Now, prices for second-hand examples of the sports cars have risen so sharply, some experts are wondering whether the bubble is about to burst.
Prices for good cars are going through the roof, which is all the more remarkable since the latest version of the car is still on sale in showrooms 50 years after the original model was introduced.
Take the be-spoilered 959 version, which was built from 1986 until 1993, although only 300 examples were turned out.
Prices for this memorable classic have gone up by an amazing 629 per cent in the space of two years. Several are currently on sale in Germany priced between 1.19 and 1.25 million euros (US$1.39mil-1.46mil).
The 959 can be outrun by some modern sports cars, but it was billed on introduction as the world's fastest street-legal production car, with a top speed of 314 kilometres an hour.
"Prices will keep on climbing but probably not as steeply as they have done in the past," says Marius Brune of the Classic Data analyst company. His firm monitors the asking and sale prices of cherished cars. "Dealers are pushing the envelope to see what they can get.""These value gains show clearly that the market is not rational," comments German car gazette Autobild Klassik.
Further down the range, a 964RS costs around 180,000 euros, followed by 170,000 for a 911 Speedster. That is much more than the cost of a new Porsche 911 from the Stuttgart factory. One of these will set back an owner in Germany from 97,914 euros, albeit without extras.
Prices for the last of the air-cooled 911, codenamed 993, are taking off too. During 2013, these rose in value by an average of 20,000 euros and a good example will now fetch at least 60,000 euros.
The water-cooled 996 version has been a wallflower until recently and clean cars could be picked up in Germany for around 15,000 euros.
Experts believe the 996 is a burgeoning classic, and well-maintained examples are already beginning to creep up in price.
As for the current 911, figures from Germany's new-car registration office confirms that it is the most popular high-performance sports car in Germany even though the market itself is tiny.
A total of 5,173 new 911s were registered in Germany in the first seven months of this year.
