The insurance company paid out more than $810,000 for thefts from car claims, with an average of $1700 per claim, according to data for the 12 months until October 31. This was comparable to last year's figure, Ms Macandrew said.
"Our most common claims are personal items such as clothing, makeup and handbags, followed by mobile phones, then laptops and iPads," she said.
"Although at this time of year it's not unusual for Christmas shopping, travel items, and even groceries to be stolen."
Most thefts were opportunistic and were often committed while drivers had left their cars for a short time, she said, describing one customer who took her dog for a walk along the beach and when she returned an hour later $5000 worth of contents had been stolen from her car, including her mobile, camera, laptop and hair straighteners.
"We often forget that the items we regularly carry with us can add up to hundreds, if not thousands, of dollars," Ms Macandrew said.
"If you were carrying the equivalent amount in cash, you'd likely do your best to protect it from being stolen. Yet we're not as vigilant when it comes to looking after our everyday items that are often valuable and sentimental, like irreplaceable images on our phone.
"Our key message to Kiwis this holiday season is to keep these important possessions out of sight or, better yet, take them with you. If you put your possessions at significant risk, you could jeopardise your claim from being accepted."
Tips for preventing car break-ins:
* Lock your car, no matter where it's parked and keep your keys with you - 15 per cent of survey respondents admitted they don't always lock their car, such as when they're at home or at the service station.
* Don't display your belongings. If you need to leave items in the car then keep them in the boot.
* Take valuables (eg wallet, mobile, iPods) with you - don't leave in the glove box or under a seat.
* Park in busy, open, well-lit areas. Use an attended, secure parking building if you can.
* Remove the detachable faceplate of your stereo, GPS cradle and mobile charger.
* Tell your neighbours if your car has been broken into - thieves often target cars in the same street.
* Install additional security to your car such as an alarm, or immobiliser.