I've been in an iffy situation like this, alone with a stranger behind the wheel. All of my instincts had me playing it cool, I even took his number and said I would call. I felt like reacting with alarm would alarm him (an unpredictable variable), also, he was driving. It's humiliating not to be able to fight back, but survival instincts are there for a reason. I probably would have spit in his face when I got out though...