Transcript for Spontaneously Shattering Sunroofs Prompt Federal Investigation
while waiting at a stop sign. All of a sudden we hear what sounded like a gunshot. Reporter: Wade Owens says his shattered while driving on the highway. The glass caves in, boom. Reporter: Plus, more stories online about drivers in shock. My sunroof exploded in front of my eyes. Glass expert mash meshalum demonstrate what is it looks like when a sunroof shatters. Even pushing it down to simulate it falling on the driver. The cracks go at over 3,000 miles an hour so in an absolute instant this glass is completely broken. What's going on? Reporter: Most are made of tempered glass for your safety breaking into smaller more rounded pieces instead of sharp dangerous shards but experts say that can lead to spontaneous shattering if there's a manufacturing defect. The glass is constantly in tension and just like when you put a pin in a balloon it catastrophically breaks, the same thing happens with tempered glass. Reporter: "Gma investigates" finding nearly 400 complaints in the national highway traffic safety administration's database across all makes and models. Nhtsa telling us it's reviewing the complaints and investigating certain Kia sorentos. Kia is telling us it's evaluating the performance of the panoramic sunroofs in the 2011 to 2013 vehicles but in their investigation have found only foreign objects such as rocks and gravel have been identified as the cause of sunroof breakage. Now, some auto safety experts are calling on nhtsa to create new safety standards for sunroofs. Like requiring them to be made of laminated glass like that used in windshields. Which when hit remain in place to protect the driver. You should not have to ride at risk worrying about whether your sunroof is going to explode over you. Reporter: For "Good morning America," Mara schiavocampo, ABC news, New York.
This transcript has been automatically generated and may not be 100% accurate.