An acquaintance of mine who purchased a new '08 CTS about 6 months ago stated to me that she's noticing a "vibration" and a "whining" noise at about 45 MPH. Dealer is going to be checking it out. I thought the '08's eliminated this dreaded rear differential problem. Hopefully, it's something else. Anybody else experiencing this yet? (This is the same girl who's locks wouldn't open with fob or manually with the key - she had to call On-Star.)

thud

If it makes you feel better, I had the differential on my 04 replaced at 11,000 miles. The car had 82,000 miles on it with no further problems when I traded it for my 08.

Rear differentials often make a slight amount of noise- I wouldn't be getting ready to avoid chunks of falling sky just yet.