In the vein of old airplanes with fabric covering, there is a BMW prototype I didn’t miss the first time it was shown in the news. The designers built it so the body could change shape. What really seems to happen is that the edges under the fabric move.
It is an interesting idea, but I think they’d have problems making it crashworthy. If it were crashworthy, the fabric outside would only being adding unneeded weight to the car.
I think it would be far more useful to have modular cars where significant sections could be swapped. A traditional trunk could be swapped for a lorry bed, for example. It is already done for the roof of convertible cars – I don’t see how making other sections convertible would be any different.