GT5 prologue was bundled alot later after release

also that time PS3 was expensive when PROLOGUE launched so they bundled it for free

now PS3 is cheaper and so they would bundle it just like the GT4 PS2 bundles where they make money on bundle HW and SW

I dunno, I think they'll do it like the other bundles... premium priced, but with a bigger HDD offsetting that.  The game's still "free" in a sense then.

Also, if Wii has launched without Wii Sports packed in it'd have probably been $200.  And still profitable. Like it was in Japan.

Alright, time to crush this attach rate argument here...

The obvious problem with comparing GT3's attach rates (now) with Halo 3's attach rate, is the massive amount of PS2's sold after GT3 was no longer being bought. To solve this, I'll show you specific dates in which GT3 had already sold most of its copies (with not too many PS2's sold):

Week ending August 19th, 2001: Japan's GT3 sales at about 1.7mil with 5.5mil PS3's sold, or a 31% attach rate. That's close enough to the current userbase of the PS3, so if GT5 is a hit / still popular there, we can expect at least 1.5mil from that region.

End of March 2003 (see page 31): Over 11 million copies of GT3 were shipped by the end of March 03. Since under 2 million were shipped to Japan, we know that at least 9 million were shipped outside Japan, so... That's over 9 million GT3 copies shipped to ~35 million PS2 consoles sold (VGC), likely close to a 25% attach rate in the west.

Attach rate really doesn't tell us much, since there are too many outside factors (like PS2's extremely fast rate of consoles sold), I don't think it's worth putting that much weight on.

As for other factors:

While people have mentioned Halo's popularity has constantly been increasing, the same can be said for Gran Turismo. Although the second title per console always performs worse, the first of the console (GT1, GT3, soon GT5) performs well. The exception here is European sales, which increased with every release besides GT2. Expect GT5's Europe to be nearly on par with Halo in America.

The increased competition (such as Forza 3) may mean less GT sales, but the same can be said for Halo. CoD is surely the bigger franchise out of the two, yet people think Halo will still do fine. I think the same will probably happen for GT5.

Bundles. I have no idea how many American copies of GT3 were sold due to bundles, so this could hurt the past sales' arguments for GT5 by quite a bit.

As for my prediction? I see GT5 selling at least 1.5mil in Japan, 3 million in America, and 5.5 million in Europe, which would clear 10. I just don't know how far it can go after that, though.

Your Japan figure is WAY too high.  GT4 barely cleared a million in Japan, GT5P only sold about 250k (300k were bundled a year later) and GT PSP only did about 250k also.  

Honestly, I think GT5 will be lucky to break a million in Japan, 1.5 would be an insane turnaround for the series there (even GT3 came just shy of 1.5m), where it's been in clear decline (mirroring Mingol almost exactly actually).  More realistically, I think it'll do between just 700-900k.

The highest selling MGS is MGS1/Twin Snakes with 5.63M. The lowest selling main GT entry is GT2 with 9.37. Not completely double...but I mean, the highest selling one was near 15M.

It would appear GT5 fans are not happy that it has been announced only 200 cars are actually proper (premium) cars, the other supposed 800 have been ported from previous versions.

http://www.neogaf.com/forum/showthread.php?t=398721

For a game in development for so long that is pretty lame really.

Wonder if after reading that people still think it is going to beat Halo's 11m sales as seems a lot of pissed off people!

Wait... Neogaf people that appear to be pissed over something?

Talk about a revelation.

It has been revealed that those 800 or so other cars will still have cockpit view.  Just not the authentic ones like the 200 premium cars.  As usual, people are making a big deal out of nothing.

That is not what they are saying. They are saying basically the textures have been imported from PS2 and slightly touched up. If you look at the link in the first page your see a picture of the premium and standard ones. Acording to gaf there will be no cockpit view from the 800 and all will have windows tinted and have different damage physics. If you look on page 2 your see some clever people have managed to get some screens and the cars clearly have "Gran Turismo 4" written on it.

Now most of us me included probably couldn't give a monkies, but to die hard racing fans it is a big deal. Especially when you compare it to say Forza 3.

GT3 was just shy of 1.5mil?

Well, I'm using VGC figures, since I'm too lazy to get anything else. Are you looking at Famitsu / MC / w/e else?

And if you don't mind, what site are you using in particular? Seems you always have the numbers right on hand.

Also, since Japan is a small factor in the success of the latest games' sales, I don't think it'll hurt the 10 million(plus) chances much.

Problem with your logic is both games will be bundled. How do you figure out bundled and unbundled sales? Ioi will know but he won't tell us. Kinda hard to say, like would Forza 3 even be over 2 million had it not been for heavy bundling and discounting soon after release? We don't know.