This one seems to be pretty common. I can't see how recycling steel has anything to do with rusting. Steel rusts when the iron combines with oxygen. It's called oxydizing and it is common to lots of materials. Fire is the result of fuels combining with oxygen, it's a natural process. When iron ore comes out of the ground, it has had plenty of time to combine with oxygen and it is probably as close to pure rust that you could imagine. The refining process that eventually produces steel for your auto panels rids the iron of impurities and compounds in carbon to produce steel. It's this process which determines the quality of the finished process and recycled steel is probably better raw material than iron ore.