The revival of top-level international sportscar racing in the mid-1990s through the BPR Global GT Series — which subsequently developed into the FIA GT Championship — gave Porsche a route back into endurance racing. The GT1 category that the series featured attracted manufacturers building highly modified road cars including the McLaren F1 and the Ferrari F40.
Porsche initially modified the 993-generation GT2 into an EVO version and entered it as a GT1 contender, but this proved uncompetitive against the purpose-built rivals. Porsche therefore developed an entirely new car, the 911 GT1, which used the 911 name and shared its front and rear headlamps with the production car but was otherwise a distinct machine. The frontal chassis was based on the 993-generation 911 structure, while the rear subframe was derived from the 962C Group C prototype.
The car used a water-cooled, twin-turbocharged 3,164 cc (3.2-litre) flat-six engine with four valves per cylinder, fed by Bosch Motronic 5.2 fuel injection and mounted longitudinally in a rear mid-engine, rear-wheel-drive configuration — fundamentally different from the rear-engine layout of any production 911. Power output was approximately 600 PS (441 kW; 592 hp). This contrasted with the contemporary 993 GT2, Porsche's highest-performance road car at the time, which still used an air-cooled engine with two valves per cylinder.
The 911 GT1 made its racing debut in the BPR Global GT Series at the Brands Hatch 4 Hours, where Hans-Joachim Stuck and Thierry Boutsen won. However, the entry was classed as invitational, making it ineligible for points. The factory team subsequently won at Spa-Francorchamps, and Ralf Kelleners and Emmanuel Collard took a further victory at Zhuhai. During the 1996 24 Hours of Le Mans, the 911 GT1 was timed at exactly 330 km/h on the Mulsanne Straight during practice sessions.
Towards the end of the 1996 season, Porsche revised the car for 1997 to produce the 911 GT1 Evo. The front bodywork was updated and incorporated headlamps that previewed the appearance of the incoming water-cooled 996-generation 911 production car. The revised aerodynamic package made the 1997 car considerably faster than the 1996 version in acceleration terms. The engine specification was unchanged.
At Le Mans in 1997 the works cars led the race but did not finish the distance. A privately entered 1996-specification GT1 managed fifth overall and third in the GT1 class.
For 1998, Porsche designed an entirely new car, the 911 GT1-98. It was developed to match the also-new Toyota GT-One and Mercedes-Benz CLK LM, and its bodywork had moved further from the 911 road car aesthetic toward traditional sportscar prototype styling. A sequential gearbox was installed to reduce gearchange time, and engine management moved to a TAG Electronic Systems TAG 3.8 ECU.
During the 1998 FIA International GT season proper, the 911 GT1-98 was disadvantaged by air-restrictor rules that proved unfavourable to its turbocharged engine relative to the Mercedes-Benz's naturally aspirated V8. The Mercedes tyre supplier Bridgestone was also considered superior during the season.
At the 1998 24 Hours of Le Mans, however, the conditions aligned differently. The BMW V12 LM retired with wheel bearing failure. The Mercedes CLK LM cars suffered oil pump problems with their replacement V8 engines. The Toyota GT-One — considered the fastest car — encountered gearbox reliability problems that prevented it from completing the race distance. The 911 GT1-98, despite being slower in outright pace than the Toyota and Mercedes, finished both first and second overall thanks to reliability, giving Porsche its record-breaking sixteenth overall victory at Le Mans — more than any other manufacturer at that time.
FIA GT1 regulations required that 25 road-legal examples of any GT1 car be produced for homologation purposes. Porsche developed two prototype road cars, the first of which was delivered to the German Federal Ministry of Transport for compliance testing in early 1996. The production run of approximately 20 units — dubbed the 911 GT1 Straßenversion — was built in 1997 and featured 996-style front headlights. Most were finished in Arctic Silver or Fern White, with three examples in individual colours.
The road car's engine was de-tuned to meet European emissions legislation but still produced 400 kW (544 PS; 536 hp) at 7,000 rpm and 600 Nm of torque at 4,250 rpm. Independent testing recorded 0 to 100 km/h in 3.9 seconds and a top speed of 308 km/h (191 mph).
A single 911 GT1-98 Straßenversion was built in 1998 to satisfy homologation requirements for the revised racing car.
The 911 GT1 programme produced one of the most unusual cars to carry Porsche's name: a 911 in name and headlamp design only, otherwise a bespoke prototype built around racing technology inherited from the 962C. Its 1998 Le Mans victory was Porsche's sixteenth overall win and came in unusual circumstances — claiming victory through reliability against faster but unreliable opposition. The car remains one of the most sought-after Porsche collectibles, with the Straßenversion among the rarest of any homologation road car built to satisfy motorsport regulations.