There was an article recently about the increase in theft of vehicles fitted with keyless entry, Apparently for very little money it's possible to buy a signal relay box that boosts and bounces the signal from the key to the car - allowing thieves to unlock, start and drive away the car, just by standing in range of the key - which with newish batteries is certain to be outside the house. As long as they don't turn it off before getting to the chop shop, it's plain sailing. The recommendation was to always keep the keys overnight in an RFID container which blocks the signal from the key until YOU want to unlock and start the car.
On a side note, this reminds me of a cautionary tale I heard when keyless entry was just being introduced. A man got into his car for a meeeting in London. He set off and parked up in a carpark having reached his destination. When he came back to his car, although he could get into it, it wouldn't start. Turns out he'd left the key in a jacket hanging up in the hall at home. The key had the range to reach the car on his drive, enabling him to set off, but of course wasn't able to reach the 200 miles to London where he was parked. He had to have the car recovered back to his house.
