Regarding the "needle scaler" tool, I did a bit of searching online for examples of using one on car parts.
The summary seems to be it is good for removing larger matter from most hard surfaces. Possible examples might be all the thick dried grease/oil/dirt/crud build up that you always find on the lower crossmember, suspension arms, etc. Removing sound deadening on the interior floor or undercoating on the bottom pans. Getting the majority of rust and grease and crud off engines, trans, etc. As a preliminary cleaning before sandblasting (greatly reduces the contamination of your blast media) or other cleaning processes (easier to finish clean things with solvents, etc). It's also reported to be great at cleaning up welds, but I'm not sure what type of weld process that's referring to - some need it more than others. Rust removal is a common use but only on heavier metals; they are too aggressive for thin sheet metal. However some people have successfully used one with lower air pressure to remove body filler and rust on some body panels (although I suspect that was on vehicles with thicker sheet metal than our Fiats have). There are places on the X where the sheet metal will hold up to a more aggressive approach - such as removing rust from windshield channels or such. But it might also be good at removing all of the excessive seam sealer Fiat globbed all over the X's body. That stuff is like undercoating or the sound deadener inside, it's difficult to remove with traditional hand methods (one example is prepping the seams on the bottom box tunnel before removing it to replace the coolant tubes).
Cast iron and steel materials seem best suited. But it can be used on heavier cast aluminum if the air pressure is turned down a little. It looks to be particularly good at getting into nooks, corners, crevices, around cast lettering, bosses, seams, curves, etc where a typical scraper doesn't do well. While it does remove a lot of unwanted material, the resultant condition of the surface depends on the substrate; rough surfaces like cast iron may still have some very light contamination in places, while smooth steel plate surfaces come out very shiny and clean. So depending on what you intend to do with finishes you may still need to do some final prep work. But it appears to be a time saver getting to that point, especially on heavily contaminated items.
I'm wondering how it might compare to other methods for doing such tasks? Pressure washers do ok for some things with heavy grease build up, but have their downside and limitations. Various blasting processes work well for many tasks but can get very messy and costly. Solvents and brushes work for many items but is time and labor intensive. Wire wheels on power tools seem to do the same result overall, but they are not as effective in all those tight places the needle tool gets to.
All in all it strikes me as another tool option in an arsenal of weapons to use when attacking a restoration job. Much like the multitude of various grinding tools I have for metal fab work; each is great at certain tasks, and having a choice of them to use together makes the work much easier and less time consuming, but no one tool can do everything. And who doesn't need more tools?
