Gran Turismo 5 is the best!
Learn fastest/racing line in theory and it can be applied in the real world
Test drive your dream car or potential car
Physics are much improved upon GT4
Cons:
Jaggies from upscaled GT4 cars
Poorly built online multiplayer
Slow loading
Slow...very very slow except for the racing
Slow menu, slow access to tuning shop
it's very disappointingly slow
Thoughts:
I really like this game and have used it for its physics and as a real life test drive for all my dream cars. I also gave my own real life car a drive and it's quite similar. Some things this game has taught me.
-old cars have terrible handling(pre 1990s)
-American cars are powerful but terrible handling
-458 Italia is not as it's hyped up to be
-Nissan GTR is a monster
-Ruf(porsche) handles like a dream
-Nascar is fun
-Bugatti veyron is junk