I got this idea from looking at a mercedes Benz comercial...I am going to to do my best to best describe it...Is simple....

when a car crash and goes over a cliff or there is a high speed collision and the car rolls over, the roof of the car sorts of crumples and gets stumped...What if there is strong rod in the form of a T that goes right in the middle inside the car and connects the inside ground with the roof as support to the roof... That when when there is a car crash the roof of the car will not crumpled in or stumped in or dent in....As a support structure...

That way if there is a car that goes over a cliff there is a great chance of the victim surviving...

if you noticed the arms of the roof of the car are not that strong they are made out of a metal not that strong...

it was just an idea...