Incorrect dash vin tag

We've tried to warn you. I'd be VERY cautious about contacting authorities until you explore other avenues. You may end up with no car or a parts car.

Jump the *** of the seller BAD, and demand he step up. Get him to backtrack where it came from and how. And keep in mind that HE may be THE PROBLEM
I agree with this to an extent. I DO think the OP should contact the seller and demand a refund, re-trade, or whatever would make him whole again. Tell the seller that the numbers are not matching and that it is shady and possibly illegal and that you want nothing to do with it. If the seller balks, tell him you are contacting the authorities and that he is the first person they will talk to. If he does the refund, great. If not, then the Op has a choice. Report or not report. If he reports the issue, he may well end up with NO ca, and the seller could claim ignorance and be off Scott free. As the current owner, the Op would be the only loser. I am a BIG supporter of Police and law enforcement, but I don't know if I agree with @Alaskan_TA 's comment that they will be with him as the victim. Once the car is confiscated, the Op's chance of getting it or his money back are slim, and I doubt if most department's budgets are big enough to spend a LOT of time with a case like this. It is up to the Op. If he has a legal title to the car, he could keep it and drive it or part it out. If he chose to drive it, it is very unlikely that the errors would ever be found out. When the police stop you, they ask for license, registration and proof of insurance. If those are in order, you are good to go. But if I were the Op, I would NOT try to sell it to wash my hands of it, since he does suspect something. AND, of course, he could report it.