If you have the time and initiative (and can be willing to walk away without a car) you can get a good deal.
Go in to a dealership, haggle a bit, and if you don't get the price you want, say "OK, I'm going to go out and do some more shopping... here's my card, give me a call if you change your mind". Apparently just the threat of walking away will sometimes prompt some movement, and if you do walk out, you'll sometimes get a call the next day with a better offer.
I think they key is that it's not a bluff; you actually have to be willing to get up, walk away, and go look at something else.
That is key, most of us don't have that.
More on how dealers make money is here http://www.edmunds.com/car-buying/where-does-the-car-dealer-...
* pre-select make, model, color, options, etc (this way I'm comparing apples to apples)
* find various examples meeting my criteria on the market from different dealers/private sellers
* get initial offers from all the dealers
* get financing in-place - either cash or an approved car loan from your bank
* Whichever dealer has the lowest price, call the rest and say "dealer X has beaten your price by $Y. I have cash in-hand and I'm ready to buy today. Can you go lower?"
* Depending on the answer, either cross that dealer off your list or update all the other dealers with the 'new' lowest price.
* Rinse and repeat until nobody goes any lower, then go buy your car.
Dealers hate that method, but it's saved me thousands of dollars with each car purchase regardless of new or used. Ignore all pleas for 'financing', 'what do you want your monthly payment to be', etc. You're going for the absolute lowest price you can wrangle. As far as time investment, outside of figuring out what make/model/options I want and securing financing from my bank (or getting cash), the 'rinse and repeat with the lowest offer' method has never taken me more than a weekend to implement.
Sitting in front of a salesperson who, if they aren't an extrovert are at the very least required to act like one, for a few hours while they see just how good of a deal they can make for themselves and their boss by talking sounds like a spot of hell.
It's only marginally better than being stuck to someone like that on a plane; at least when buying a car, you can walk out of the dealership.
I think one problem is that people get wedded to the car before they go to the dealer, are too excited to be totally rational, and get swept along by the salesman. Being introverted might be an advantage.
Because when you don't have that info, the dealer performs a simple calculus - how likely are you to walk away after 3 hours of haggling over $1000 that you didn't know was negotiable. The answer is probably pretty small, on average, and thus it is worth it to them to not go rock bottom on the price.
If I can pay a service to get that rock bottom price (where price + service charge < my negotiated price) why would I not want to use it?
I don't think buying a new car makes any sense anymore. At one time, when cars started to fall apart after 50,000 miles, it may have made more sense. Today, when with routine maintenance almost all new cars will go 200,000 miles or more with few major problems, it isn't a good deal. Let someone else take the depreciation hit.