Understand your situation
I was reading this thread because I am in a similar situation. You are right. According to insurance companies and state DMV's that work with this, a bent unibody it a damaged frame. I am also from Colorado. I guess I can impart the information I found out this morning. According to Colorado, if a frame (or Unibody) is bent it is called Frame Damage. This frame can either be fixed or not repairable. If it is frame damage the car must be listed as a salvage title. At that point, the owner can then, if possible, repair it enough to pass Colorado inspection (or insurance company inspection). The car then becomes a built from salvage. If a car is salvage it is under a salvage title. If it has been rebuilt it must be permanently stamped in the inside of the door, and must state so on the left hand corner of the title. If a dealer sales you the car, according to the DMV, they MUST tell you and give you the appropriate papers. Based on what you have said, if this car was listed as frame damaged, and if all frame damage puts a car into salvage (which I would assume you could verify with your insurance company and/or DMV) and what my insurance company and the DMV have told me is true, and the auction did sale the car as "frame damaged", and you have proof the dealer would have had that information, then it appears the dealer has indeed done something wrong. It also would seem, something slipped through the cracks. Do you have a regular title, and why isn't it salvage title. The DMV told me to check on my title and see if it said rebuild in the upper left corner. Look on yours. I now have a car fax, and mine suspiciously shows it titled in Maryland 6 days after the wreck report of the police in Colorado (at that time titled in Colorado). Then 2 weeks later titled back in Colorado. All I know so far about my situation, is that the frame (unibody) is buckled, is not repairable, and somehow the title was never changed to salvage or even rebuilt. And that the dealership said they got a car fax (which they gave to me) inspected the car and fixed everything. I have been told by another auto repair shop, that they know the facility, and that there wasn't anyway for them to not know, because of how they inspect the cars. I'm at this point collecting all the info I can from insurance company, police accident report, and DMV to see what to do next. I don't know about the law, but whether or not you did all the due diligence!, if the dealer knew about frame damage, especially if that frame damage would legally make it a salvage or rebuilt, and didn't tell you, then his is morally wrong, and based on the info I have been collecting, possibly not following what he is required to do as a dealer. What you did or did not do, does not effect whether or not he followed what he is suppose to do.