Buying a 2008 Mazda MX-5, and saving $3000 off of MSRP.
Offered 3% over invoice and got it. 0% financing. Then $500 grad rebate. Invoice price was slightly different than posted on this site. A couple hundred dollars less.
Offer 3% over invoice and ask to see their invoice before confirming the number. Make sure their number is the same or less than your 3% over invoice cost before confirming.