i had done what sam suggests and it works very well, using mags to crush parts of the car, and flatten the tyres, i managed to make a bit of a junkyard (got a bit carried away there!!LOL) and i also made some rusty mats for 'em in vue, 

the benefit of vue mats is that you can just keep mixing stuff together, so you can easily get burnt and paint and rust and raw steel all together.