40,000-45,000 miles: Window regulators, both rears went out in the last 4 - months. You got it $800.00 wanted to repair them. ($250.00 each regulator plus labor on each door) GM BUICK HAS TO KNOW! It doesn't take a rocket scientist to see the problem when looking at the light plastic used that cracks, breaks down and allows the window cable that is under tension to pull out. My wife drives this car back and forth to work, that about it, the rear windows on this vehicle have only been down a few times we open the sun/moon roof for air. I was able to repair them myself for no cost just my time. (I had to buy a panel removal tool for the door covers, $5.00) I fabricated a small metal cover to fit over the plastic and re-tensioned the cable, better than original.
Spark plug wires on the back side if the engine broke down at about 35,00 miles. The tech said it was due to the heat from the exhaust. Maybe shielding or re-routing may eliminate this problem.
Brake rotors all (4) had to be replaced at 45,000 miles. Tech said the original GM ceramic pads ware the rotors down to below specs just about the time that they (The Pads) need to be replaced. So it sounds like GM needs to beef up the rotor material. Anyone replacing brake Pads/Lining trying to eliminate rotor damage is going to run into rotor trouble anyway!
Both front turn signal light sockets had to be replaced in this vehicle due to water getting into the sockets and rusting out the contacts. So when your turn signal quit working you might be in for a surprise cost to replace the bulb sockets. They are not easy to get to, the large plastic splash cover underneath has to be removed. This requires a special tool to pull the plastic retaining pins. When replacing the socket and bulb I coated the bulb terminals and socket interior with grease to prevent water from getting inside again. (A silicon would probably do the trick too) GM could have done this prevention...