I think its pent up anger and repression that leads to this hostile behaviour when driving. People are anonymous in their cars so the concepts of "proper" social behaviour and politiness go out the window... selfishness, ego, and everythign else come into play.

Rush? don't be fooled... we arabs have no concept of time ...  it is all about ego...  who got the bigger errrrr...

I spent the lsat two weeks driving around Europe.  New roads, with just a GPS to help.  Not once have I felt nervous!  I just wished I could commute every day to work with such calmness and ease... 

no ego issues, coupled with thoughtfullness for the others and respect for oneself and the law...  ahh...  am gonna stop dreaming and get back to work!