i dont know if there is a "best" body shell, it's all pretty much about personal preference. if you put your mind to it you could put any mod on any body shell, and it would probably work out fine. what i did was just mod my crappy silver porsche (i have the 4 FF cars and the porsche looked so plain sitting there, so i decided to mod it, since i had nothing to lose but an plain ugly shell

) it's turned out pretty nice, you can lower the front pretty easily and if you cut out the basic spoiler that's on it you can add one of the normal removable spoilers and then it'll start looking like a great car

about the PT, the shape is pretty irregular so you're kind of confined to it's odd shape, and who ever heard of a race modified PT cruiser anyways?