Buying a 2012 Hyundai Elantra, and saving $1000 off of MSRP.
I sent an email to all the dealers nearby telling them that I know that the invoice price is this, and I am willing to pay this price.
Every dealer rejected my offer, but one accepted. Therefore, I went to the dealership and signed the worksheet with the price I asked for. It seems that they know that when a customer says that they know the invoice price, they cannot negotiate down. They can only reject.
CarCostCanada.com really helped in the process by providing the information required to get the best deal. I have no complains about using your service again.