, as were the 1000 km Nürburgring were the Dinos were only beaten by the Chevrolet-V8-powered Chaparral. A privately entered 906 secured an overall victory at the 1966 Targa Florio when the factory cars failed.
At the 24 Hours of Le Mans, the Ford GT40 won 1-2-3 ahead of the Porsches which could beat all of the previously dominating V12 -Ferrari Ps for the first time.
In order to save money, spare suspensions produced in advance for a possible new series of Porsche 904 had to be used for the 906, along with big 15 inch wheels. Yet, Formula One used lighter 13 inch wheels, and Porsche had already used Team Lotus suspension parts in earlier years. The wheels were bolted on with 5 nuts as in a road car, which cost time in pitstops compared to a single central nut.
To take advantage of the lighter wheels and F1 tyres, the Porsche 910 was developed and entered in mid-season of 1966, starting with the hillclimb from Sierre to Crans-Montana in Switzerland.