after looking at some car dealerships, I would still apply tile cement with a trowel. I am not a big fan of self stick in general but, if you are going to drive a car on them, I would want as much adhesion as possible. When you turn the wheel when the car is at a stand still, you will pull up the tile if it is not cemented down!
Also, I believe the cement would help with any leveling that may be needed.
I would also apply a sealer to keep water from attacking the seams.
Good Luck, Jason ps.. Make sure you hit the breaks before you get in the garage!