so why cant forza 3 do the same ?

I don't think thats true. It has to do something that sets it apart from everyone else. GT was the first sim on a console(I think?). GTA 3 was the first of its kind. Halo was the first FPS and the xbox flagship game. So unless Forza sets itself apart from other games I don't see it getting that kind of fanbase. It doesn't affect the overall quality of the game though. I just don't think releasing loads of sequels means that it will become a big franchise. Rachet and Clank is an example. I'm sure there is others too.

ioi said 400-500k first week for forza 3 is the likely number, so we will see

Forza 2 launched with sales of around 300k from memory. I remember back then that was considered to be a HIGHLY successful launch.

Yes Forza 3 is rating better, yes the Xbox 360 has a larger installed base.

But not enough to generate anywhere near a three fold increase in sales.

if they bundle it, then it might, thats how foza 2 got to its very high numbers, although it sold respecitvely well before it was bundled

in case i wasnt clear: Why cant Forza 3 be bundled like Forza 2 ?

It have to outsell Shift first...

Forza 3 will do 500-600 k with europe and us aligned most sales will come from america i think sales will be 20-30% better than forza 2 it will sell 5-6 million LTD by the next console cycle.

GT5 will sell about a million or maybe slightly more. It will end up with a LTD of 10-15 million
Remember guys gt4 sold 14.89 million, according to polyphony

I thought GT4 sold <10mil.

GT3 sold 15mil?

Two words: NO WAAAAY