When you actually count them Forza 4 has more cars from regions outside of Japan then GT5. So please, tell me exactly, how does that make GT5 more diverse in car selection?
Just make your count... GT5 have a little over 400 unique cars (removing older year models, tuner cars, rally versions etc).
And GT5 have 99 manufacturers.
Companies like Amuze, and Spoon don;t count. They do not manufactur cars, but tune them. Eliminate all tuning companies and it's 75 or something. I just counted, and I included small manufacturers who contribute 1 car to the game, like Homell.
Edit, and only 400 unique cars? LOL Then why have 1,000 in the game? How many Nissan Clones do you need?
Forza rarely includes older models of identical cars, uqually they only have them when there are huge differences in design (The original M3 only had a tad over 200hp, now it's 414, you definatly need more then 2 M3's). So of the 600 cars, I bet 500 or so are unique, and the only ones you really eliminate are race cars, and different models of cars, with minor changes (like there are 2 NSX's, one for each generation, but both are nearly identical in spec).