I was driving down the highway at approximately 5 pm on a partly cloudy day that was not particularly hot (~94F) for this part of the country. I had been on the road for about 4 hours when I suddenly heard a loud "boom" similar to a shotgun blast come from the roof of my car. I made my way off the interstate onto the feeder road as quickly as I could. Upon getting out of the car I found that my sunroof had seemingly exploded. About 75% of the glass was gone. Some glass fragments were laying on the sun visor (as I had the sun visor closed at the time), but most of the glass was presumably along the interstate somewhere. The glass broke into thousands of tiny glass fragments. The glass that remained was completely cracked due to the nature of the tempered glass. The pieces of glass along fracture boundary were sticking up in such a way that the glass must have broken in an outward direction. There was no damage to the sun visor. Both of these pieces of evidence along with the fact that I did not see anything just prior to the incident show that the sunroof could not have been shattered by an impact from debris. The debris would have had to have been substantially massive to cause such damage to the glass. It would have certainly damaged the sun visor as well. In addition, the glass could not have flown outward after an inward impact from debris. This incident was caused by either faulty materials used for glass or improper design that did not account for all loads that could be applied to the glass. This incident could have easily caused an accident by startling me as the driver on the interstate. Also, the residual glass could have easily caused an injury to the driver or passengers in the car if the sun visor had not been closed. This is a very dangerous issue.

- Houston, TX, USA