the biggest one is polish.
GT is made by polyphony digital.
the head of GT is a perfectionist.
from the sounds of the engine, and the weight of the cars everything is recorded and tested by the studio with real cars and it shows when compared to other racers
also GT is a name in the sport itself, companies come to GT to show their cars because they trust the quality the put in the game.
the other is sony give a huge budget to gran turismo, their studio have actually access to the cars and they even make a REAL car with citreon design by polyphony and many their own nissan skyline.
they also design the graphical interface of the nissan GTR.







