Then again, we basically didn't go to a dealership other than for test drives. We e-mailed every dealer within an hour and a half of us with "This is exactly the make and model we want, these are the options, this is the color (but we're open to substitutions), what's your best price?" We took the lowest bid, and if there was any funny business (there was with one), we walked.
Most dealers now have online sales departments that are setup for these low-overhead but low-price transactions (this was a rarity when I bought mine in 2009). Apparently the sales guy we bought from sells 3x more cars than the next-best sales guy at the dealership, because he knows how to price the cars to move online and then acts straight & efficient when the buyer comes in.
He held up his end of the deal, paying 18% interest on a massive truck loan for 3 months.
The sad thing is many people would do the same thing without the ability to pay it off in full. At that interest rate and a ~7-10 year loan term, you'll be upside down on the vehicle until the very end of the loan. And most people wouldn't keep the vehicle that long because something else changes in their life...or they just want a newer vehicle.
I did my house shopping the same way. For some reason realtors are a lot better about negotiating the actual sale price than car dealers are. I never really had a realtor try the "So, tell me about your maximum monthly payment!" pitch on me, probably because you're expected to have your financing lined up before you shop.
If you're going in to buy something with a "max monthly I'm willing to pay" in mind, you are setting yourself up for a really bad deal.