I own a 2001 S60 T5. Every now and then there is a loud thunking noise from the right rear end after the car comes to a complete stop. The car isn't moving, so there is no way there is something loose in the trunk. Sometimes it seems to happen after rapid acceleration, then stopping. Usually it's after the car has been traveling over 50 MPH or so. My warranty is due to expire, and the dealer can't get the car to duplicate the thunk whenever I take it in. Anyone else have this problem? If I don't get an extended warranty, is this car going to suck me dry?

Can you get it to do it when ever you want?
If so take it back to the dealer and drive it with the shop foreman or service manager and have them hear it.
This way they will know how to make it happen.
Sounds like possibly a rear sway bar end link.