Ever since we first drove off the dealer lot have had this problem. Have taken it back to the dealer but they either don't hear the shrill noise or they just shrug off casually saying it is normal. This shrill vibration or resonant frequency start at around 55 MPH and when the engine speed is around 1400 to 1500 rpm. Is there anyone out there that is or has experienced this problem? What did you do to fix this? Thanks.