With the demise of the Group 5 class and the introduction of Group C, many teams—including Joest Racing—decided to build a purpose-built car. Reinhold Joest began with the Porsche 936 model as a base.
In the winter of 1981/82, Joest created a completely new car according to his own vision, closely adhering to the Group C regulations and loosely inspired by the Porsche factory design. The chassis was a spaceframe, similar to the 936 Spyder, but modified with a roof structure. The wheels, suspension, and transmission were the same as the 936/77. The engine was a 2.6-liter engine modified by Joest, while the bodywork was built by Ekkehard Zimmermann's DP company—known for its collaborations with Kremer.
The Porsche 936C JR-005 made its Interserie debut at the Nürburgring, finishing an impressive third overall. The car was then entered in the World Endurance Championship and several DRM rounds.
After a disqualification at Monza, the JR-005 took 3rd place in the 6 Hours of Silverstone (in Belga livery) and another 3rd place in the 1000 km of Mugello (official Joest Racing entry), where it even finished 1st in Group C. This was followed by a 4th place finish in the 6 Hours of Spa (Belga) and a strong finish in the 9 Hours of Kyalami with drivers Hans Heyer, Volkert Merl, and Dieter Schornstein.
The year began with two DRM races for Volkert Merl, followed by entries in the 1000 km of Silverstone and the 24 Hours of Le Mans with Jean-Michel Martin, Philippe Martin, and Marc Duez. Unfortunately, both races ended in DNFs. The car was then given a striking yellow-and-black New Man livery for DRM races and the Spa 1000 km. Later, in Warsteiner livery, it finished 7th in the 9 Hours of Kyalami with Leopold von Bayern, Siegfried Brunn, and Klaus Grögor.
Ernst Schuster brought the car back to action in the 360 ??km of Monza and a Supercup race. After a 17th-place finish in the 1000 km of Silverstone, the JR-005 returned to Le Mans. It finished second in the Test Sprint, and surprised everyone in the 24 Hours race: flawless driving, only 25 pit stops for fuel, brake pads, and tires, and an impressive 6th-place finish overall. Several more Supercup races followed.
For its very last race, Schuster took the car to the 500 km of Kyalami.
