I'm contemplating purchasing one of these within the week. The RR is more luxurious with better quality interior materials. Power is acceptable. The Cayenne has better driving dynamics, but I don't like the looks as much. I suspect reliability would be similar for both. The funny thing is much of the switchgear in the RR is from BMW. I don't want to buy an X5 cause I'm getting rid of mine for the new SUV, and I don't like the MB ML or G series. Any comments, guys?