probably something loose inside the dash rattling around. Since everything has a "frequency" certain speeds make certain things rattle (learned that in HS Physics). Maybe pick up a $5 set of radio pullers from Pep Boys and see if you can find anything in there rattling around.

-Tim

2006 Mercury Mariner Hybrid AWD
Black with Pebble interior
Premium Package with Nav & Moonroof



Current ODO: 26,152
Typical Drive: 20 min crosstown in heavy traffic (3.5mi there and back twice a day)


532 Gallons of gas saved
That's 10,642 lbs less CO2 emitted