ActionScript 2.0 :: HitTest Of Actual Picture Rather Than The _x/_y Portions?

I am quite a way through creating my own game from scratch and i have smacked straight-on, head first into a triple layer brick wall.As it is I have my hitTest code(Below.) which detects a hitTest on the _x and _y positon of my car MC. The code is placed on the background, however, as the car mc is large it overlaps the wall when they are driving, until the _x and/or _y position are colliding.So, basically, I need it so it goes off the hitTest of my actual picture rather than the _x/_y postions,My code(partial) at the moment;

Code:
.....
x = Math.sin(_root.car.dude._rotation*(Math.PI/180))*_root.speed;
y = Math.cos(_root.car.dude._rotation*(Math.PI/180))*_root.speed*-1;[code]....