In December I took delivery of a 2008 BMW X5 3.0si. This is my third X5 -- my previous 2005 and 2002 X'5's were superb and I never had any complaints with either of them.
The 2008 suffers from the same problem identified above, acceleration hesitation with an approximate 3 second delay and distressing lackluster performance. I have taken the car to service only to be told that it is simply the model, and also drove yet another new X5 3.0si with the same issue. After owning two other X5's I am very familiar with how they should perform. This is enormously frustrating with a car that is a little over a month old. I am hoping that the relay problem identified in an earler post may be the problem. The car will go back to service next week. I have been dealing with BMW directly which has not been helpful. It has taken much research to find myself here with a possible solution. I will followup with how this shakes out.