[sixtharmy]

I have a bunch of small hail type dents in the roof of my metro. I tried a variation on the hot/cold thermal shock dent removal method a month or so ago. Waited for a 102 degree day with my dark blue car parked out in direct sunlight. I believe I could have fried an egg on the roof. I placed several small rubber collars about 2 inches deep over several hail dents. Since I had access to it, I took a thermos full of Liquid nitrogen and filled each collar. It took a minute or two for the N2 to vaporize from each collar and as it was doing so I could hear the metal popping and booming. I repeated the treatment a few hours later after the sun had reheated the metal. Sadly, I could'nt see any reduction in the depth of these small dents.