To give you the long and the short of it cars like these are not legal for the road and GM/PPG do not want the liability of anything going wrong with the modifications. These are not unlike any other show cars and prototypes.
We were lucky 3 were saved buy donation to the GM collection and the two schools.
You have to remember that automakers can not save everything and for the most parts not all but many show cars are not always up to the level of construction and safety so rather pay a major lawsuit they just scrap the Cars. While some may be road worthy and safe to them most are just a used up business project and by the time they are scraped they are already forgotten.
Case in point most of the Motorama cars were destroyed or so GM thought. Many were cut up but the parts were saved and are now restored. Others were hidden by people in the tech center to be found years later when the climate had changed.
GM even at one time had proposed the X and Y jobs from Harley Earl be crushed in the early 70's till they were hidden away till they were saved. Today the X job and Y Job models two of the first automaker show cars are now priceless.
You have to also consider that cars like this matter to only a small part of the population. But today more attention is being paid to them and more are being save now than ever. Often if they are safe to drive they are being sold off with a Vin now or save tot he GM collection.
It is just part of the business. Even Picasso threw away some paintings when he was done with them or did not like them.
Note I have not followed up on the other three cars but who knows they may still be out there as often cars reported crushed are found. I was the one who found the red one and told Fred. They would not sell it for years but he kept on them and saved it. It is possible one of the others could be hid away somewhere waiting to be found. Many cars though lost are with us today just look at the Bortz collection of Motorama cars.
[This message has been edited by hyperv6 (edited 11-06-2014).]