i drove the 2011 cayenne S, cayenne turbo and it seriously does destroy the x5 in overall performance. i love the new modernized interiors. (i have a 2006 C2S). that being said, i walked away thinking i dont need to pay all that extra money for the performance in a cayenne S when all i want is the utility that an x5 would provide me (a nice, easy to drive, not too expensive suv)...
i sat in the cayenne turbo as a pro-driver took me on 2 hot laps at fontana.... it was AWESOME and something that an X5 5.0 would not be capable of.