Mine is a 95 model and I notice a slight vibration, a dull roar, when reaching a speed of 55 or 60. That is where it begins. It almost sounds as if it is below the shifter or console in between the seats. If not for this noise, the car would be very quiet. I plan on taking mine in for inspection and will let you know what it turns out to be. Thanks to all before me, that posted possible causes, so us new members have somewhere to start.