Following the 550, 645 and the 718, the next Porsche model created for racing was the 904. The homologation rules stipulated a minimum of 100 units and as there weren’t that many potential racing customers, the solution was a street legal car. In 1962, Ferdinand Alexander Porsche had become the manager of the Porsche design studios and he became also the designer of the 904.
In August 1963, the first prototype was tested. Following the unveil of the 901 on September 12 at the IAA Frankfurt Motor Show, around 10 weeks later, on November 26, the 904 was presented at the Solitude race track near Stuttgart. The 4-cylinder cars were shown - chassis 904-002, 003 and 004 (002 and 003 being the prototypes).
The first 904s were delivered on January 16-17, 1964 - chassis no. 012 and 013. They were also the first 904s to be signed up for a race - the SCCA Divisional Riverside race on February 2, 1964 (result unknown, so actual presence not confirmed - please inform if you know).
Like the Porsche 356 C was sold at the time as just a Porsche C, the type 904 was called as Porsche Carrera GTS and therefore didn't have the naming problem the 901 ran into in France (car model names with zero in the middle were somehow reserved for Peugeot).
While the 4-cylinder 904s were racing already, the 8-cylinder fuel-injected prototype (904-009) was tested on the Le Mans test day on April 19, 1964. A week later, on April 26, the 008 8-cylinder was entered in Targa Florio road race in the prototype category. Driven by Edgar Barth/Umberto Maglioli it was victorious in the prototype class, but because of an accident scored only 6th overall. Antonio Pucci/Colin Davis in a 4-cylinder 904-005 took the overall victory and were followed by Gianni Balzarini/Herbert Linge in a 4-cylinder 904-006.
May 31, 1964 Nürburgring 1000 km race saw a record number of 904s signed up - 19 cars! Not all arrived, but there were eight 904s among the first twelve places. Gerhard Koch/Ben Pon won the 2-litre GT class with chassis 904-055 and were 3rd overall after larger-engined Ferraris. The next important race was the Le Mans 24H in June. Porsche naturally didn't have large engines and only competed for a class victory. Despite the very small engines, Porsche had scored 4th overall in 1955 with the 1.5-litre 550 and 3rd in 1958 with the 1.6-litre 718. The best Porsche result in the 1964 Le Mans 24 hour race was 7th overall and a class victory for the 2-litre 904 driven by Robert Buchet/Guy Ligier of Team Auguste Veuillet (A.Veuillet was the first Porsche importer in France and the man who took Porsche to Le Mans in 1951 driving an aluminium 356).
The last cars with chassis number starting with '904-...' were delivered before the Tour de France road race in September 1964. In total 108 cars were made with chassis number '904-' including one 6-cylinder prototype and two 8-cylinder coupés. The first 'series production' 6-cylinder 904, chassis 906-001, was entered in Paris 1000 km on October 11, 1964, but it had to retire due to an accident. The 8-cylinder 904-009 scored 3rd driven by Edgar Barth/Colin Davis.
Although 904 was designed as a racing car with low 4.7"/12 cm ride height, two 904s were entered into the rallye to Monte Carlo in January 1965.
Although called the Rallye Automobile Monte-Carlo, it really was a rallye 'to' Monte Carlo as the start was given from different locations around Europe (until 1972 the event was held on public roads and was more about durability than speed). Start for the 1965 rallye was given in the following cities: January 15, 16:32 Stockholm, January 16, 03:26 London (GMT), 04:38 Warzaw, 06:21 Athens, 06:34 Minsk (Moscow time), 07:35 Lisbon, 11:12 Paris, 12:36 Frankfurt and 13:19 Monte-Carlo. Every starting point had different rallye-route. All Porsche drivers signed up to start from Frankfurt.
The route for the participants starting from Frankfurt took them to Nürburgring, Holland, Belgium, all the way to Rennes in north-west France and with zig-zag down to Monaco covering more than 4000 km. After six days the 904 driven by Eugen Bohringer and co-piloted by Rolf Wütherich scored second (Wütherich is known as James Dean's mechanic who survived the horrific 550 Spyder crash in 1955). The very same car, chassis 904-006, also had scored 2nd on the 1964 Targa Florio.
A few six-cylinder cars were built for the 1965 racing season and they had many differencies compared to the predecessors: centered fuel filler, side windows that moved vertically (like on regular cars), a bit smaller doors (third door size), “elephant ear” large air intakes, different engine cover etc. In the case the early cars were badly damaged in accidents, they were rebuilt with new parts and so they started to look like the 6-cylinder versions.
On the May 23, 1965 Nürburgring 1000 km race the 904/8 (chassis 904-009) driven by Jo Bonnier/Jochen Rindt scored 3rd overall and was victorious in the 2-litre prototype class.
On June 20, 1965, the best Le Mans result for the 904 is achieved: a 6-cylinder version becomes 2-litre prototype class winner and 4th overall driven by Herbert Linge/Peter Nöcker. They are followed by a 4-cylinder 904 driven by Gerhard Koch/Anton Fischhaber (5th overall and 2-litre GT-class winner).
All 904s came with 2-litre engines from the factory - either 4-, 8- or finally 6-cylinder. Generally the 4-cylinder cars had "904-" chassis numbers and the 6-cylinder cars had "906-" chassis numbers. It was no rule though as the first prototype chassis 904-001 had a 6-cylinder engine and the 8-cylinder coupés also had "904-" chassis numbers, while the 8 cylinder spyders had "906-" chassis numbers.
The last factory chassis for 4-cylinder car was 904-108.
As the 4-cylinder engines were high tech units which were not so easy to maintain, later many were replaced with 6-cylinder engines. Although such a request could be carried out by Porsche, these conversions were mainly done by independent garages and so the new engines were not only the 2-litre units, but later even up to 2.8-litre units that were originally made for the racing 911s.
At the 1966 Nürburgring 1000 km race, German TV channel ZDF had borrowed a 904 from Porsche to install a TV camera in the cockpit for live broadcast. The car was driven by Paul Frère/Rainer Günzler. Because of the mountaineous landscape, a helicopter followed the car and transmitted the received signal to the station in Nürburg from where it was sent to ZDF headquarters in Wiesbaden and then immediately broadcasted.
Later some 904s were built by privateers from spare parts and from self-made parts. The following made-up chassis numbers are known to exist: 904-109, -113, -115, -119, -126. Another fact worth to mention is that some of the cars around the globe have same chassis numbers. For example if after a crash a new chassis was ordered from the factory and the chassls number plate was transferred, the old chassis was shed aside with no further plans. But then came the times when 904 prices skyrocketed and the old crashed chassis were also woken alive and new number plates were fabricated with the same numbers. Because of the risen value of 904s even the totally crashed and burned-down cars have been restored.