In the 12 months from November 2014 to October 2015, 6700 cars were broken into, with items ranging from money to high-end electronic devices stolen.
Inspector Rod Petterson, from the South East Metropolitan district office, said officers-in-charge from across the region were keen to encourage people to lock their cars at all times and take all their valuables with them.
�When people leave items in their cars, it is like a magnet to (thieves),� he said.
Insp Petterson said traditional hiding spots in cars, like under seats or in glove boxes were no deterrent for opportunistic thieves who targeted shopping centre carparks, driveways and foreshores.
�Until (thieves) realise people aren�t putting things under their seats, this will keep happening,� he said.
�We know from reports that things hidden under seats are going missing.�
Insp Petterson said the thefts were occurring at all times of the day, particularly in the evenings and early mornings.
�Sometimes people park their cars to do exercise and leave their belongings in their cars, and return to a car (that has been broken into,� he said.
Insp Petterson said the inconvenience of repairing smashed windows, cancelling credit cards and cleaning broken glass should motivate people to be more careful.
�A car theft is an inconvenience to people,� he said.
�There are (tablets) being taken filled with treasured photos lost forever.
�We will continue to repeat the message.
�Our proactive patrols have had an impact but people making themselves less vulnerable will have more of an impact.�