What I will give you is my personal opinion, others will have theirs. To weld on a car frame a MIG is Plenty strong enough. I wouldn't weld a car frame with a 110 MIG even though they have improved the 110 welder greatly over the years. The frames on cars are made of heavier material (especially the older full framed vehicles) than regular body panels and may require more penetration than the 110 MIG can provide. Some people may come on here and say that they have done it without any problem and that is their opinion....this is mine.
If your going to start out welding up go kart frames a 110 should be strong enough and is a great format to learn how to weld...you might want to start there. Later on you could move up to a 220 MIG and selling your 110 wouldn't be a problem, if you wanted to sell it. I still often use a 110 MIG for body panels, the metal is much thinner than the metal on a frame and the 110 gives me all the penetration that 18 to 24 gauge metal requires.
TIG welding is another matter, before you get into TIG welding, it's probably a good idea to learn how to use a MIG. The skill set for TIG is much greater than a MIG, again, people may disagree and maybe it's just that I'm more comfortable with a MIG but, TIG takes a real steady hand and you need to know how metal reacts when being welded. A MIG will provide you with much of that information before you attempt TIG welding.
I hope this helps and as I said, these are my opinions only.