I think I found a bug in physics calculations. I don't know if it can help, but the only way I can describe it and explain is to attach this replay. Please observe the "paweusz" car (3-rd pos. on start). It is thrown away a few meters forward and totally destroyed.
http://195.20.3.254/p/somethingswrong.mpr
http://195.20.3.254/p/somethingswrong.mpr