first off, do some homework; find out what the dealers get their inventory for, you can try kelly blue book or edmunds. once you know that it makes it a little easier to figure out what would seem like a good price to bargain with. depending on trends and whats hot and new will weigh heavily on the prices of the car. a good rule of thumb, but not really a rule is say about 800 over inventory price. yet again it varies depending on trends, like if they are getting rid of the previous years or if the car is like the newest model. as far as talking to the dealers, they expect it, and if you don't talk it down you'll feel and will be screwed. just have some confedence, they need your money more than you need the car. just remember it's your cash and only you have the power to give up how much and how little to a dealer. hope this helps, yet again, none of this is really a rule just a good way to not get ripped.