North America only.

6/7 million, simple reasoning. 

Damage - PD said them selfs its something NA players want and have been asking for.  European and Asian players want more cars tracks and realism.
Online - lack of sunk GT4 sales in NA.  Is a function NAs want more then European and Asian players.
Nascar - a religion in the southern states.  A Nascar games best is over 2 million multi plat. 
Most content filled GT ever.
More supercars and American cars.

With legs little over 2 million. Europe will be easily biggest region for GT5. Over 5 million in Europe is my prediction. Japan should add 500-700k.

~2.5-3m lifetime. Sim racers just aren't selling like they used to in America, and neither are SCEA games. GT5 won't reverse either trend.

bwahaha you're still cracking me up dude. Have you still not learned from your previous predictions?

3-4 mil at the VERY MAXIMUM in NA

I'd say 2.5 mil is more realistic.

Between 4-5 Million, I really expect it to be a big title with 11M+ lifetime

to me, your japan prediction is really too low

between 3 - 4 Million

Somewhere around 2-3 million

700k Japan isn't really unrealistic.  Mingol 5 only did 500k, and Mingol usually matches GT in Japanese sales.

Maybe 500k is bit low but 700k sounds realistic. GT5: Prologue and GT PSP didn't sell that great in Japan. Prologue sold about 300k before it got bundled and GT PSP is currently at 290k. GT4 sold about 1.24milj in Japan with almighty PS2 userbase. I just have feeling that GT is not that big in Japan anymore. Maybe I am wrong...