I was surfing around and I came across this...
http://www.playstation.jp/scej/title/gt4/main.html
...which appears to be the Japanese site for Gran Turismo 4. I'm not sure if this is a complete list, but it seems to be official anyway. Like the other GT games, there's an eastern bias to the cars that are available, but they do have some cool American cars such as
-Buick GNX '87
-Cadillac Cien '02
-Chevrolet Chevelle SS 454 '70
-Ford GT '05
-Plymouth Cuda 440 Six Pack '71
-Saleen S7 '02
to name a few. They have a Pontiac Vibe, but no Firebird/ TA or GTO? That makes me a little sad, but oh well. There's also a section where you can listen to some sounds. They have clips of the engine starting, engine revving, and horn honking for a Skyline GT-R (R34), a BMW Z4, and a Corvette C1 Convertible.
http://www.playstation.jp/scej/title/gt4/main.html
...which appears to be the Japanese site for Gran Turismo 4. I'm not sure if this is a complete list, but it seems to be official anyway. Like the other GT games, there's an eastern bias to the cars that are available, but they do have some cool American cars such as
-Buick GNX '87
-Cadillac Cien '02
-Chevrolet Chevelle SS 454 '70
-Ford GT '05
-Plymouth Cuda 440 Six Pack '71
-Saleen S7 '02
to name a few. They have a Pontiac Vibe, but no Firebird/ TA or GTO? That makes me a little sad, but oh well. There's also a section where you can listen to some sounds. They have clips of the engine starting, engine revving, and horn honking for a Skyline GT-R (R34), a BMW Z4, and a Corvette C1 Convertible.