Porsche is one of the most famous sports car manufacturers in the history of motoring. The German brand has provided gearheads with some of the most focused and over-engineered models in the performance sector, the brand being famous for chipping away at its designs to extract every last drop of potential from them.The best example of this is its iconic 911 model, which it has continually developed since it first made its debut back in 1964. While the engineering underneath is largely unrecognizable in its 2024 examples compared to the first edition 60 years ago, the exterior still exudes the same charm as its grandfather.Alongside its bread-and-butter versions, Porsche has also produced its fair share of unicorns. HotCars therefore decided to find the rarest production Porsche model ever made. Special Convertible 911 Turbo Is The Rarest Porsche Of Them All RM Sotheby's1993 Porsche 911 964 Turbo Cabriolet SpecsThe year 1989 was a pivotal one in the history of the 911. In celebration of the model's 25th birthday, Porsche wanted to revolutionize it to prepare the venerable sports car for the future. The 911 had remained largely the same during the first couple of decades of its production, with the familiar looks being combined with a rear-mounted, air-cooled flat-six engine that powered the rear wheels.One of the biggest changes was the advent of the Turbo model, which was unleashed in 1975. The 260-hp weapon could hit 60 mph in just 5.4 seconds, which in 1975 was a performance expected from a supercar rather than a usable sports car. Porsche wanted to take a similar step forward with the new version of the car, which would be dubbed the 964.RM Sotheby's The new 911 was made up of 85% new parts when compared to its predecessor, but as was tradition, was available in coupe, targa, and cabriolet flavors. Arguably the biggest change with the 964 was that it had all-wheel drive, a first for the 911 model. Called the Carrera 4, the 964 was launched exclusively with this layout in 1989.The more traditional rear-wheel drive Carrera 2 followed a year later, in 1990, while the Turbo model joined the party in 1991. Even though the base Turbo was pretty potent, some tuned examples could make even this look pedestrian.RM Sotheby's The rarest Porsche ever produced was an interesting mix of these two variants, which was cooked up by the Porsche Exclusive operation. Located in Weissach, Germany, the shop dealt with special orders from extremely well-off customers. It worked like the RPO program run by Chevrolet.A total of six collectible 964 Carrera 2 Carbrios were taken off the Porsche production line and transported to Porsche Exclusive for their special operations.c The 911 Turbo Cabriolet Was Specially Created For A Half-Dozen Lucky Drivers RM Sotheby's The 964 Turbo of the era wasn't available as a cabriolet, so the Carrera 2s had their base 3.6-liter flat-six engines removed. In their place was the turbocharged 3.3-liter flat six used in the Turbo used between 1990 and 1993, the engine coming from the previous generation 930 model. Porsche elected not to develop a turbo version of the new 3.6 initially, so it used the proven 3.3 unit instead.The turbocharged 3.6 flat-six engine, which Porsche stuck with due to its effect on the handling of its models, eventually made its debut in 1993. The 3.3-liter unit remained in the back of the special Carrera 2 Cabrios. All six had the X33 S package, which meant the engines were tuned to within an inch of their life to produce 355 hp, up from the standard 320-hp figure. They even looked the part, as the Carrera 2s were fitted with the Turbo-look package from factory.This included widened bodywork, new brakes and wheels, upgraded suspension, and the striking whale-tail spoiler to make them look like Turbo models. With the addition of the 3.3-liter turbo unit, they could now walk the walk as well as talk the talk. Three of the vehicles were built as left-hand drives for the German market, while the other three were right-hand drives. Each 964 Turbo Cabrio Was Unique RM Sotheby'sAccording to RM Sothebys, two of these went to the United Kingdom, while the other traveled down under to Australia. All six featured different specifications depending on what their owner desired, with one example being finished in Amethyst Pearl Metallic and shipped to the UK. This version of the ultra-rare model was sold by RM Sotheby's back in 2018.It's the only one of the six featuring the color, with the exterior twinned to a cashmere leather interior. This car was equipped with a wheel-spin-mitigating limited-slip differential, air conditioning, a premium Sony stereo system, and a fully-powered fabric drop-top. The 3.3-liter engine is complimented by a five-speed manual gearbox, big ventilated and cross-drilled disc brakes, beefed-up anti-roll bars, as well as uprated struts and half-shafts.The 964 Turbo Cabriolet is a true unicorn in the sports car world, so any interested gearheads had better snap them up when the opportunity arises. You'd better have deep pockets though, as the example held by RM Sotheby's sold for a commanding $487,503. Maybe it's time to put that credit card to good use. Porsche Built A One-Off 993 20 Years After It Went Out Of Production Porsche2018 Porsche 911 993 Turbo SpecsWhile the 964 Turbo Cabrio is the rarest production Porsche ever constructed, there are some rarer vehicles from the brand that were never available from the showroom. One such example was 'Project Gold', a vehicle built in 2018 by the talented team at Porsche Classic. The idea was to build a bespoke version of the 993 Turbo, which went out of production back in 1998.A new chassis and bodyshell using the same design as the original were built, with the Porsche Classic team taking advantage of the brand's heritage parts service to source all the right bits to create a brand-new 993 built to 1998 spec. A new twin-turbo 3.6-liter flat-six was introduced to the special vehicle, while the body was out through the same corrosion protection process as its modern cousins.The original-spec six-speed manual transmission and all-wheel drive system were also sourced from Porsche's parts service, the 450-hp monster promising every bit as much performance as the original. Given the improvement in manufacturing processes seen in the automotive industry in the 20 years or so between the standard run 993s and Project Gold, it will likely prove more reliable over time.It took the team a year and a half to complete the project, with the idea of auctioning it off for charity when it was finished. Its 'Project Gold' name comes from the Golden Yellow Metallic color it was finished in, one inspired by the 991 Exclusive Series released in 2018.The car was eventually auctioned off by RM Sotheby's at the Porsche Experience Atlanta facility in October 2018. It ended up selling for $2.96 million, with the net proceeds going to Porsche's non-profit Ferry Foundation charity. As 993s go, Project Gold is not only the rarest but arguably the coolest too.