disappearing car doors.....

That always seemed like a neat idea.

It's a great idea and seems well-engineered here. My family and later I, drove a 1974 Chevrolet Caprice Estate wagon with the disappearing tailgate. It worked great and was a much better design than the ones used now. Unfortunately, this great idea was eliminated after 1976 because of downsizing and designs that couldn't include this feature. A real drawback and an example of regulations interfering with good design and popular features.

Quite cool; but, something else to go wrong and need repair.

Cool idea, but seems like it would be difficult to exit from an accident.  Major Jaws Of Life action.