I did this once, it was pretty easy to set up a large sheet of plastic
(I am talking 20'x20') up the side of the garage wall and the ground and
shoot the car, I was able to recycle most of the media and re-use it by
doing this. And as someone already suggested it was not worth it. My
media costs were nearly the same as having a professional do it and it took
me a week to do, an hour here, an hour there.
Set up a backboard of some kind, I used the garage wall and shoot in
that direction (don't hit it) and you will be able to recover most of the
media and scoop it back into the blaster.