The clearcoat on my 1991 BMW-Diamantschwarz-metallic 318i has flaked off a large part of the center of the roof. Likewise, the clearcoat on the engine hood is pretty much shot too; it is still there but appears to be delaminating from the paint. All this comes about from being parked outdoors for all of its 18 years. I am not looking to fix the paint job up too fanatically, but would like to make it better than it is. Is there a cheap way to make a (relatively) attractive repair to this damage? If it costs more than about $100, I'll just leave it the way it is and claim its thermal damage caused by reentry into the atmosphere from outer space. Sandpaper? Spray cans?