It applies to cars that start with the push of a button. The main problem is with 'proximity' remotes that open the car and arm the ignition when the remote is in the proximity of the car. These signals can be captured and boosted and the car opened and driven away as if the proximity key is present. There are all kinds of other ways a car's security can be breached, but the way to prevent a proximity key's signal being captured and boosted is to put the key inside a signal blocking Faraday bag. What I do is fit a Disklok to the steering wheel. That is too much hassle for a thief to try to remove.