Sammy:
They are providing the right product to a specific market that allows them to maintain their profit margins (granted I don't even know if this is true or not so if you have some stats that would be awesome!).
I just found this:
http://en.wikipedia.org/wiki/Porsche :
"The company has been highly successful in recent times, and indeed claims to be the most profitable car company in the world (in terms of profit margin per unit sold; its absolute profits would be dwarfed by Toyota) [2]."
Here's another quote from it:
"Porsche was awarded the 2006 J.D. Power award for highest initial quality of automobile brands."
Now Wikipedia may be as good as a post in a forum (lack of sources, citations, etc.) but I've read about the highest profit margin claim elsewhere and seems that it's widely accepted.
Z.