Are all cars vulnerable to 'relay' theft?

I've read more and more about the 'relay' method for car theft. Are all cars potentially a target, or only those which have keyless entry?

Asked on 6 January 2018 by Jon Jones

Answered by Honest John
Any key that transmits a signal when in the vicinity of the car (so the car opens without pressing any buttons) is vulnerable to the signal from the key being scanned and boosted so the car can be opened and driven away. To stop this, these keys need to be placed inside a signal blocking Faraday bag or placed at least 15 feet inside a building.
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