Whenever my mom buys a new car (about every 10 years or so), her thing is to go at the end of the year when they're about to introduce next year's models.
The main drawback is that you may be limited in variety (ie: the only colors available at the point might be basic colors like black, gray, white), but you can certainly get a good price since they're trying to get rid of the cars to make room for the new models (which often aren't much different).
I've heard numerous methods for getting the price down. The last place I went had a no negotiation policy. the price was already where I wanted to pay, so it didn't bother me.
One method is to ask them to produce an invoice for what they paid for the car. Then have them explain what they need for overhead and commission. The place above that wouldn't negotiate actually did that. they showed me what they paid for the car and how much everyone was making on it.
the time before we bought from another place. we spent like 3 hours negotiating. It was the constant, let me go check with the manager and they'd come back with another price. I'd say, nope sorry, that's still to high and it went on like that for the whole time. I finally just got up and said thanks, but no. then they gave me the price I was asking. I probably should have stood up sooner.
the OPs post is usually true. they are much more likely to go down further at the end of a month.
Pay attention to the "MSRP" it isn't the price of the car nor is it close to what the car cost the dealer. They think they at doing you a favor by giving you a price that is under MSRP.
Same with used cars. I go by the Auction Value not the Blue book value.
Car sales could be an interesting study in psychology.
Car salesmen like to put you in "the box" for long periods of time and make you sweat it out. They are usually hanging out in the back laughing at what a sucker they got ready to hand them over a big fat commission. The box can be an office or just sitting out by yourself. I usually walk out. Then they are the ones sweating because they have to keep up with where I am or if I'm leaving. My favorite tactic is when they have to leave to talk to their sales manager, if they exist. They will also bring the manager into the box to explain why their price is fair. I doubt that this person is a manager at all. I stay firm with my price regardless, if there is no deal I want to hear it from them. I haven't heard a car salesman tell me that yet. They eventually come down to earth when they figure out they aren't dealing with an idiot.
I do a lot of research - It amazes me how much they don't know about what they are selling.
I make an offer, in writing and sign it. I'm not trying to fuck them over, the offer is fair and based on all the research that I do.
I stay firm on the offer - Think of Bernie Mac in Bad Santa
The trick to getting the price down is to go in there and be firm on what you want and your price....If it is not met you walk away..So you have to be willing to walk away from the place and understand you might not get what you want. But more likely than not they will do what they can to keep you there.
It also doesn't hurt if you start talking about the Internet sales at other dealerships and their low prices.