The 908 was Porsche's first sports car prototype designed around the maximum 3-litre engine displacement permitted under the post-1968 Group 6 prototype rules. The series evolved through several body configurations: the 908 LH coupe of 1968, the lighter open 908/02 spyder of 1969, and the substantially revised 908/03 introduced in 1970. Where the 908/02 had been a competent all-rounder, the 908/03 was built on a philosophy borrowed from the Porsche 909 hillclimb car — extreme lightness and a very short wheelbase to maximise agility. The engine was the 2,990 cc flat-eight producing 370 PS (272 kW), carried over from the 908/02 but in a substantially reduced package.
Porsche's strategy from 1970 was deliberate two-car specialisation: the 917K for fast, power-dependent circuits such as Daytona, Spa, and Monza; the 908/03 for the Targa Florio and the Nürburgring, where typical speeds were roughly half the 917LH's maximum of 390 km/h at Le Mans.
The 908/03 made its competitive debut in May 1970 and the very same chassis, numbered 008, won both its target races. At the Targa Florio, the car was entered by JW Automotive, painted in Gulf blue with red arrows as car number 12, driven by Jo Siffert and Brian Redman to victory. Further 908/03 entries finished second, fourth, and fifth in the same race. Four weeks later at the Nürburgring 1000 km, chassis 008 was entered by Porsche Salzburg, now in plain white, with Vic Elford and Kurt Ahrens at the wheel. After the two leading JW cars crashed out, Elford and Ahrens led a 1-2 finish for the 908/03, with four more 908/02 cars filling positions four through seven behind them.
For 1971, vertical fins were added to the rear of the 908/03 — mirroring the aerodynamic treatment of the 1971 917K — along with larger roll bars. The car returned to the Targa Florio and the Nürburgring as the factory's nominated cars for those events, but with less preparation than usual given Porsche's dominant position in the championship by that point.
At the 1971 Targa Florio, all three entered 908/03s ultimately crashed. The two JW-entered cars were eliminated on the first lap, with Brian Redman badly injured in a fiery accident. Vic Elford, driving the Martini-entered chassis 008, managed to set the fastest lap but also crashed late in the race and was classified 39th. Alfa Romeo won the event, with Nino Vaccarella leading a 1-2 for the Tipo 33.
At the 1971 Nürburgring 1000 km, two badly damaged 908/03s had to be repaired following the Targa. Despite arriving late at a freshly resurfaced circuit, Vic Elford in chassis 008 hunted down the faster Ferrari 312PB and Alfa Romeo competition through attrition. The Ferrari led by nine seconds in qualifying but suffered engine troubles in the race, as did the leading Alfa. Elford brought the 908/03 home to win, completing a 1-2-3 finish for the works 908/03s, with two Alfa Romeo 33s and a private 917K completing the top six.
New minimum weight regulations for 1972 negated the 908/03's principal advantage, and Porsche sold the factory cars to customer teams. The chassis continued racing throughout the 1970s, initially with the original 370 PS flat-eight and later retrofitted with 2,140 cc turbocharged flat-six engines derived from the Porsche 934 GT car, which produced over 500 horsepower. A 908/80 variant — later revealed to be an actual Porsche 936 chassis — finished second at the 1980 24 Hours of Le Mans driven by Reinhold Joest and Jacky Ickx. The 908 won the 1000 km Nürburgring in three different decades, with victories from 1968 to 1971 and again in 1980 using turbocharging for its final factory-associated win.
The 908/03 demonstrated that a purpose-built, ultra-light prototype could neutralise the raw power advantage of much larger cars on circuits that rewarded agility and driver feedback over outright speed. Its chassis number 008 winning three of the four major twisty-circuit races in 1970 and 1971 is one of the most concentrated records of circuit-specific success in World Sportscar Championship history. Some 908s continue to race in classic endurance series such as Classic Endurance Racing.