I have an older Hobart 120? (small 110v mig), and it works really well on 3/16" and thinner steel.
I have welded 1/4" with it for some brackets, and no problem as long as the edges are beveled so you can get into the steel. I have an old stick welder for heavier stuff.
Anyhow, any of the good Brand name welders (Hobart or Lincon) work well for car hobby type projects, just spend the extra money for the gas setup. The flux cored wire leaves more spatter, and I think larger in diameter than the small solid wire. Anyhow when I tried using the flux core wire it was more prone to burn through thin sheetmetal, but it is OK on exhaust tubeing and brackets.