Why does it take so long to buy a car? I'm not talking about looking at cars or finding out which one you want, test driving, and so on. I'm talking about once you get down to brass tacks, it takes forever to get out the door once you decide on what you want. You first have to go to your regular salesman. Then he sees what he can do. He brings over a ringer, whose sole job is to get you to buy a car and get the most money out of you in the process. Then the ringer will bring over a manager, because after all, the ringer can't do anything for you other than wear you down. The manager may approve it, or he may decide that you haven't been raked over the coals enough. If that's the case, then you go through the whole process again. Finally, after you get approved then you are only done with the process for the car buying. Following that you have to go through the same punishing process again to get a loan (if you decide to get the dealer financing) during which they try to give you something where they can add some more money. After that there's the old add-on process. You know, do you want to have undercoating, rust protection, etc, etc. After that, and only after that then you finally get the keys to your car. All in all, even at a luxury car place, it's a good quarter of a day process. At a regular dealer, you may have to pitch a tent and pack lunch and dinner.
The only thing that is in the favor of the consumer here is the dreaded walkout. George Costanza legendarily threatened it at David Puddy's Saab dealership, but to no avail. Even if you want the car that you're going in for you have to have alternatives so you can threaten the walkout. Otherwise they know they've got you and you're out of luck. It's best if there's another dealer in the area, but sometimes that isn't always your choice.
Seriously, it shouldn't take longer to buy a car than to buy a house. While I love how my dealer's service department has been, it took a long time to get that darn car. If there was a place that would let me buy a car in the same amount of time as it takes to go through Costco, I'd shop there in a heartbeat. I want to get in and out quickly, not take all day going over the particulars of the car as I repeatedly am worked over.