Hey, Damien, in reply to your notion that if you were to, "hit a car head on at 30mph and you was doing 30mph that would be an impact of 60mph."
It’s an interesting fact of physics that two identical objects on a collision course with each other and travelling at the same speed don’t experience double the impact damage.
Each object encounters the forces their own particular speed predicts as if the other object it had collided with was stationary.
A statistic thoroughly tested by the program Mythbusters.
Nick