Originally Posted by WVOtoGO

Yes. You are correct.
But that’s not what automotive safety (in a crash) is all about.

Think about the two vehicles and the wall again:

The 3K lb vehicle hits a solid wall at 20 mph. It is a vehicle designed to absorb the impact. The front crushes. The engine ejects (thanks VW) out the bottom. Airbags deploy. Etc. etc. X number of G forces are experienced by the occupant for Y number of seconds as they decelerate to a stop. They live.

Same wall. Same speed. But now a 6K lb vehicle built solid as a rock (like those cars in the 50s/60s). This time, the deceleration rate is way too high. Very little kinetic energy is transmitted from, or absorbed by, the vehicle throughout the deceleration process. Way too many Gs for way too long of a period are subjected to the occupant. They die.

One step further:
It is quite possible that if these two vehicles were to have a head-on. The occupants would fare the same fate. The occupants of the larger mass vehicle succumb to the loads of the initial impact (Do some reading up on dynamic overshoot and the related. Good stuff.). While the occupants of the lower mass vehicle get knocked backward from the point of impact, but live.

- Shelby