[jyl]

On overall safety, the Prius wins hands-down.

For demolition derby/figure-eight purposes (repeated collisions for entertainment value), I don't care.

For a real-world collision, the Galaxy car has the advantage of mass but the Galaxy's occupants have the disadvantage of lacking restraints, airbags, engineered crumple zones, passive safety. The Prius car has the disadvantage of mass but the Prius' occupants have the advantage of restraints, airbags, engineered crumple zones, passive safety.

Since I'm an occupant, not a car, I'd rather be in the Prius. (Or other modern high-safety car.)

This isn't a simple "matter in motion" physics question involving billard balls. I think that is the point you're not getting.

It doesn't matter how much damage the car sustains, and the relative acceleration is only one factor. What matters is (1) does the passenger compartment remain unbreached, and (2) are the occupants restrained from motion/impact within the passenger compartment.

The crash videos illustrate this pretty well. In the 1960s crash tests, condition (2) is failed, terribly so, but as the occupants die from massive blunt force trauma, ejection, incineration, etc I guess they have the satisfaction of knowing their car might be reparable. In the Prius tests, the car is a write-off but the occupants survive. Including the head-on with a SUV.

Edit: Sorry Jim, I'll stop posting about the Galaxy/Prius crash stuff. I guess we got badly off topic.