Police in Lincoln have spotted valuables on show inside over 400 cars parked in the city.
Officers on Operation Handbrake patrols to tackle vehicle theft discovered the items left on display in vehicles found in the north of Lincoln during a two-week period.
The owner of a car containing visible possessions of interest to thieves will receive a letter from police warning them of the dangers of not leaving their valuables out of sight.
Items targeted by criminals include sat-navs, cash, CDs, phones and laptops - all of which were spotted in cars during the operation.
Inspector Ian Richardson said:
“We know people still do this, but we were surprised by the sheer volume of it. We constantly pump out crime prevention messages on vehicle crime, but people are still doing it. It takes seconds to smash a car window and grab something like a sat nav and then you have the cost and inconvenience of replacing it and getting your car mended.
“We have made several vehicle crime arrests over the past few months and our officers are very much focused on reducing this type of crime, but we need the public to work with us. Please remove all property from you car when you leave it unattended – it will dramatically decrease your chances of becoming a victim of crime.”