Police are urging owners of keyless entry cars to take additional steps to protect themselves from theft.
The warning comes as criminals are exploiting technology to steal high-value vehicles.
Durham Constabulary said that keyless entry car theft is gaining proliferation nationally. Criminals manipulate the vulnerabilities of the keyless system by using a 'relay' device to capture the signal from the car's fob and trick the system into believing the keys are with the vehicle so that it can be unlocked, started and driven away within minutes.
Officers recommend that drivers store their keys in a 'Faraday bag' to avoid being a victim of this crime. These are made of flexible metallic fabric and are used to block out electromagnetic fields, preventing any unwanted communication between the key and the vehicle.
"Vehicle security technology is constantly being advanced by vehicle manufacturers but unfortunately technology is also being developed and used by criminals to combat these new measures," said Superintendent Kerrin Wilson from the Cleveland and Durham Specialist Operations Unit (CDSOU).
"The use of Faraday bags is a low-cost, effective solution and by popping your keys into the bag, the signal will be blocked and your car will be safe.
"The other added benefit is to put your mobile phone in the bag when driving thus blocking the signal, stopping your phone from distracting you and reducing the temptation to check your messages."
According to Durham Constabulary, surveys have shown that 13% of drivers leave their car keys on their hallway table, while 25% leave their keys in a key pot or on a key hook and 15% put them in a drawer downstairs.
Supt Wilson added: "Putting your keys in a drawer may make you feel safe as they are out of sight, however this does not deter or protect you from being a victim of this kind of theft. A Faraday bag will."
West Midlands Police recently seized what are believed to be the first relay devices in the country to be recovered from criminals.
Mark Silvester from the West Midlands Police crime reduction team said that owners should consider getting a Thatcham-approved steering lock which covers the entire steering wheel to protect against this type of theft.
"We also recommend Thatcham-approved tracking solutions fitted to the vehicle," he added.
Does your car have keyless entry? Do you take any additional measures to prevent theft?