@Rockhead,
Not only finance your purchase, but at very good interest rates. Argue with the manager of the car dealer until you get a deep discount on the retail price plus don't pay more than 1.9% interest. Depending on the car, some car makers are discounting their cars by over 20%. Use this as a basic guide for your purchase. .
If they won't let you have your price, just say "thanks, but no thanks," and begin walking out of the showroom. If it's too low, you know they can't possible sell you the car for that price, but don't be surprised if they chase you out of the showroom to tell you "okay." They're real hungry now. Use that as your tool.