Re: "...can pick up the signal from keys..."
Can't speak for other makes (although have seen the Facebook CCTV video of repeater theft on a Mercedes) but on my Renault the keyless entry only works if you don't use the remote to lock the car after you turn the engine off, ie you just shut the door and walk off, it then locks as you walk away (it beeps). Then on your return if you stand within a metre and someone puts their hand in the door handle it unlocks. If you lock the car with the button on the remote key card, it won't unlock unless you unlock it again with the (different) button on the keycard. So would guess it's safe from repeater attack as long as you lock it with the remote.....