Good engineering will go a long ways toward establishing safety in our vehicles. I have seen some pretty scary engineering at car shows over the years. So when I was building my coupe, I tried to identify inherent weaknesses and compensate for them as best I could. My gas tank, which is in the trunk, has a 5/8 inch plywood box glassed into the body on three sides that separates it from the passenger compartment, and I built a bar that is welded to the rear frame which is hidden by the rear fascia to keep a minor fender-bender hit in the rear from caving the body halfway into the trunk. But like Jack said, no hot rod is going to be as safe as a modern vehicle. We just have to do our best to make sure they are not un-safe.