BEFORE you sign they will bend over backwards to do whatever it takes to get you to sign.
AFTER you sign, you are on your own, aside from the warranty.
You need to inspect every inch of the car. The paint.. Is it free of 'orangepeel? is it evenly painted. (Some of the blue candy was poorly/unevenly painted, Check for scratches. tiny dents. check it in bright lighting. If the have it outside in the dark, or covered in snow. make them move in inside! At least into a brightly lit area.
Check hood, doors, hatch/trunk movement. are the seams OK, any wide or bits hitting on doors, hood, trunk/hatch?
Look at the wheels, any dings scratchs? Check the glass for scratches. The roof. If you have a moonroof open and close it. Check the seats, do the move OK? the steering wheel, move it around up down in out. move the electrical mirrors. try the parking brake.
Look at the interior seat fabric or leather, for marks, cuts, bad seams.
When you test drive it before you sign!! (they may say you have to sign first. no way. you get a test drive BEFORE you accept it. Check how the tranny behaves. Check the parking brake by leaving it on and trying to move (gently! just see if the car sort of bunches up.. do not drag the rear wheels!)
Check how the steering feels, the gizmos. scroll through the left steeringwheel screen. (in between speedo) Scroll through the right steering wheel screens (middle of dash screen) try various buttons in middle dash.
Make the salesman connect your phone to the system for you !!!
ANd show you how ,and make them show YOU so you know how to do it yourself.
When you are on the 25 mile test drive.. yeah make it more than a few blocks. This is $25,000 you are spending.!!
Check the handling and more than anything check the transmission behavior. See if it makes you happy.
If no problems then sign.
If problems you HAVE to get them IN WRITING to say how they are going to fix whatever, and the manager or service manager has to sign it, not the salesman.
Then.. after all that, sign.
If there is clear physical damage. walk out.
If they do not want to allow you a pre sign test drive walk out.
If the ywill not bring the car to a brightly lit area, walk.
Tell them you will come back when you CAN see the car and make the inspection and test drive.
Hope it never turns bad.. and you get a great car.