I have owned two SC430s and one GS350 - all wonderful cars and very quiet. In addition, we have an old, very reliable RX330, also wonderful. That said, my ISC 250 has under 10,000 miles and produces an incessant squeak from the rear of the car that sounds like leather rubbing together. As time has gone along, the sound worsens. It is extremely distracting and is unacceptable in a vehicle of this alleged quality. Had this been my first Lexus, I am sure it would be my last.