Man ya'll all confused the heck out of me reading what ya'll have done for out of state purchases.
I've bought 4 cars out of state...never have I paid taxes upon pickup of the car, 2 of them were from dealers too.
I go down to my local DOT office/courthouse were you normally pay your registration and title transfer fees and ask for a 10-day temp paper plate.
You take the paper plate with you to get the car.
Exchange the money and get the clear title....drive back with title and paper plates on the car.
Then when you go to transfer the title to your name at your local DOT/courthouse, thats when they collect the sales tax.
Some states make you have a bill of sale stating what the sales price is, while other charge the tax based on the blue book value regardless of the real condition of the car. Also depending on your emissions laws, you may have to get the car emissions tested first before you can xfer the title.