I have painted and done a lot of work with cars, obviously I prefer a paint booth with a normal spray gun....but you can paint with spray paint, it turns out ok really, but it requires a lot of work basically. One thing to remember it will only turn out as good as your body work, take the extra time sanding and preparing. I have painted fenders before, you can get the spray paint that has a fan pattern that helps, paint small areas at once also, say the top of the fender, break it at the trim or something. Let it dry for a day then wet sand and buff it, you can get it really nice if you work with it.
But....if I were going to do a whole car, and wanted to save money....I would just spend the time preparing and sanding and then just carry it to one of those cheap auto paint places and pay the 150-200 bucks or whatever it is now. Might be a little more expensive but you would be hours ahead in time from the spray paint route.