Research and patience are your best friends when car shopping. And they're your only allies during a high pressure hard-sell.
You have to know the car/truck you want inside and out ... what's standard, what's in each package, what's optional, and (depending on when you buy) what's coming next year. Visit several dealers and test drive the one you like at a couple of them. Shop the competition too, but leave your checkbook at home and don't sit down to deal, you're not ready yet.
Before you ever sit at the table, do all your financial homework . Find out what other dealers are asking and what you can afford. If you're not paying cash, get prequalified on a couple or three loans and pick the best financing. Lendingtree.com is great for this ... one app gets you 3 offers.
Now're you're ready to sit down and deal. Pick the dealership you liked best and go at the end of the month. Don't be the first to name a price unless you lowball ridiculously below the invoice. Don't tell them what you're pre-approved for or you'll end up paying it. Keep the salesguy on topic about the vehicle price as optioned, compared to last year's model and compared to the competition. Bring up every defect or problem with the model that the competition does better. Anything to justify a lower price. Get a list of all dealer surcharges and have them calculate tax on the whole amount.
If you can't get the price in the ballpark or if your BS-o-meter goes off, stand up, thank them for their time and run for your life. In fact, even if you do agree on a price, go for a walk or a drive anyway. Take your time and think about it. Get some dinner and talk it over with the s.o. There's no hurry. There will be other cars an another lot. And if the offer still sounds good with food in your stomach, go back and sign.
Use your own financing. Get everything in writing and read all extended warranty or service plan paperwork to make sure your vehicle options are actually covered.
Or you can get a GMID and avoid all this hassle
