It doesn't matter whether it is a VIN error or not--it is a breach of the agreement of sale to sell you FWD when you were paying for an buying AWD. If it's an innocent mistake on the dealer's part, he would not be liable for additional damages or compensation (e.g., it's not a case of consummer fraud), but you could still rescind the contract of sale due to the "mutual mistake" (both parties were mistaken as to the nature of the car), return the car, and get your money back. If the dealer will not voluntarily accept this, you should retain an attorney to help you.