hitTest Problem

I dont think my code works;
if (this.hitTest(undriv)){
speed = 0;
}
Im new at hitTest and need some help.
I have created a fla with a car, which u will be able to drive only on the road, not outside of it. I have created 1 MC and erased in it (the roads is the erased) and when the car hits the outside of the road, it will stop.
My AS dont seem to work, i dont really know if i can do it like this.

EDIT: I got it working
Still, is hitTest good? isnt there other things that will detect if they collect with another mcs?