I have read your posting, but there was a ....

serious flaw in the argument. The formula used in your posting F*t=m*V is correct. However, t(time) is limited for all cars. You cannot build a car with a unlimited length just for surviving a crash. F basically is proportional to how hard/soft the car is. If you build a soft car, you will need a long front section to absorb the momentum in the crash. But usually the length of the car is defined by other design factors like the engine dimensions(FR/FF cars),the wheelbase, and the physical appearance,...etc.So if we fixed the t(time), the F (hard/soft) only depends on m(weight) and V (design speed). If both the soft car and hard car are designed to survive a crash at 40mph, the F only depends on the weight of the car. That is why I mentioned in my original posting that the heavier car is harder. If two cars both are designed at the same speed and the weight is the same, the hard/soft will only depends how much crushing zoom they have in the front. If you need more acturate calculation of the relation of Hard/soft, weight and speed, you can use the formula F*s=1/2*m*V*V, where s is the length. It is the same formula as the F*t=m*V. Just use t=2*s/V to replace the t(time). I think you don't need to post another article since I already explained everything here very clearly.