Originally Posted by Shawnkey
It is the rear differential teeth mateing, since it's not at a load, but not dec elerating, you do get some noise. If it is real loud, and gets louder with raises in speed, there might be a problem. If you buy make sure there is a transferable powertrain warranty, that will cover it for 7 years 70k miles.
Shawn
I agree, Mine does the same thing. The reason you can hear it is because the rear diff. is right behind the bulk head and there is no separation between the passenger compartment and the trunk area. I would suspect that almost all rear diffs. make this noise, you just don't hear it because in most vehicles the rear diff. is separated by the trunk .