Photo: Kia

Sunroofs on dozens of newer car models from around the world are shattering spontaneously, leaving owners perplexed and seeking answers. But while even experts don’t know entirely why this is happening, we do know which cars are yielding the most complaints to regulatory agencies.

Canadian news site Global News writes about a couple driving to a doctor’s appointment with their three-month old child, when the sunroof in their 2016 Volkswagen Jetta shattered, showering bits of glass onto their baby, and causing the driver to swerve the car.


This wasn’t the only complaint of a sunroof shattering seemingly instantaneously. The news site says that, according to data from Transport Canada, complaints about exploding sunroofs have gone from zero in 2007 to “over 110" in 2016, and those complaints already total 103 so far in 2017.

Global News writes that, since 2000, the regulatory agency has 351 recorded complaints about breaking sunroofs, with the list below detailing ten of the models that received the most:

  1. Hyundai Santa Fe, 37
  2. Nissan Murano, 19
  3. BMW 3 Series, 13
  4. Kia Sorento, 10
  5. Mazda3, 9
  6. Toyota RAV4, 9
  7. Nissan Rogue, 9
  8. Ford Focus, 8
  9. Ford Edge, 6
  10. Hyundai Elantra, 6

Earlier this month, Consumer Reports wrote a lengthy article describing this “exploding sunroof” issue in the United States, citing a mother named Heather Savage, whose 2016 Nissan Pathfinder had its sunroof explode with two of her children in the car. Luckily, her shade was rolled forward, and the glass didn’t enter the vehicle.

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The nonprofit group says in its story that of the 859 complaints filed by owners with the National Highway Traffic Safety Administration since 1995, 71 percent were logged in 2011 or later, and almost all were explosive:

...while some details vary, they’re identical to Heather Savage’s experience in this way: A sunroof suddenly shatters with no direct or known cause.

Consumer Reports, which writes that these sunroof explosions “have happened in every month of the year in every part of the country, in vehicles from all over the world” and on every type of road, found that the most common vehicles included in the 859 complaints to NHTSA were the Scion tC, Hyundai Veloster, Kia Sorento, Nissan Murano and Kia Optima.

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And those 859 complaints, Consumer Reports writes, aren’t truly representative of the total number of sunroof failures, with the site writing:

While owners of Kia Sorentos have filed at least 43 reports of shattered sunroofs with U.S. regulators, Kia has told NHTSA it has at least 156 Sorento sunroof cases in its own records. Kia Optima owners have filed at least 25 reports with regulators, but the company told NHTSA it is aware of 173 shattered Optima sunroofs.

Ford reported 88 sunroof explosions for its Edge crossover vehicle—11 times the number of complaints that have been reported to NHTSA.

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So clearly it’s a lot more prevalent of an issue than your average person might think, even if Consumer Reports admits that “the odds of this happening to you are low.”

Why Is It Happening? And Why Now?

One theory for why sunroofs are shattering has to do with manufacturing defects. Global News cites the head of research for a large glass repair company, saying contaminants in glass (which is often tempered for strength, but shatters instead of just cracking) can cause high internal stresses, especially in high temperature conditions, which can increase the chance of breakage.

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Consumer Reports spoke with someone who worked at major automotive glass company PPG, who said even a small chip on the “beveled edge” on the outside of the glass can make the sunroof prone to failure. That source also said thermal shock and loads associated with the twisting of the body as the car hits bumps could contribute to the sunroof “weakening over time.”

But the real issue, which Consumer Reports’ sources and Global News’ sources seem to agree on, is impact damage on sunroofs that have gotten much larger over time, with Consumer Reports reporting:

One problem is that modern designs are more three-dimensional and often involve bending glass to the curvature of the roof, notes Rob Vandal, senior director of research and development with Guardian Glass, a major American automotive glass supplier. That makes them more susceptible to impacts, even from very small objects, Vandal says, because they present a more vertical surface for an offending object to strike.

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Global News has something similar from its sources, writing:

What generally causes the glass to shatter is accidental damage, said Davies. A rock or even something as small as a pebble hitting the glass can cause it to shatter, especially if the glass has already been subjected to significant stress.

Indeed, “the majority of complaints received by Transport Canada involved breakage due to impact,” the agency told Global News via email.

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Sunroofs are getting big and geometrically complex, meaning accidental damage is more likely than ever.

What’s Next?

So basically, modern car sunroofs, which have become quite prevalent and also rather large and ornate, are prone to damage from a variety of sources, especially external impacts. This is not a particularly surprising revelation.

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Still, that doesn’t mean something shouldn’t be done about the failures. In March of 2016, the 2011 to 2013 Kia Sorento was recalled in Canada after it became clear that the sunroof was susceptible to shattering, especially on gravel roads.

Those same vehicles, says Consumer Reports, are under investigation in the U.S., with the nonprofit writing: “NHTSA has been investigating the Sorento for model years 2011 to 2013 since 2013, yet visible progress appears to have slowed since spring of 2016.”

There have been quite a few sunroof recalls in the U.S. over the years dealing with shattering sunroofs, with the consumer advocate noting:

Aside from its current investigation into the Sorento, the agency has conducted four previous sunroof-defect investigations since 2004. Two resulted in automaker recalls while the models were under NHTSA investigation—for the 2012 Hyundai Veloster and the 2004 Nissan Maxima. Two others closed with no defect identified—the 2004 - 2006 Cadillac SRX and the 2005 - 2006 Scion tC. Those two models are among the top 10 in consumer complaints.

Audi and Volkswagen have issued sunroof recalls without NHTSA first opening an investigation, Audi for its 2012 Q5 and the 2013 - 2014 A8 and S8, and Volkswagen for its 2013 - 2015 Beetle. A spokesman for both brands told CR, “We take the safety of our products seriously.”

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For its part, Consumer Reports suggested three next-steps on this issue. It wants all automakers with patterns of sunroof shattering to order recalls. It also wants regulators to “expand their investigation of the Sorento to include other automakers and models.”

And finally, Consumer Reports thinks “the auto industry as a whole needs to establish stronger safety standards for so-called panoramic sunroofs without waiting for regulators.”