Neat concept. To get around the rain bit you could possibly give the driver an option to use the upper part of the door as rainshield instead of retracting it into the vehicle.
Another possible problem: a cupholder in the door...
---LOL, I was going to ask if you found this while using the search term "making dents in car door dissappear", but then I saw that it was almost a month after your dry ice post.
---That's cool, but I wonder what HP motor(s) would be needed to incorporate that into my Scouts... lol. Scout doors are very* heavy.
