Unfortunately that's just the way that GTA IV (and all other past GTA games) seem to spawn cars - it spawns a bunch of copies of cars that have already loaded, sometimes making them take over the whole map
I don't know if this mod works with the latest patch, but you may want to try it out if this multiplayer issue is bothering you: http://www.gtagaming.com/downloads/g...misc-mods/1953
. The Hellfury, etc aren't included there, but you can check out the modified values for the cars mentioned, then apply those to the cars you want to see more often.
Edit: sorry, just saw the "PS3" in the title, obviously can't mod it then. Yeah, not much you can do - that's just how it goes! The aim is to make load times / lag lower for the user.