All we know is that it was "minor" fender damage. That could cover a lot of things. A fender can be easily dented from something other than an accident, so depending on what this looked like it may well have not given any clear indication that it was from an accident. If the OP could not tell from that damage that it was actually caused by an accident rather than something else and the OP relied on the dealer's statements about what caused it and that there had been no accidents then he may well have a case for fraud. I have little sympathy for used car dealers who cross the line from puffery into fraud; all too many used car dealers do that. So unless the damage was so obviously from an accident that any person who is not expert in cars would see it was from an accident, I wouldn't let the dealer off the hook for his/her misrepresentation on an argument that the lie was not material (which is basically where I see you going with this).