I have a 2010 957 base. 86K on the clock. Less is more with these cars. Mine has the VR6 engine, strut suspension and not a lot of bells and whistles. it's rock solid, handles like a sports car even at 5000+ pounds. fun to drive. You can buy them stupid cheap right now, but keep in mind it's still a Porsche. So when it breaks, it's very expensive to fix. The desirable ones are pre 2011. They share a lot of parts with the VW Toureg and Audi Q7 so if your DIY always compare prices on the same part for all three models.
My only complaint is even with the 6 cylinder engine it only get 16 MPG and drinks premium fuel.
