A 220v wirefeed is THEE most efficient machine for auto work.
It will handle anything from thin shettmetal with .024 MIG wire and up and more than 1/2" with multiple passes
I wrote this on another forum in the welding and fabrication section,it pretty much gets to the point of facts,not myths....
As was already said,a 110v machine will push it to it's limits and borderline that "maybe" it'll work and hold welding 1/4" without a preheat.
once you start gettin into alot fab work on the Jeep you'll runnin into alot heavier things to weld than a 110v machine is designed for..heavy suspension parts,roll cages,heavy bumpers and rock gards,motor mounts if swapping out for more power..etc etc.
A 220v machine is just so much more versatile and suitable for Jeep mods and repairs than a 110v,there wont be anything on a Jeep your working that a 220v can;t handle without question,from thin sheetmetal to heavy axle tubes and chunks.
Now a days there really isn't that much of a price difference in my opinion between a 110v vs 220v to justify going with a 110v unless 110v power is your only option,but that would be a rare occasion unless you live in an apartment and have no 220v dryer plug.
You'll most likely hear/see some people say"i welded my whole rig up with a 110v 140 amp machine and its held up to the worst abuse in the world!"...that's all cool and i'm glad it held up,but it still doesn't hide the fact that a 110v machine was put to it's limits and overworked at max settings to do the job,plus it doesn't hide the fact that it may of made a nice looking weld but the fact is it still aint hot enough to do a confident sufficeint weld on thicker materials.
The manufacturers recommend the maximum thickness of steel for the machine not for the fact it can't get a complete fusion in every pass,but for the fact it isn't hot enough of a machine to sufficeintly penetrate that thickness.this is where most don't understand...i could weld up a 1" thick plate with a 110v and cut it and it'll show a solid complete fused weld,,but do a bend test on it and see what happens because it didn't penetrate because of the heat sink the bigger steel caused and sucked the heat from the weld..
Bottom line is..when picking a weld machine for a purpose..the general rule of thumb is to purchase one that is designed to handle more than what you ever plan to use it for,for the fact you won't have to geuss if it will hold,plus you won't be working the machine at it's limits and seriously shortening the life span of the machine.