My 2005 Cadillac STS V8 (7,000 miles) rear window shattered (inward) this week. It was early in the morning after the car had been sitting outside (Chicago) in 20 degree temperature. I got in, started the car and turned the rear defroster on to melt the ice that blanketed my rear window. My wife got in the front passenger side and shut the car door hard. At that very moment, I heard what I thought was ice sliding off of my rear window. Unfortunately, what I thought was ice was actually glass.
The shattering left a large open circular pattern in the rear window and the remaining glass was completely spidered.
There was no impact on the window, the rear window defrost was not left on overnight (which is not possible anyways) and there are no other apparent causual factors.
The dealer is replacing - no questions asked - although they did point out several small dents in the trunk (from luggage being dropped onto the trunk) implying something else may have caused the shattering. The dealer also wouldn't acknowledge knowing of other customers with similar shattering issues or any known defect with the window (manufacturing or installation).
I suspect this is some kind of defect. Overall, I have found the 2005 STS to have more issues that my previous 3 Cadillacs - probably related to the increase in high technology and overall system integration., my XM stopped working 2 months ago and will finally be fixed along with the window. The first time that I brought the car to repair the XM, it took 30 minutes for them to determine that they needed several days to just diagnose the problem.