My brother-in-law has the Cayenne S and I have driven it several times. To me it definately feels heavy like I was towing a boat! It has more of a luxury feel to it with a smooth ride. My X5 however has much more of a sporty feel to it. I have 20" wheels on mine which make a big difference in the ride & handling but still, mine feels much more responsive to the pedal. I notice this every time I drive his Cayenne and get back into my truck.

Sure the Cayenne has 340HP but people forget it is about 600lbs heavier than the X5. It needs that extra horse just to pull that extra weight when you compare the HP to weight ratio. At the end of the day, both vehicles are neck to neck comparing 0-60 at 6.9sec.

So it comes down to the tires, wheels, etc. and of course the driver. I would smoke any Cayenne S with my 4.4i ... and he would burn half a tank of gas extra just trying to keep up with me! The Cayenne has amongst the worst gas mileage along with the Range Rover.