Two Calgary drivers want an explanation for why the sunroofs in their vehicles exploded as they were driving.

Kerri Mullen's fiancé was driving her Audi Q-7 SUV on Deerfoot Trail in Calgary, with her in the front passenger seat and a friend in the back seat, when they heard a loud bang.

"Out of nowhere we heard a pop, a loud explosion sound and then it started raining glass," said Mullen.

No one was seriously injured but they did receive some cuts.

Transport Canada has recalled 1,800 2012 Audi Q-5 vehicles because of a flaw in the front sunroof, but Mullen said the dealership is still trying to find the source of the explosion in her SUV.

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The sunroof on this Audi Q-7 exploded as the vehicle was travelling on Deerfoot Trail. (Courtesy of Kerri Mullen)

"They said they will speak with their head office to see if they can diagnose it. They couldn't figure out what the problem was so they’re covering it under our warranty."

'It just blew up'

Calgary driver Jason Baker is not getting the same help from Nissan Canada.

He was leaving a parking lot at work when his sunroof exploded.

"It combusted. It just blew up and shattered glass all over me basically. I got a few cuts on my hands. It ripped my dress shirt. My leather seats are cut," said Baker.

Nissan Canada, in a written statement, said Baker’s sunroof had been damaged by a rock and the explosion had nothing to do with the sunroof or the workmanship.

"I absolutely think it should be covered under warranty. It’s a $1,500 out-of-pocket expense for me that could have been much worse, not just the money. Had I had my twins in the car or my three-year-old … it has to be a safety issue," said Baker.

A regular occurrence, say consumer blogs

Some consumer blogs suggest exploding sunroofs are a regular occurrence. Baker said he was told the same thing at his dealership.

But the Alberta Motor Association said it is a rare occurrence.

Randy Loyk, AMA manager of technical services, said a sunroof can be weakened by a rock chip.

"Once a piece of safety glass has a small mark on it, it is compromised and any temperature change, pressure, just even pulling out on a roadway or hitting a pothole, can cause these pieces to flex and that will cause the glass to shatter."

Loyk said drivers can buy a transparent film that can be applied directly onto the glass to protect the roof from chips and scratches.