Originally Posted by Beaverboy
Unibody production cars have very complex crush zones engineered into them. Space frames do not. Sure, the frame might survive but your innards will not. On a race track there are far fewer solid objects to hit and there is never oncoming traffic. Frame survivability is not the same thing as safety.
It depends on the space-frame.
An OE space-frame like a Fiero, or more recently an NSX probably has as much crumple zone as a similar-era unibody.
The only difference is that the body is removable from the space frame, where a unibody has the skin welded on, for one less layer, and a little bit of additional surface rigidity in the metal skin.
A Space-frame, however, is much easier to re-body and repair minor damage, or offer multiple styling options, and also easier to build in a garage by bolting the body on. A space frame can be anything from a tube-frame chassis, to something very similar to a unibody, minus the outer skin surfaces. A Monocoque is similar, except that it is made out of fewer pieces, and highly unitized under the body, like a structural 'tub.'
The amount of crush zone in the space-frame depends on on how it is designed and implemented.