Porsche Leichtbau: A History of Lightweight 911s

Leichtbau translates as lightweight construction or lightweight design. At Porsche it is less a model name than a method, applied whenever the company built a road car for competition or for drivers who wanted the nearest thing to one. The recipe has barely changed in six decades: thinner steel and glass, glass fibre, aluminium or carbon panels, and the removal of anything that does not help the car go, stop or turn. Rear seats, sound insulation, power steering and air conditioning have all been deleted. A lighter car needs less power for the same pace and asks less of its brakes and tyres.

The earliest clear 911 example is the 911 R, which Porsche describes as a road-homologated racing car. Its front lid, front wings, doors and bumpers were glass fibre reinforced plastic, the windscreen was thin 4 mm glass and the other windows were 2 mm Plexiglas. At 800 kg it was 230 kg lighter than a 911 S, and its 2.0-litre Type 901/22 engine made 210 hp at 8,000 rpm. Porsche built four prototypes and then just 19 cars: at an estimated 45,000 DM the R cost nearly twice as much as a 911 S, so selling the 500 needed for GT homologation was never realistic.

The Carrera RS 2.7 was a homologation car. Porsche needed 500 to qualify it for Group 4 Special GT racing, and demand took production to 1,580. Its 2.7-litre flat six made 210 PS, and thin sheet metal, thin glass and plastic parts cut weight, and the racing versions also lost their insulation. The Sport package, option M471, went further by deleting the rear seats, carpets, clock, coat hooks and armrests. It weighed 960 kg, 115 kg less than the Touring package, option M472, and it reached 100 km/h in 5.8 seconds. Porsche built 200 Sport cars and 1,308 Touring cars.

The car most often called the Leichtbau is the lightweight 911 Turbo S of 1992 and 1993. Rolf Sprenger, who had formally set up Porsche's Sonderwunsch, or special requests, department in 1978 and by then managed Porsche Exclusive, proposed it in a January 1992 memo, and a prototype was shown at Geneva that March. Built with Porsche Motorsport, it had a 3.3-litre engine raised to 381 PS, 61 PS more than the standard Turbo. Composite doors, front lid and rear spoiler, and the removal of power steering, air conditioning, radio, dual-mass flywheel and rear seats, saved 180 kg. Only 86 were built.

The same thinking runs through Porsche's later RS and GT cars. The 964 Carrera RS of 1992 had 260 bhp, thinner glass, a stripped interior and lower, stiffer suspension, and weighed about 150 kg less than the standard car; its aluminium bonnet and thin glass carried over to the Carrera Cup racer built on it. In 2016 Porsche revived the 911 R name for 991 cars with a carbon bonnet and wings, a magnesium roof, a plastic rear window and rear side windows and a six-speed manual gearbox, at 1,370 kg. The 2018 911 GT3 RS offered a Weissach package of extra carbon parts and optional magnesium wheels.

Porsches of this era are often modified, which usually reduces value, so originality matters as much as condition. Check the engine and chassis numbers match the identity labels and paperwork, and value documented history over low mileage. Some have been used on track, so check brake and suspension wear; on a 964 RS, confirm the correct magnesium wheels, and the scarce thin glass and aluminium bonnet. A 1973 RS can be MOT exempt and taxed as a historic vehicle; a 964 cannot yet. Classic And Retro Autos in Witton Gilbert offers a £65 plus VAT inspection of about an hour on the hoist.

Leichtbau is German for lightweight construction. Collectors use it most for the 86 lightweight 964 Turbo S cars of 1992 and 1993, but the same approach defines the 1967 911 R, the 1973 Carrera RS 2.7 Sport and later RS models: thinner materials, composite or aluminium panels and fewer comforts, all to cut weight and sharpen performance.

Porsche built 86. Management first authorised a run of 80 in May 1992, and the cars were made in 1992 and 1993 with a 381 PS version of the 3.3-litre turbocharged engine. They weighed 180 kg less than a standard 964 Turbo, helped by composite doors and front lid and the deletion of power steering, air conditioning and the rear seats.

The Sport, option M471, was the lightweight version: the rear seats, carpets, clock, coat hooks and armrests were removed, and it weighed 960 kg. The Touring, option M472, kept the 2.4 S interior trim and weighed 115 kg more. Of the 1,580 Carrera RS 2.7s built, 200 were Sport cars and 1,308 were Touring cars.

The 1967 911 R was a road-homologated racing car weighing 800 kg, and 19 production cars were made. In 2016 Porsche revived the name for a 991-based car with a carbon bonnet and wings, a magnesium roof, a plastic rear window and rear side windows and a six-speed manual gearbox, weighing 1,370 kg.