I think it can be modified...not sure how.Maybe these?
minRunOverSpeed = 2; //how fast you need to be going to run someone over (do damage)
runOverDamageScale = "5" ; //when you run over someone, speed * runoverdamagescale = damage amt
runOverPushScale = 1.2; //how hard a person you're running over gets pushed
Change the quoted 5 at runoverdamagescale to 0(without quotes)
But it would cause that you can`t ram people anymore...