It depends on the collision. A car crumpling in on itself will only be safer at low, to intermediate speeds when hitting other cars, or objects that crumple in on themselves; the type of collision you'd see in a city. The purpose of the crumpling is to reduce the shock on the human body. In the case of a high speed collision, or one including a larger vehicle though, the car crumpling in on itself will probably kill you. (not that the shock wouldn't if the car didn't crumple in on itself)

All that said, if you're in a collision, you should try and get yourself off the road, a safe distance away. That's for pretty much every situation, but is especially important in low-visibility conditions, or if your car is on fire