I've seen this in Sydney, Australia, person I did work for a long time ago built a house that looked like a commercial building. It was on the side of a hill, he couldn't drive into the first floor, drove onto the second floor under a canopy then had a four post hoist with a steel floor that lowered the car to the first floor which was his garage. He drove off the hoist and parked. Collected Jags and Rolls.
It might be an architect's nightmare and expensive but could be done. Four post hoist would cut down on space with the working parts underneath it and just four posts to the top. Posts would be a little wider than the biggest thing you might put down there. Could even have a rotating center on the floor of the hoist.
Just a thought....
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