Wired just ran a good article on RFID keys for cars. While RFID-keyed cars were initially touted as "unstealable", it turns out there are plenty of ways for thieves to steal them, including, in some cases, a secret series of pushes and pulls on the emergency brake that reset the RFID authentication system. Regardless, insurance companies are frequently denying claims.
Full text: http://www.wired.com/wired/archive/14.08/carkey_pr.html
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