Interesting new patent from GM. It's listed as "morphable body moldings, rub strips, and bumpers".
GM is using a "shape memory” alloy, which expands when heated, to remove minor dents, and claims to have had best results with an alloy of nickel and titanium that changes state at around 70°C. The alloy is mixed with filler particles of electrically conductive carbon, so that feeding a current through the material makes it heat up and rapidly change shape.
The alloy could be placed along the edge of a car door, an area that often suffers knocks as people climb in and out. When the door opens, a low current would flow through the strip, making it expand slightly. As it closes again, the current switches off, cooling the strip down. Should the door have suffered a bump, the expanding alloy ought to absorb any dents as it shrinks back to normal.
The patent is listed at this link: http://www.wipo.int/ipdl/IPDL-CIMAGE...IME=1128789019