Police are urging drivers not to leave valuables on display in cars after officers spotted property in more than 400 vehicles in the north of Lincoln in two weeks.
Officers regularly carry out Operation Handbrake checks in the city in a bid to drive down vehicle crime.
PCs and PCSOs patrol the streets and identify vehicles with property on display. They then write to the owners and let them know, urging them not to do it again and offering some general crime prevention advice.
In the last two weeks officers in the north of the city, where higher levels of vehicle crime are recorded, identified 406 cars with property in clear view.
The property ranged from cash and CDs to smartphones, laptops and sat navs.
Lincolnshire Police 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 focussed 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.”