ACL GTC Porsche 904/6

Today the 904 or Carrera GTS remains as one of the finest and most successful Porsches ever constructed. It kickstarted a program of racing cars, that would eventually result in the all conquering 917. It also holds a unique spot in the manufacturer's history as the last dual-purpose sportscar Porsche ever built.

The radical 904 was the first Porsche to use a ladder-type frame – spaceframe construction was too expensive for what was, in essence, a production car – and glassfibre body, with the manufacturing turned over to Heinkel Flugzeugwerke in Speyer. It was novel in that the rather unevenly sprayed glassfibre body was bonded directly to the steel chassis to add stiffness, the upshot being that it was more rigid than the previous spaceframe cars. Also, the 904 was commendably light at 675kg, its 2mm-thick (give or take) glassfibre shell weighing only 85kg. The shark nose helped give a drag coefficient of 0.34, low for the time, and a top speed of 160mph, after reaching 60mph in 5.5 seconds from rest.

Three prototypes were constructed and tested heavily in the fall of 1963. After various modifications were carried through, the car was first shown to public late in November. Internally it was known as the '904', but it was marketed to the public as the 'Carrera GTS'. Today it's commonly referred to as the 904. Within two weeks all but 21 of the 90 examples available for the public were spoken for. Production started soon after in a completely new factory, constructed to produce the new 901/911 model. By April of 1964 enough examples were constructed to homologate the 904 as a GT.

Although it took until April for the cars to be homologated, the cars were already entered in various races. At Sebring the Lake Underwood and Briggs Cunningham driven 904 finished 9th overall and 1st in the prototype class. This was the start of a highly successful racing career, with overall victory in the Targa Florio and many class victories in races like the 24 Hours of Le Mans. Underlining the car's versatility was a second place finish in the snow covered 1965 Rallye Monte Carlo.