Drivers are inviting smash-and-grab thieves to break in to their cars by leaving valuables on display.
Around half of all drivers treat their cars as a shop window for thieves, according to insurance company Zurich.
Sunglasses (77%), clothes (28%) and sat-navs (20%) are the most common belongings left on show by drivers in parked and unattended vehicles, according to research by the firm.
Other easy pickings for thieves include with mobile phones, left by 6% of motorists, music players (5%) and cash (5%).
The insurer claims motorists underestimate the value of belongings they leave in their cars and are often not covered for the full value if a thief strikes.
The research findings showed drivers reckoned they left just £85 of belongings in their cars, while data from the British Crime Survey puts the average haul stolen from a car break-in nearer to £200.
Zurich’s Steve Gilbert said: “It can be a pretty distressing experience finding your car has been broken into. There’s the financial loss, as well as the added misery of when something irreplaceable or sentimental is stolen. It is vital that car owners don’t leave their possessions on show. Thieves don’t need an added invitation to break into your car so don’t give them one.
“It’s encouraging that fewer motorists are leaving possessions in their car – with the proportion falling from 85% in 2007 to 51% today – but it’s still important to remember that anything which has to be stored in the vehicle should also be locked-up.”
Gilbert also warns that insurers may reject claims for belongings that were left in plain sight and most car insurance policies do not cover stolen cash or credit cards.
Drivers should check their car insurance policies to see what is covered in a break-in – many insurers may have a low limit on cover or charge an excess for dealing with the claim.