Research from the provider also revealed that the items most commonly stolen from cars in the UK are CDs, GPS devices and mp3 players.
Sue Longthorn, managing director of Admiral, said: "Our data shows the items most commonly claimed for following a theft and therefore the things we commonly keep in our cars.
"It may be stating the obvious, but leave nothing on show in an unattended car. Our research shows car thieves will steal anything."
Recent research from Zurich found that many holiday home owners are not taking adequate steps to ensure their properties are secure.
It was revealed that one in ten people also do not have insurance for their second properties.
Click here to run an energy price comparison, and see if you could be paying less for your gas and electricity.