I recently purchased a 2005 XC70 and love the wagon, but at idle it is loud. I would think that this car should be very quiet at idle, but instead there is an annoying low pitch reverberation type noise that is loudest at around 900 rpms. Has anyone else experienced this?

Check with the dealer and make sure there isn't any tech notes for a repair for that.

Get it to the dealer and have them look at it.