[Perfectlap]

I don't think the Boxster is different than any other Porsche.
Its simple economics, supply and demmand. Porsche has produced more cars in the last 7 years then they have at any point in their history. I've seen MINT condition 2002 911 Turbo's selling in the mid $50K's , a depreciation skirting the 50% mark after less than five years...crazy, that was considered an exotic at one point and now $50K won't buy you a CaymanS, and X5 or a lemon Mercedes.
All new Porsches are depcreciating faster than most of their owners have anticipated. But I have yet to see any data comparing Porsches to other luxury brands from Germany that would suggest that Porsche is depreciating a quicker clip than BMW or Mercs. If anything I would say that the improved reliabiltiy of Porsche is opening the door to a wider pool of buyers which helps a seller expand his target market.
Ask a Jaguar or Range Rover owner how quickly his 7 year old car is selling...