another big part of Gran Turismo are speed physics. The realism and simulation is great but going 150 and looking like your going about 50 is confusing at times.
I didn't think GT4 was that bad in this area (certainly better than GT3), but the ideal solution to a poor sense of speed is to allow the user to adjust it themselves (by allowing them to adjust the "field of view," measured in degrees).
The sense of speed is one of those subjective things that will vary from person to person, and even from TV to TV.
I have a new one. You know when you are buying every parts for your car? You have to go into a every single parts and select "buy", etc., etc. How about just check boxes, then select "buy"? I timed myself buying every possible upgrades for my car, one time. I believe it took around 4 minutes!

Waste of time.
Ah, yes. Gran Turismo syndrome...
Game: "You have chosen 'Sport Exhaust.'"
Me: "Okay."
Game: "Would you like to purchase the 'Sport Exhaust?'"
Me: "Yes."
Game: "Are you sure?"
Me: "Yes."
Game: "$5000 will be subtracted from your credit total."
Me: "Okay."
Game: "Are you sure you want to buy the 'Sport Exhaust' for $5000?"
Me: "Yes."
Game: "After parts are purchased, you may choose to install them."
Me: "Okay."
Game: "Would you like to install the 'Sport Exhaust' on your current car?"
Me: "No, I was just going to hang it in my virtual garage and admire it...YES, I WANT TO INSTALL IT."
Game: "Are you sure?"
Me: "YES."
Game: "The 'Sport Exhaust' has been installed successfully."
Me: "THANK YOU."