In both cases, Evolution versions could then be introduced to homologate more extreme competition models. Group C meanwhile was for out-and-out sports racing cars that bore little resemblance to anything you'd find on the road. For this category, there were no production requirements. Porsche had absolutely dominated the Group 5 era with the legendary 935, so they more than anyone else had most to lose. To ensure their enviable winning record continued, Porsche launched the 956 and later, the 962. Like their illustrious forebears, these works and customer run prototypes were normally the class of any field. Unsurprisingly, Porsche went on to dominate the eighties in much the same way as they had before. In addition to the Group C programme, Porsche also built a handful of 911 Turbo's for Group B. Manufactured between 1982 and '83, they were most notably pitched against BMW's M1.

Group B rules stipulated that relatively few modifications from standard were initially permitted. Consequently, the suspension, brakes, bodywork and engine were largely identical to the stock 3.3-litre Turbo. Upgrades included adjustable Bilstein dampers and heavy-duty torsion bars of 22mm and 27.5mm front / rear (compared to 19mm and 26mm respectively). There were also thicker anti-roll bars of 22mm up front and 18mm at the back (the latter being adjustable). Stock 917-style brakes from the production car were used and the wheels weren't allowed to protrude wider than the standard bodywork. Cross-spoke BBS rims were adopted, the fronts being 9.5-inches wide (up from seven) whilst the rears rose from nine to eleven-inches.

Relatively few modifications were made to the engine, displacement remaining unchanged at 3299cc thanks to a bore and stroke of 95mm x 70.4mm respectively. Upgrades were restricted to 935 head gaskets, hot camshafts, a bigger engine intercooler and turbo boost increased from 0.8 to between 1 and 1.4 bar. Even with the standard Bosch K Jetronic injection, Gruppe B 930's were realising 364bhp at 5500rpm and producing 369lbs ft of torque at 4500rpm. The 935-style upright transmission was equipped with an oil pump and cooler and coupled to a clutch that was also imported from the old Group 5 machine. Externally, with the exception of a new competition oil cooler mounted in the front spoiler, these cars remained totally standard, right down to the bumpers. The front storage compartment housed a 100-litre fuel cell, a front-mounted oil cooler and aluminium strut brace. Inside they were stripped of every conceivable luxury, competition seats and a beefy alloy roll cage being installed. They were then brought back up to the minimum class weight limit by applying strategically positioned ballast. The minimum weight limit in Group B depended on a particular cars engine size and because the swept volume of Porsche's turbocharged 3.3 was equivalent to 5-litres, this meant the new car had to be no lighter than 1235kg. Porsche stripped the weight down to around 1150kg and then added the rest to make it legal.

Whereas a normal 930 would have taken 5.3 seconds to reach 100kmh, these factory hot rods could do it in 4.5. 0-160kmh came up in just 9.8 and 0-200 in a mere 15.8. Two cars were built for the 1982 season, chassis 93A 007 00171 for Georg Memminger and 930 970 00069 for Bernd Schiller. ‘93A' was a factory conversion of Memminger's 1980 930 road car. In 1982 it took World Manufacturers Championship wins at the Nurburgring, Spa and Mugello 1000km races. Meanwhile, 00171 was a regular in the German national series. Four more cars followed in 1983, one for Charles Ivey in the UK (winner at Le Mans and Brands Hatch), one for the Almeras brothers in France (third at Le Mans), one for Michel Lateste (fourth at Le Mans) and another for Edgar Doren (winner at the Nurburgring 1000km). Mid-way through 1983, these cars were permitted to adopt 935 brakes and they went on to win the inaugural Group B Championship by two points from BMW. In 1984 the tables were turned and BMW won comfortably, amassing almost twice as many points as the Porsche teams. By this time it was obvious there was little support for Group B and the category was ditched from the 1985 season.