I have not seen this done with Anim8or but it is certainly an intriguing project. I would suggest using morph targets to actually deform the cars at the collision point, and you would want to have a pretty good idea of how the car is to crumple when you actually build the cars themselves, so you have wireframe edges along crease lines. I would recommend Googling a few car crash videos or stills, from crash test collisions, to get an idea of how car bodies react when slammed together (modern cars have built-in crumple zones, or weak spots in the subframe, to ensure the car body folds up in a predictable way, away from the occupants).
If you haven't already done so I would also recommend a thorough read of the manual, and maybe check out a couple of tutorials on edgelooping (to build the car bodies) and morphing (to animate the bodies crushing). A good sense of physics would also be an advantage, to define the motion of particulate matter like glass and metal fragments broken off in the collision.
I really look forward to seeing how you go with this. Please post a WIP when you get this under way, and don't be afraid to ask for help from the Anim8or community. Good to have you aboard and good luck!
