There are an infinite number of ways that "terrorists can kill people". Remote control cars is only one of them and probably nowhere near the top of the list.

There are an infinite number of ways that "terrorists can kill people". Remote control cars is only one of them and probably nowhere near the top of the list. We defend against killer-remote-control-cars like we defend against all forms of terrorism: plain old police and intelligence work to snatch the perps before they have a chance to strike.