Unless Scott is lying to us, which I STRONGLY doubt, there is only 1 silver car and 1 red car. These concepts easily cost $1m plus to build. Its unlikely and uneccessary for GM to dump a bunch more money into additional concepts.
However, I read a little blurb yesterday from Charlie (Z284ever on Camaroz28.com) that the chassis has ended up being largely carryover from the current GTO/VE Holden, meaning its very possible that production is way ahead of where we all suspect, OR that more mules have been built on top of existing GTO chassis for driveline testing, etc.
Its a good guess that Transformers Camaro is built on a GTO chassis.