I have a 1999 sebgring convertible. When the car is started when it is cold you can hear a tinny vibration sound for about 1 minute. When you put it in drive it stops. It does not do it when it is warmed up
This would be typical of a loose heat shield around the exhaust pipe or catalytic converter, particularly if you don't feel it inside the car. Very often when a weld breaks you can use a regular radiator hose clamp to hold it from rattling.