Ever since I've bought my XF, there has been an "air" sound coming from the back of the vehicle when the doors lock or unlock. I disregarded it because its an air pump. It will make noise. It has gotten progressively worse, and I have discovered that I have an air leak in the tube that goes into the hatch. Now the hatch doesn't unlock everytime, and the pump runs for about 15 seconds, and you can her the leak from outside the car. So, the car will be going back to the dealer, again, to fix that, the wind noise problem, and my diff (80 mph whining). I'll let you know how it turns out.