On my C6 I had a vibration at 1200RPM, took to dealer, they found a loose screw in the engine compartment that was holding down a cover. I have also notice a rattle in the rear when I hit uneven pavement. Next time I have it in I will get the dealer to look into that as well. Other then that, Fine ride.

One problem that I have notices is that sometimes the HUD will not display on the window. I have to turn of the car and start it again to resolve. It's happen a dozen time since I took delivery in September 2004. Need to ge the dealer to look into it the next time I have it sericed.