It takes bold ideas to stay at the top of the sports car world. That's why Porsche designers never stop. Some designs end up as production models while most others meet an unfortunate fate. But the Porsche museum has chosen to hang on to the wildest examples, and they compiled them in a YouTube video uploaded this morning.

In the latest installment of Porsche Top 5, we get to see a few very unusual and intriguing top five secret Porsche prototypes.

5. Porsche 984 - Their goal was to increase performance by cutting weight and aerodynamic resistance. Tipping the scales at 1,940 lbs, this 133 horsepower featherweight has a top speed of 136 mph

4. Porsche Cayenne Cabrio - The company had a lot riding on the success of the Cayenne, so nothing was off-limits when it came to bold ideas. It did influence the evolution of the 911 Targa thanks to the integrated rear roll bar.

3. Porsche 911 Carrera 3.2 Speedster ClubSport - This 1987 example is a faithful successor to the early 550K Spyder thanks to a 1-piece tonneau covering the cockpit. Powered by their 3.2L flat-six, it has 231 horsepower and a top speed of 152 mph.

2. Porsche Panamericana - This was a birthday president for Ferry Porsche. He turned 80 years old in 1989, and this one surely helped him remember the glory days of racing in the brutal Central American rally. Check out the family crest engraved in the tire treads! It has 250 horsepower and a top speed of 130 mph

1.Porsche 918 Spyder Rolling Chassis - Looking more like Terminator than a supercar. the 918 Rolling Chassis was built in 2012 to show the press how the hybrid system would be integrated. It offered a combined 550 horsepower and it helped make the 918 a hypercar for the ages.