Justin mentioned it needing to be a certain year or newer a couple of iterations of this ago. I've never seen that in the rules though. Seems like I gave a number to someone that owned a mid 90's Subaru and that worked.
The competitive vehicle doesn't need to compete with what you are buying, it just needs to not be a GM. You can own a Prius or an F350 and use that VIN when buying a Vette (examples just provided as the most opposite things from a Vette that came to mind). You also do not have to trade in the competitive vehicle. You can keep it, you just have to own it and have it registered.
As I recall I looked up a C7 last time when someone asked about it. I built out a mildly optioned Z51 and it was something like 8-10k off sticker with the employee discount.