We've been experiencing a whining noise as the vehicle starts and when accelerating from zero to road speeds. You can hear whining as the transmission shifts up through the gears. It's not too noticeable during downshift as is during acceleration. I took it to our Cadillac dealer for service, and they replaced the drive belt and tensioner, and the problem still persisted. I asked did they test drive the vehicle to listen to the whin and they did not, but we were out of $644.00 for the repair. Needless to say that I'm upset that you pay for a luxury vehicle and these things happen. I'm an engineer and I understand inherent failures, but if discovered, design a fix, fix the vehicle (s) and not charge the customer, especially since the customer has met all of the Preventative Maintenance Service checks that's recommended by the manufacturer. These vehicles aren't cheap, and the customer deserves excellent service because they've put their trust into the engineering expertise of the manufacturer.