If you can get 220 to wherever you're likely to be welding, get 220. If you don't think you'll be taking your welder to other places, it's the only way to go, IMO. The cost isn't that much more, and if you need to weld thicker stuff, that flexibility will be rewarded, and if you ever decide to upgrade welder-wise, you're basically set until you find something that requires 3-phase
I assume we're talking MIG, anyway. In most ways I'm a Miller Electric guy... But I have a Lincoln SP-175 MIG welder, and I have to say I love it. It's a little guy that you can throw in the back of a truck, but it's been rock-solid dependable to me (I used it extensively in the construction of my shop) and it's a bit cheaper than the nearest Miller welder. If their smaller welders are as good I wouldn't hesitate to recommend one.
Also, don't even think about using flux-core wire on a car. It's way, way, way too hot for most materials on a car, unless we're talking armored car, then maybe... Even then, only if you subscribe to the
"the bigger the glob, the better the job" philosophy.