Never mind the fact this is basically GT4 HD since most of the cars came directly from that game. We'll see what DLC will bring but there's a lot of badassery missing for the game to be in development for so long.
I stole this feature list from a GAF thread. GT4HD it certainly is NOT.
-Night/Day transition
-Stunt Arenas
-32 player online lobbies
-16 player online races
-Online clan/Clubs
-Spectator mode
-Dynamic Weather (snow, rain, fog, star orbit)
-Ingame weather forecasts not perfect, randomized code PD can't control
-200+ PS4 cars and 800+ standard cars
-Nascar license
-WRC license (infinite tracks due to track generator, codriver really needed)
-Super GT license
-Rolling and damage
-1st person walkabout photo mode
-18MegaPixel photomode
-Stereoscopic 3D photos
-Online photo sharing
-YouTube uploading
-1080p
-PS Eye headtracking
-Motion controls
-HDMI 1.4 Stereoscopic 3D @ 60fps
-Split-screen
-Share cars and upgrades with friends
-Track Generator
-Custom track sharing
-Best graphics in any driving game (lighting, physics driven smoke, attention -to detail..etc)
-Real life tracks recreated in maddening quality (up to 2 year dev times)
-20+ locations with 70+ variations
-PSP Connectivity
-Go karts to Rally to classics to sport to Drag car, ordinary cars...etc etc etc
-Animated drivers, handling and gear shifts, pit crews, tire changes etc
-Custom soundtrack
-Text and Voice chat
-Narrative involvement by popular drivers and Top Gear crew
-Top Gear Test Track
-Open free-form Track Days
-GT Life (career mode, this time with earth map and real time clock) & Arcade mode
-Profile pages
-B-Spec Mode where you manage a team of A.I racers
-Borrow your trained A.I drivers to friends
-In-game (bulletin-board) message boards
-Gran Turismo Video store (Top Gear Show has 350+ million viewers)
-All above on one Blu-ray disc