I've given that some thought, myself, Aaron. I haven't tried it yet, but an old body might be a great practice canvas. Here's what occurred to me: After finishing the body (including BMF and decals ~~~ I hadn't considered decals, but it might work), dust a light coat of clear over all. After the light clear coat has dried, lay a heavier clear coat on and before it can dry, run a stiff bristled plastic brush along the side of the car from front to rear. I'm thinking a plucked brush, with only a few random bristles left intact. Repeat for the other side.
The brush I envision is one of those cheapies with coarse, stiff plastic bristles like a cheap hand broom, etc. By pulling some of the bristles, you could make the scrapes randomly spaced and irregular so it doesn't look like you just ran a saw down the side of the model.
As I said, I don't know how well it would work as I haven't tried it yet, but I've been trying to conjure up a process for some time and this seemed the most likely to produce the desired effect without cutting all the way through the finish to bare plastic.
IF you try it, let us know how well it works ... or doesn't.
Good luck!