Have a look at this article:
http://au.cars.ign.com/articles/744/744294p2.html
This may answer some questions for you all on the body modifications and such. I usually call IGN.com as "IGNore." However, this text is not worth ignoring if modifying cars in this context. Here's the relevant text from this page of data:
IGN: What kind of customization will we be able to see in Gran Turismo HD? Will we be able to see a deeper level of customization than what has been seen in previous GT games? Like, will we be able to tune the aero parts of the car and add vinyls? Or will this newest GT continue to focus mainly on engine and suspension tuning?
Kazunori: (Brings up GT HD's car-select screen and selects a Skyline - which just so happens to fill up the entire screen.) We may not be able to provide this immediately off the bat when we launch, but the cars we are designing/modeling for PS3... you see that line separating the bumper from the body? That (bumper) comes off. Again, previously a car model in GT 4, it was one skin. Now you can take parts off, because the cars are made up of components. So for this Skyline, for instance, you can take off the front bumper and replace it with something else.
IGN: Is the plan to get licensed aero kits like C-West and Mugen? Or will all the aero kits be GT-original designs?
Kazunori: It would be a combination of both, actually.
IGN: Are the aero companies excited to be in the game, or have they even been approached yet?
Kazunori: We haven't approached them yet.
-end
Interesting talk for the water cooler. Again, this goes back to people envisioning that the GT series is moving a bit towards the "Need for Speed: Underground" or "Need for Speed: Carbon" scene. The usual thing people like to do in talking about something is in saying that one concept is moving towards a highly less-favored aspect. As I've argued in the past, is Forza delving into the NFS:U scene since Forza had body kits? Were Forza body kits trying to appeal to the NFS:U types? Not at all. I didn't think that the inclusion of rear wings hurt GT4 in any such way. Those that wanted to (I'll admit) tack on a wing to provide some aerodynamics or to basically show off were free to do so. I've added rear wings to cars to make my pure racers actually look the part instead of going for some sleeper look. I did sort of imagine that I could be more linient in rear wing designs. I'd like to imagine that I could possibly be able to engineer wings to a certain extent. I'm not really talking about the wing choices you have with GT4, but more along the lines of more aggressive rear wings for pure race cars. I was also interested in different styles of wings. I'll show you what I mean in the next paragraph.
Here are a collection of rear wing samples. Where I'm getting at is about the placement of these wings including what type they should be.
This is a touring car wing example: <
http://www.aprperformance.com/index.php?option=com_content&task=view&id=58&Itemid=44 >. Nothing extravagant or outlandish here. It's just a simple rear wing for cars to traverse through the wind at speed. It is a single element package with simple endplates for the rear wing. This is mostly suited to most conventional economy cars that aren't exactly tuned for extremely high-performance applications.
This example is a Grand Touring wing example: <
http://www.slickcar.com/bigshot.asp?ProductID=3159 >. Gran Turismo had a good deal of wings like this one. Only thing I would likely complain is that these wings aren't like some of the real race car wings. Maybe I'm so concerned since there were some racing wings that didn't really seem like pure race car wings. And it wasn't like I was going for a rear wing like on the Australian V8 Supercars or even the Aston Martin DBR9 on something like a Honda Civic or a Suzuki Cappuccino or anything.
This is a drag racing wing example: <
http://showoffimports.nl/customer/product.php?productid=18392&cat=258&page=6 >. The wing in the link is the This would greatly suit high-speed cars as you get a low-profile wing capable of keeping your car stable in high-speed races on high-speed courses. This kind of wing configuration would be pointless on a very slow road course since you don't want to have a drag-style setup on a twisty road course.
Now the links below are more of what I call "engineered" rear wings. I'm talking about those made through wind tunnel research and actually look the part of pure race cars. So take a look at how the rear wings are designed:
http://www.rsportscars.com/foto/05/dbr905_05.jpg (Aston Martin DBR9)
http://www.rsportscars.com/foto/01/focuswrc06_04.jpg (Ford Focus RS WRC - 2006)
http://www.rsportscars.com/foto/03/imprezawrc06_14.jpg (Subaru Impreza WRC - 2006)
http://www.ultimatecarpage.com/pic.php?imagenum=9&carnum=450 (beautiful blue Saleen S7R)
http://www.motorsport.com/photos/lemans/1994/24h/lemans-1994-24h-jl-0104.jpg (Nissan 300ZX GTS - 1994(?))
http://www.westcoastpromods.com/homepage/06/may/members/delehay.jpg (Pro-Mod Dodge Viper Drag Car)
http://supergt.net/supergt/2006/06team/06teams_e/06t062.shtm?dt (Willcom Advan Vemac 480R)
http://supergt.net/supergt/2006/06team/06teams_e/06t013.shtm?dt (Endless Advan CCI Z)
http://supergt.net/supergt/2006/06team/06teams_e/06t088.shtm?dt (JLOC Lamborghini Murciélago GT-R)
http://supergt.net/supergt/2006/06team/06teams_e/06t036.shtm?dt (Open Interface TOM'S SC430)
All I'm getting at here is about a variety of different wing packages for street cars and highly-tuned street cars made for racing. It took me a long while to come up with all of this. Hope it was all worth it.