The terms “race car for the road” and “prototype” are often overused to the point of losing their significance. However, in 1992, Porsche gave these words true substance with the 964-based Turbo S, a street-legal evolution of its IMSA championship-winning race car. Motorcar Journal had the rare opportunity to drive the original prototype from the Porsche Museum in Stuttgart on an unforgettable two-day journey through the Black Forest.

Street Racer

The Porsche 911 has always been a quintessential sports car, and for those seeking the most extreme version, the GT3 RS is the current benchmark. However, today’s 911 Turbo S combines even better performance with additional comfort, offering unrivalled everyday usability. Things were very different in the 1970s though, when Porsche, alongside BMW, pioneered the use of turbocharging in motorsport.

In 1975, Porsche launched the first-generation 911 Turbo, internally known as the 930. It served as the homologation model for the 934, which was a race car that entered the International Group 4 Sports Car Championship in 1976. This 934 laid the groundwork for the faster and more extreme 935, built for Group 5 competition.

In order to compete with the 934, homologation rules from the International Motorsport Federation (FIA) required the production of 400 road cars within 24 months. Few could have predicted that the 911 Turbo would ultimately find more than 2,800 enthusiastic buyers. In 1978 Porsche followed up with an upgraded version featuring a 3.3-liter flat-six producing 300 hp, a significant increase over the original 3.0-liter’s 260 hp. This 3.3-liter Turbo proved an even greater success, with nearly 19,000 units sold by the end of its production run in 1989.

No Turbo

The arrival of the Turbo was as historically significant as milestones like the introduction of water cooling on the 996 and the fully electric Taycan. By the late 1980s, the financial situation in Stuttgart had changed drastically, putting not only the future of the 911 Turbo at risk, but also the very survival of the 911 and even the entire brand. Porsche scrapped the initial plans to make the Turbo a standalone model called 965, which would be inspired by the 959. With the launch of the new 911 generation (964) in 1989, Porsche no longer had a Turbo in its lineup. It wasn’t until 1991 that a Turbo based on the 964 finally appeared. The failed development of the 965 Super Turbo had drained both budget and precious time, so the 964-based 911 Turbo received the 3.3-liter engine from its predecessor, albeit with some upgrades.

Leichtbau

When I received the key to the yellow Turbo S in the museum workshop by Porsche Heritage spokesperson Alexander Heidig, he warns, ‘Please be careful, this car is much more powerful and faster than most people expect. It’s a unique prototype, and we’d like to see it returned in this condition.’ As I leave the museum grounds, under the watchful eyes of visitors and factory staff, Alex’s words echo in my mind. At the same time, it strikes me how smoothly the Turbo S weaves through the busy traffic in Zuffenhausen.

With its chassis lowered by forty millimeters, the Turbo S feels significantly firmer than the regular Turbo, more akin to the Carrera RS. Weighing nearly 200 kilograms less, the nickname Leichtbau is fitting, because it translates to “light built” from German. While more power only affects acceleration, a reduced weight offers benefits in acceleration, braking, and cornering, enhancing the car’s overall handling and agility. In heavy city traffic the extra-powerful turbo engine does not reveal any surprises, but you sense its slumbering potential as the tachometer needle approaches 4,000 rpm.

What makes the Turbo S so special is the combination of factors that were previously available only separately. A lightweight 911 existed in the form of the Carrera RS, but it had a naturally aspirated 3.6-liter flat-six with a modest 260 hp. The 911 Turbo produced 320 hp – and with the so-called Werksleistungssteigerung (code X33) it reached 355 hp – but it weighed a hefty 1,715 kilograms. The idea of combining the best of both worlds emerged in late 1991 within the Sonderwunsch department, inspired by a championship win in a new class within the American IMSA Series.

Brumos Racing

In 1991, the International Motor Sports Association (IMSA) introduced the Bridgestone Potenza Supercar Championship in the United States. This series was designed as a crowd-warming event before the GT Championship races. The Supercar Championship featured sports cars such as the Chevrolet Corvette, Nissan 300ZX, Lotus Esprit, and Porsche 911 Turbo. These cars were required to adhere closely to production specifications and race on Bridgestone Potenza RE-71 street tires. For dry conditions, the tread could be shaved down to semi-slicks, but in the rain, full tread depth was mandatory.

Brumos Racing from Florida fielded two 911 Turbos, with Hurley Haywood as their primary driver. Multiple drivers, including Hans-Joachim Stuck, shared the second car. Haywood claimed the 1991 championship with car number 59, earning Porsche the constructor’s title. This victory was so well received in Stuttgart that Porsche decided to release a special edition of the 911 Turbo to celebrate the title.

Limited Edition

By January 1992, Rolf Sprenger, head of the then Sonderwunsch-Programm (later Porsche Exclusive Manufaktur), sent a memo to colleagues and stakeholders announcing plans for a model referred to as the 911 Turbo “RS” (Leichtbau). This special version was already approved, with key features outlined: reduced weight, improved performance, a no-compromise sports suspension, and visual modifications such as a new rear spoiler, cooling vents in the sides, and special wheels. All cars would be delivered as road cars and sold by dealers with a set commission of 10,000 Deutschmarks, although delivery could also take place at Zuffenhausen. Customers were required to make a 30,000 DM down payment, with the final price set to no more than 300,000 DM.

At the 62nd Geneva Motor Show in March, Porsche unveiled the lightweight 911 Turbo, which, thanks to extensive modifications, produced 381 hp and 490 Nm, while weighing nearly 190 kg less than the production model.

Shortly after the debut, Jürgen Pippig from Porsche’s motorsport division sent an internal memo stating that potential customers were so fascinated by the new lightweight concept that Porsche decided to produce a limited run of between 20 and 50 units. A subsequent press release confirmed the car would be officially named the 911 Turbo S, delivering nearly the same performance as the legendary 959. It was specifically aimed at amateur racing (club sport events) and collectors of exclusive cars. The price was set at 295,000 DM, translating to around 300,000 Euro in today’s money.

Unfiltered

As we reach the scenic Schwarzwald, with its beautiful, rolling, and mostly deserted roads, the Turbo S can finally reveal its true nature, allowing us to experience how radically the rear-mounted six-cylinder has been transformed. With features such as new cylinder heads, polished intake and exhaust ports, sharper camshafts, and adjusted valve timing, the engine feels more powerful than the standard Turbo, and even the X33 factory-tuned variant.

The lowered and stiffer suspension, combined with the absence of any comfort features, creates a raw, pure, and unfiltered experience. The docile character of the engine shifts abruptly around 4,000 rpm, and the six-cylinder starts to roar, with acceleration proving even more spectacular than expected. The linear character of a Carrera RS, or even the RS 3.8, fades in comparison as the turbocharger spools up and 381 hp is unleashed to the rear wheels.

Turbo RS

Thanks to the larger 18-inch Speedline wheels and 265 rear tires, there’s an impressive amount of grip. Accelerating flat-out into fourth gear transforms the surroundings into a green tunnel, and hard braking is the only appropriate response with a corner looming in the distance. The Turbo S also decelerates impressively, with its low weight coming into play once again.

The extent of the weight-saving measures becomes clear when we take a closer look at some details during the photoshoot. The side and rear windows are made of thinner glass, and fiberglass-reinforced carbon composite is used for the bonnet, rear spoiler, and doors. The seats have been replaced with lightweight Recaros, and black carpeting with a large yellow Turbo logo took the place of the rear seats. Features like electric windows, central door locking, and air conditioning were deemed too heavy, as were soundproofing materials and even underbody protection. At just 1,280 kg, the Turbo S weighs a full 190 kg less than the standard 911 Turbo, making the initially proposed name Turbo RS Leichtbau entirely justified.

Explosive

Despite the immense grip from the rear wheels and the confidence the chassis provides, we remain mindful of the typical tail-heavy nature that older 911s are known for, especially in combination with a turbo lag. Accelerating out of a corner at high speed doesn’t happen with a heavy foot on the throttle, but with precision and a careful eye on the tachometer. As long as you keep the explosive character around 4,000 rpm in mind, there’s little to fear from the Turbo S.

After a few hours behind the wheel, confidence has grown to the point where I regularly charge through the twisty forest roads at blistering speeds, all while the atmosphere inside the car feels as if we’re casually cruising through the countryside. The engine sound becomes the key indicator of just how fast we’re going. With the windows cracked—because there’s no air conditioning—you hear not only the raw shriek of the six-cylinder at over 6,000 rpm, but also the loud echoes bouncing off the rock walls, along with the irregular pops in the exhaust when downshifting while blipping the throttle. The shifting itself is tight and precise, as this example from the factory collection has barely 4,000 kilometers on the clock, making it virtually new.

Most Desirable

Where the Turbo once was a Sondermodel and the rest of the lineup had to make do without forced induction, nearly every Porsche nowadays features a turbocharged engine, making naturally aspirated engines the rarity. Still, we dare to claim that this Turbo S is one of the most impressive and desirable 911 variants ever made. It is also the last Turbo with rear-wheel drive, which enhances the unfiltered driving experience and the raw sensation of speed. There is no other 911 that connects the driver to the experience quite like this one, offering an abundance of that analog thrill that is harder and harder to find these days.

Of course, there are countless 911s that are faster and even better in various ways, but none are more entertaining. A notable detail is that the 86 “regular” Leichtbau units have a market value of over 1.5 million euros, making this prototype race champion for the road both unique and priceless.