FWIW, it definitely sucks to be in the OP's shoes. As a lifelong "car nut", I understand how they are your "baby", and the emotions when it get's effed up because of a careless person. So, I understand why this is such a major issue to him.
However, I do think he missed a fantastic opportunity here. I would hope that even in the emotion of the moment, I'd have had the clarity to let the dealer attempt his "fix", and if I was unhappy in the least, (and it was already going through my mind to jump to another car, as the OP mentioned) I would have at least tried to use my unhappiness and the fact I'm now talking to the GM (bypassing plenty of middlemen) to leverage myself into a great deal on another car.
Worst case, I end up with my old car, in the same boat he's in now. Best case, I turn lemons into lemonade, and I've got a brand new ZL1, or C8 at dealer cost, and a good trade in on my old one without any reduced value b.s. And given the GM was trying to resolve the issue, my bet I'd be enjoying that new car...
