Auckland police are trying to turn the city's parking buildings into crime-free zones by cheating thieves of any chance of grabbing valuables from cars.
They are asking drivers to remove or hide treasures from sight, and to display bright yellow cards in car windows declaring there is nothing left to take.
Drivers entering Wilson Parking's multi-storey building on the corner of Hobson and Wyndham Streets - formerly the Farmers' car park - were stopped by police yesterday morning and offered yellow cards.
"No one got away without one," said one commuter, who was warned of an "epidemic" of smash and grab break-ins of cars in parking buildings around the city.
Sergeant Roy Simpson, an Auckland Central police crime prevention leader, denied his staff were dealing with a major outbreak but acknowledged an increase in thefts with the approach of summer and Christmas shopping.
"There has been a slight increase - not a major crime wave - so what we do with anything like this is we try to stamp on it straight away," he said.
"Unfortunately, in the summer months with the sun shining, some less desirable people are coming to the city to prey on people doing their shopping."
Police will visit other parking buildings, including Auckland Transport's, this morning and in coming days as well as car rental companies, to pass the yellow cards on to tourists.
Companies leasing staff parking spaces would also be approached.
"We are trying to get the message to all car-park companies, and vehicle owners to just think a bit before you jump out, slam the door and lock your car," Mr Simpson said.
"If you put everything away and thieves look in your car and see nothing, it's quite simple, they move to the next one."
He had seen all manner of valuables left on display in parked cars - "you name it, iPads on charge, iPhones, sports bags, cameras".
Mr Simpson said police were pleased with an increase in CCTV cameras in several Auckland car parks, including another Wilson building being upgraded further up Hobson St.
"I think they had minimal CCTV but now they are going to have it on the [multi-level] floors, which is good news."
Although CCTV footage had led to "numerous arrests" after thefts in city parking buildings, the education campaign was aimed at pre-empting pointless damage to vehicles where there was nothing to be found.
A Wilson Parking spokeswoman said vehicle crime was a problem for both on and off-street parking, and the company was happy to co-operate with the campaign.
She said it had a network of CCTV cameras throughout its parking buildings nationally, monitoring them around the clock from a control centre in Queen St.
An Auckland Transport spokesman said high levels of security were maintained in its council-owned car parks, supported by CCTV cameras.