Forza Motorsport 3 week 1 sales were 470,692 according to VGChartz
If your using weekly sales ending October 24th, 2009, then of course Forza Motorsport 3 only sold 246,536 units, but this was before the game was even released in Americas, and only accounts for 2 days of EMEAA sales, and 3 days of Japanese sales.
If your blatently going to ignore Americas week 1 regional sales simply because the game came out a week later in Americas, thats just making an unfair comparision.
Fine for me. Also consoles should be compared launch-aligned, then.
But, how will you know exactly how many copies get included in the console bundle?
Also speaking of bundles, GT5 will be bundled with the console at launch, and in Japan they get that damn sexy blue PS3. My prediction for 1.5-1.8 million units is for non-bundled units.
Bundled copies aren't trackable precisely, unless manufacturers or developers release their data.
About your prediction, I don't know, GT4 did around 40% better than that with a starting user base twice as bigger, but for GT3 we have weekly data only for Japan, and just there it did more than 550k 1st week with a PS2 user base in Japan that was just ~4.4M, while now PS3 is 5.7 there, and what's more, PS2 WW was around 11M when they launched GT3 in the rest of the world, while PS3 is more than 38M WW now.
I guess also that the choice of the new launch date could change GT5 first week quite wildly, a reliable prediction is almost impossible.
I think you read my other post in "GT5 will fail...." for that 40% better. GT4P sold 40% better then GT5P in Japan, and it was released only a year before the launch of GT4, where GT5P had 2 years.
As for user base, I don't really corrolate sales with user base. As Halo shows, Halo 3 had a 40% attach rate, but Reach only has about 12%, and it's still selling better. Early into a consoles life, there is little to no competition, and games have long periods of time to sell. Thats why I think GT1 and GT3 sold better then GT2 and GT4.
The only attachment rate arguement I make is that GT1 and GT3 sold better then GT2 and GT4, and GT5 is being released late into the consoles life, like GT2 and GT4. Also with PS3 total sales likely to be about 2/3rds PS1 sales, and half PS2 sales, it would be substantially more difficult for GT5 to sell as well as prior GT's. I mean GT's on PS2 did outsell GT's on PS1 generally, so I expect GT5 to sell 1-2 million worse then past GT games.