Article by Larry Hayden, Hayden's Auto Accessories.
Just imagine this:
You drive your car onto a round platform surrounded by glass. Then you get our of your car and walk to pay for your parking ticket.
Then, whoosh, (OK, so it is only a slow whoosh), your car descends on a round elevator to locate in front of a vacant space deep underground in a circular hole reminiscent of a missile silo!
Then your car rides a few inches off its wheels on top of a narrow metal plank and gets inserted into the parking place. When you return for your car, you put your parking ticket into a slot, and, whoosh, the car elevator descends, extracts your car from its parking space, and brings it back to the surface. Here is a picture of the "missile silo" : http://www.digidunia.com/awesome-car-parking-place-in-japan/
And here is a video showing a man going through the whole process: