https://sourceforge.net/blog/potm-201211/
"SourceForge is proud to introduce our November Project of the Month, Rigs of Rods. Rigs of Rods is a soft body physics simulator, in which you can build vehicles, and drive them around, and crash them into each other, all in very realistic ways. I recently spoke with Thomas, who is one of the Rigs of Rods developers, and he explained a little bit to me about how all of this works, as well as how you can get involved in this project."
http://www.youtube.com/results?search_query=rigs+of+rods&oq=rigs+of+rods