The type of glass used in sunroof windows can shatter without warning into thousands of tiny shards, and the I-Team found hundreds of complaints within the National Highway Traffic Safety Administration's database from drivers who had it happen in their cars.
Rebecca and Phillip Causey were driving on the highway in December when they heard a loud pop above them. They rolled back the sunroof shade and glass shards rained down on their heads.
"The glass had bowed upward," Rebecca Causey said. "That’s not something I had ever noticed about the car."
But what the Causeys experienced is not so uncommon. Both Audi and Hyundai have issued voluntary recalls of some models because of similar sunroof issues.
Experts say that while laminated glass, which cracks when it is hit but rarely shatters, is required in car windshields but is not often used in side and back windows or sunroofs. The kind of glass that is used more often for those windows -- tempered glass -- can shatter suddendly and break into tiny shards. And some say it's far less safe.
"It's just a matter of design," said Donald Phillips, an engineer who consults in accident investigations and specializes in automobile glass. "Anything goes out of adjustment it's going to blow the roof."
Phillips says many car companies design the seal around sunroofs tightly so the car is quiet. But that same feature means the glass is under pressure, and something as minor as a sharp turn can cause them to shatter.
Phillips says it would cost only slightly more to use laminated glass for sunroofs and side windows. It would help protect drivers from being ejected from their vehicles in serious car crashes, he said. Phillips also said he has seen cases where tempered glass has caused serious lacerations in crashes, though many car companies say it can't cut you.
Acura told the I-Team there's no defect or design flaw that caused sunroof in the Causey's car, a 2012 Acura RDX, to shatter.
"Unfortunately, glass is susceptible to environmental impact," the company said.
The dealership is paying for the Causey's new sunroof, which costs $900. Meanwhile, the Causeys want to warn other drivers.
"It seems like this could be really serious," Phillip Causey said. If the shade had not been covered and it had popped and there was a lot of glass, we might not be sitting here talking."
Phillips keeps a comprehensive database of which cars use the most laminated glass in their windows. He says Audi uses more laminated glass than most. Mercedes, BMW, Chrysler, Chevrolet and Buick also use a lot, though it varies depending on the year and model of the car.
To find out what kind of glass your car windows are made of, check with your local dealership. To see whether there have been complaints or recalls on your make and model, go to safercar.gov/ and look up your year, make and model.