We bought an 07 Honda Pilot a few months ago.
Step 1: Used our super credit rating to get a blank check pre-approval for financing from Capital One.
Step 2: I emailed several dealerships in the area and got their lowest internet price.
I went to this website:
http://www.carbuyingtips.com/car4.htm
and downloaded this spreadsheet :
http://www.carbuyingtips.com/offer.xls
I then looked around Edmunds to get invoice, holdback, factory to dealer incentives, etc., information.
Step 3: I took the lowest offer to the dealer closest to my house, whom I didn't get a quote from, and told them to beat the lowest offer and get my color. They did and we got $6,200k off the MSRP, ~20%.
Step 4: I told them if they could beat the rate on the financing, they could finance my purchase. They beat it by a few basis points, so that helped them make a little money.
Step 5: I told them if they gave me a fair price on my trade in, I'd sell it to them. Otherwise I'd just private party sell it. It was a fair offer based on work needed to be done on the 6 year old vehicle and my hassel to sell it and the tax credit I got on the net new purchase price.
Done and done. The happy wife has her new gas guzzler.