Hello to both Lancer and DarkAzn, welcome to the Planet. John M. of Houston, Texas, USA. So I understand we have kits and online gaming being mentioned. Let me try to tackle both topics with my critical and even comical commentary.
KITS
I'm surprised no one said "WTF are you thinking? This is Gran Turismo, not Need for Speed: Underground (this is getting killed to death on here)" yet. The only kinds of bodykits I think will work is racing modifications (still unconfirmed as of yet). Think about it. Being able to tune a car with aerodynamic parts to make it a race car, granted your car performs like one to begin with. Mentioned in "Gran Turismo Resorts," there is the probability of a Paint Shop for GT4. I don't know if you can paint your Toyota Altezza in Reflex Spice or not, but the game will allow for custom paints if bodykits are denied. Don't expect to see APC, WingsWest, or anything like that being represented. Most you'll probably get is racing parts from the manufacturer. Aftermarket stuff I don't know about, with a "Tuning Village" also possible. Personally, Tokyo Xtreme Racer 3 had the best options in terms of bodykits and aero parts. You build up a car piece-by-piece. You then pick the material you want to use, be it FRP, Urethane, or Dry Carbon. If you ask me, if you have a fully-tuned street car, why not make it a racer? It's pointless to have a street car with all the goodies just be relegated to looking stock. I'm sorry. I just don't see that happening. I want to convert my car (even if it's a cheap car) into a road racer or rally racer. I don't want to carry the same stock apperance as in GT3.
As far as online play goes, it looks like online play will make GT4 better. But I'm not the online gaming type. You don't judge a game as good just because the online play is great. A game has to be good TO BEGIN WITH before judging online play. The only exclusion is Super Smash Bros. Melee for GameCube. You play up to 4 players at home. That's enough excitement to rock the house. Gran Turismo 4 will be fun, don't get me wrong. Just that, I don't think online play will make the game any better. It will be fun, but you don't buy a certain game for online play, but only if the game doesn't REQUIRE multiplayer (like Half-Life Counter-Strike).
There's my mind. Speak yours. And by the way, yeah. Use a search, even if you aren't sure about what you want to devote a thread to.