Now that vehicle moving through z-levels is possible maybe it is time to implement moving grabbed vehicles up/down stairs? At least single-tile ones like shopping carts. Would be quite a time-saver, both in-and out of game.
Dragging stuff up and down stairs is dubious. Dragging stuff up and down ramps is something that should be possible (it kind of is, you just need to finesse some bits) and I need to work out the last details.