We purchased a used 2009 Chevy Cobalt. When we get the car up to about 65 mph we hear a fairly loud vibration/rumble strip noise. The car is under warranty. The dealer has replaced both front hub bearings, front brake rotors, and brake pads. This has not solved the noise. We need to get this fixed. Has anyone had this problem, and what did the dealer do to fix the problem. Thanks.