Drivers are being urged to remove their satellite navigation devices from their parked cars after scores of thefts. Hampshire Police say thieves are particularly targeting the Test Valley, New Forest and Eastleigh areas.
Since January, there have been 123 thefts or attempted thefts of the devices across the three areas, with 38 during last month alone.
Police are also urging to drivers clear away anything that might suggest there is a device hidden in the car.
These include suction pad marks on the windscreen and the holding cradle for the sat-navs themselves.
A police spokesman said: "Just because you take your sat-nav out and leave behind everything else, doesn't mean you're safe.
"Thieves may still break into your vehicle hoping to find a device left in the glove compartment if they can see evidence of one."