They've been locked behind closed doors for decades, but now Porsche is revealing a number of very special potentially priceless vehicles from 1970s, 80s, and 90s at the Porsche Museum in Stuttgart, Germany.
The exhibition, titled 'Project: Top Secret', kicked off on September 17, 2014, and runs until January 11, 2015, displaying 16 showpiece vehicles that Porsche enthusiasts of the era would have given their left kidney to see.
Admission to the Top Secret exhibition is €8, with camouflaged prototypes and concept cars that have never been shown before, spanning five decades, on display. The FLA sustainable car research project, for example, was a concept car answer to the energy crisis in 1973, designed to use very little fuel.
Other rare models from the era include the Porsche 924 world record setter and the Type 995 experimental passenger car, and the 1980s feature a number of big names too, like a 928 Cabriolet, Porsche 959 aerodynamic prototype and even the Roadster Type 984 concept car which has never been publicly shown before.
Fans will also be interested in the seeing a prototype of the Porsche 965 high-performance sports car which is being shown for the first time ever, its water-cooled V8 mounted in the rear of the car.
There's also a number of unrealised projects from the 1990s, including the original Panamera, a four-door Porsche 989 'family sports car', and a cool prototype car based on a Porsche 911 Targa Type 964 that was used to test the idea of a Boxster mid-engined sports car.
Closer to the modern era is a camouflaged prototype of the Porsche Panamera and a 'rolling chassis' of the 918 Spyder hybrid supercar.
If you're in Germany between September and January, it'll be well worth checking out for any car buffs. There's even some special family events between 2:00 and 5:00 p.m. on certain Sundays (Sept. 28, Oct. 19, Nov. 16, Dec. 14, Dec. 28 Jan. 4) which include scavenger hunts and the chance to camouflage a 918 Spyder model. Check out the website for more details.