(virtually, of course).
I've only seen one DemoDerby. About 8 Chrysler Imperials were entered in various heats. They were indestructable! Something about the design makes the trunk fold up in such a way that it becomes a wonderful battering ram. And the front end is very strong so it can't be killed that way either. Amazing sight. Fortunately, or not depending on your point of view, the cars are banned at many DDs because they're so good.
[link|http://www.geocities.com/motorcity/speedway/1789/secrets.htm|Nick's Demolition Derby Page]
Cheers,
Scott.