i like Zach's response, if there is any hope at all for the car, leave it be.
but where i grew up in LI there were all these fireroads in the woods- we didnt think of it then, but most of the cars were propabably ditched stolen. some were just plain abandoned.
many people shot them up, they were pretty destroyed by the time we got to them.
we were very young, we used hammers , rocks, whatever.
the big problem is these days the vehicle is most likely stolen or crime related, so i would have to think i would not start shtooing at it, plus here in the forest where you can shoot, there are rules, i wouldnt take the chance of a ranger rolling up on me.
besides a car is so big, too easy. i get my "destruction" fun at work hauling junk.