[mtreis86]

Ah this might be an in-industry definitions thing[1], I was taught most anything thin, especially the pieces that are welded to the unibody, are panels. Not just the outer skin. So floor pan, pillars, trunk panels, roof, subframe, maybe control arms, etc are all panels. Basically anything stamped out of sheet metal. It is the way they're often constructed that leads to corrosion, thin pieces of metal in close parallel proximity are especially hard to clean. Think two flat pieces spot welded together one on top of one another as many seams are. I'm sure capillary action doesn't help those either. They'd have to be sealed in paint or epoxy entirely to avoid the seam corroding. Welding itself changes the structure of the steel and leads to corrosion near the weld. If not spot welded, a different steel might be used for the weld that has higher strength to compensate for welds weakening the steel - but to get that they trade-off higher carbon content, making it more prone to corrosion.

There are very few all-aluminum cars. Audi A8 was for a while and might still be. I am not aware of anything cheaper.

[1] https://automotivedictionary.org/dictionary-of-automotive-te...

[seb1204]

Not lasting forever but car bodies are fully submersed during the painting process and should seal many of the areas you mentioned for a good time.