Is the Cayenne pre-registered? By that I mean has the dealer bought the car to boost their current yearly sales figures?
If so that means it will be a 2012 car and you will be shown as the second owner. This, combined with a reduction in length of warranty, could have implications at re-sale.
It really comes down to just how good the dealer's offer is bearing in mind the above factors....
Of course, if it's not pre-registered and the specification suits your requirements... then that's a different story..
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"Things turn out best for people who make the best of the way things turn out."