So I decided to make clear list of all that missing stuff. Mekanaizer Add it to your first post if you want.
I'm sure it's not a full list, so if you have something to add tell me.
Cars
Toyota FT-86 Concept II
Desc: Trailer on GT TV
Source:
http://www.youtube.com/watch?v=cNC7boHn0LA
NASCAR 2009 cars
Desc: Seen in E3 2009 trailer
Source:
http://www.youtube.com/watch?v=l2uQ2ayvvWY
Mini Cooper S RM
Desc: The official name was MINI Cooper S '07/Tuned...(Seen in SEMA Off-Screen Gameplay) (thanks to GT-R_EMOKID)
Source:
http://www.youtube.com/watch?v=fU_QkfWIyVk
Tracks
Test course
Desc: Seen in Spec 2.0 intro
Source:
http://www.youtube.com/watch?v=okJyGEGpQds
El Capitan
Desc: Seen in Red Bull leaked trailer (footage from GT PSP intro)
Source:
http://www.youtube.com/watch?v=TyN-O3HiJ78
Ice Arena
Desc: Seen in Red Bull leaked trailer (footage from GT PSP intro)
Source:
http://www.youtube.com/watch?v=TyN-O3HiJ78
Piazza del Campo
Desc: Playable in demo that was available in some stores and seen in official karting trailer.
Source:
http://www.youtube.com/watch?v=tHx-eDMEz2Q
Top Gear Test Track wet/time change
Desc: Available in IB-1 license test. Wet track and different time of day. In replay tarmac is dry and sun is missing.
Source:
http://www.youtube.com/watch?v=E4Pjwsc8Cs4
Course Maker Themes
Mountain Road (aka Stelvio Pass)
Desc: Seen in Toyota Ft-86 Concept trailer
Source:
http://www.youtube.com/watch?v=lFhZZRFcxPU
Mountain Road 2
Desc: Seen in Ferrari California Trailer (was it official?)
Source:
http://www.youtube.com/watch?v=08svLVxcT0k
All course maker tracks with weather change
Desc: In Spec 2.0 it was able to see rain at Mt. Aso (not other effects), rain/snow at Eifel and Tokyo Bay karting themes (cloudy at Eifel) and rain at Liege (dark sky). All available online (but without control of weather). Also Toscana tarmac theme is available in rain in Rally Special Event. It featured reflections on road (removed in 2.0) and shiny tarmac, but with online bug tarmac looked dry.
Phot travel / Other locations
Credits to StephanCTR (
https://www.gtplanet.net/forum/showthread.php?t=181212)
Wind tunnel
Desc: Seen many times, featuring various cars
Bonn
Desc: From GT5P. Also featured in start screen in GT5.
Kamakura
Desc: From GT5P. Also featured in start screen in GT5.
Bad Neuenahr - Lennepark
Desc: From GT5P.
Nürburg
Desc: From GT5P. Also featured in start screen in GT5.
Tokyo
Desc: From GT5P.
Underground garage
Desc: Seen in various trailers
Source:
http://www.youtube.com/watch?v=cNC7boHn0LA
Warehouse
Desc: Seen in Apex Book and GT5 start screen with tuned cars.
Pit scene
Desc: GT5 start screen featuring only premium cars.
Top Gear studio
Desc: Seen in movie about Top Gear special challanges
Source:
http://www.youtube.com/watch?v=sIKmcoAfaeo
Red Bull garage
Desc: Seen in movie about Red Bull X10 challange
Source:
http://www.youtube.com/watch?v=lFhZZRFcxPU
Dockyard
Desc: Seen in Toyota FT-86 Concept trailer
Source:
http://www.youtube.com/watch?v=lFhZZRFcxPU
"Studio" backgrounds
Desc: black background with smoke and powerful lights, and plain white background. Seen in trailers and GT5 start screen with old race cars.
Features
Point to point Course Maker tracks
Desc: Seen on pre-release GT5 screens
Bloom in photomode
Desc: In Spec 2.0 bloom in photo mode was present. After 2.01 it's gone. (photo by jBhIpS)
Open/close roof
Desc: In California trailer we can see stock Ferrari with and without roof. In game we can only close roof by adding aero parts.
Source:
http://www.youtube.com/watch?v=08svLVxcT0k
Notes:
All of the above were somehow connected to GT5. I'm listng stuff from GT5P missing in GT5, stuff from GT5 trailers and screens (for example El Capitan is from PSP but featured in Red Bull GT5 trailer), and stuff seen in game but not available to use freely.