I have the 19 Classics and have the same noise. Only happens under sharp left/U-Turns.

I took it to the dealer & drove the car for the tech. He heard the sound and then put it on a lift and found nothing wrong. He then took another CS out and it made the same sound, so they said it was normal.

It is a rattle or wheel rubbing on suspension/wheel well sound.

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2006 CS Cobalt Blue
2008 xB
2005 Tacoma