"While we have seen extreme cases where windscreen repair claims can reach this level, it is rare as they are typically in the very latest models and vehicles retailing at more than $100,000.
Mason says this is unfair, and leaves owners of older cars essentially having to shell out because others' cars cost more to fix.
"Putting this in perspective, the average age of the four million vehicles in New Zealand's fleet is more than 14 years - and you can pick up a standard windscreen for an older model for less than $200," she said.
She said there is concern that the policy could be taken up by other insurers in the near future.
"Consumers need to make sure they speak to their broker and read the policy fine print when they next renew their insurance, and should consider shopping around for the best coverage package that suits them," she said.
Craig Pomare, chief executive of the Motor Trade Association (MTA), said he was concerned that if all companies start charging the policy excess for windscreen replacements, it could result in more people driving around with seriously damaged windscreens.
"This poses some real safety risks in an accident as the windscreen is part of a vehicle's structural integrity," he said.
"Any car with damage to the windscreen will fail a warrant so it is safer to replace it immediately rather than wait until the warrant is due."
The MTA is urging people whose insurance companies stop offering 'free' cover for glass to shop around.
"This isn't likely to happen quickly, so people should shop around when renewing their insurance," Pomare said.
A spokesperson for AA Insurance told the Herald that they currently have no plans to change their excess-free glass cover.
"At AA Insurance, we provide our customers with excess-free glass cover as an optional benefit on our comprehensive and third party, fire and theft car insurance policies. Some customers choose not to take this option to help them save on their premium. Customers who do choose this option however, won't need to pay an excess on claims that only relate to the accidental damage of their windscreen or windows.
"We are here to look after our customers' cars, no matter what the age, so currently have no plans to change our excess-free glass cover, or reduce cover as a response to changing technology in cars."