I put a plug on it and tried it out on a couple pieces of 26 gauge galvanized (duct metal)
1) It's pretty heavy and awkward to hold, get in the right spot and pull the tirgger.
I was doing it out in the open on the floor, I can imagine how hard it would be to do it in an awkward spot on a car body.
2) It only makes a spot about 1/8" or less in diameter.
3) It's very trickey to get the tips adjusted properly.
I tried to pull the two pieces of metal apart but they were welded together pretty darn good.
Still need to try it out on a car body but I know from using my 120 volt one, both sides of both pieces have to be very clean and pulled tightly together mechanically because you can't (shouldn't) use the welder's tongs to pull the metal together.
Also keeping the tips adjusted and dressed clean is something we have to do pretty often on ours.
Gotta go find a tough place on some old car to try it out on now