heres an interesting article from C&D about stealing keyless entry frequencies. some of you may have read it before.
according to the article, its virutally impossible to steal someones car this way:
Here’s how it works: To issue an unlocking/locking action, the transmitter sends a request to the receiver/control module in the car. With the request, the transmitter also sends a new code sequence and TIC to the receiver. To issue an unlock/lock command, the code sequence and TIC sent by the transmitter must be one that hasn’t been used before and the next—or one of the next few—in a planned sequence. This is what is known as a rolling code. And there aren’t just a lot of possible codes; there are a whole buttload of them—4.8 million billion combinations. So even if thieves did manage to steal the TIC and the code sequence from the transmitter, the chance of stumbling upon that crucial next code is one in 4.8 million billion. Good luck with that.