Without warning, sunroofs shatter into 'a million pieces'

The fresh air, light and open feel – for many car buyers, sunroofs are a must have.

But plenty of owners are finding the must-haves might bust – big time.

Niki Wheeler said she was in her car when “all of a sudden, it was like I heard a gunshot. And it was so loud.”

The bang was the sunroof on her brand new Kia Optima. It exploded as she drove down busy U.S. Highway 1.

“It had literally shattered into a million pieces,” she said.

The saving grace was that the sun roof visor was closed.

“If the canvas hadn't been pulled, not only would I have gotten hurt, seriously, but I would have got in a wreck,” Wheeler said.

She called her husband, and he – like the dealership – said something must have hit the roof.

“I would have seen something or heard it,” Wheeler said. “But it wasn't like that."

And it wasn't like that for dozens of others.

Our 5 On Your Side investigation found complaint after complaint about exploding sunroofs. Drivers describe that loud gunshot noise, then shattering glass, with no signs of any bullet, rock or road debris having hit.

"From BMWs to Kias, to Fords,” said Neill Wheeler, Niki’s husband. “From Denver to California to North Carolina, there's no rhyme or reason for the who, what, when or where. Just sunroofs exploding while people are riding down the road."

“I've had five cars that we've replaced the sunroofs,” said Chris Latham, owner of Glass Solutions.

Latham, who’s been in the glass replacement business for 34 years, said the common denominator is tempered glass. It's designed to break into tiny pieces, instead of large shards, for safety. But it breaks easily.

“And that's what falling on their heads if they don't have the sunscreen,” Latham said, breaking a piece of tempered glass to demonstrate the shower of pieces.

Laminated glass, used primarily in windshields, doesn't break like that. It cracks and spider-webs because a thin layer of plastic in the middle holds it together.

Latham demonstrated by striking a piece of laminated glass, which doesn’t shatter.

“And I'm hitting that a lot harder, but you don't see it disintegrate," he said.

As for what's causing sunroofs to explode, there isn't a clear answer yet. But Latham shares the thoughts of other experts we talked with and tracked online.

First, cars are built more air tight than ever before. That could contribute to some of the failures. Also, more and more glass is being manufactured in places such as China and Mexico. While it meets standards, it's thinner and lighter.

But the biggest and perhaps most important factor is temperature change. Many of the reported sunroof explosions happened on hot days, especially after heat was trapped between the sunroof and a closed visor. Some sunroofs shattered on extremely cold days, just not as many.

One possible solution: On hot days, keep the visor open a little so heat doesn't build up.

"You know the heat is coming in, but with that being said, it's distributing the heat throughout the car instead of being trapped in an inch space," Latham said.

Then before you drive, vent the sunroof or other windows.

As for the Wheelers and the shattered sunroof on their Optima, Kia sent a statement saying the company "has not opened an investigation regarding sunroof glass failure" and that damage claims are "handled on a case-by-case basis."

The couple believes it’s time for the federal government to get involved.

“Oh, I think it's absolutely a defect,” Neill Wheeler said. “I can't tell you exactly what the defect is, but again researching online I’ve seen where the same vehicles have exploded more than once."

"I just really hope that someone looks into it,” Niki Wheeler said. “So that nobody gets hurt."

5 On Your Side also contacted the National Highway Traffic Safety Administration about the concerns. They gave us a one-line statement, saying they “don’t comment on open investigations.”