Not in Japan.

GT mainline has traditionally been (much) bigger. I'd say FF as a franchise might be stronger though, compare the handheld FF remakes/spinoffs (FF3, FF4, Crisis Core, Gaiden, etc) to GT PSP

japan is not the world..

I bet GT5 will get at least a 25% attach rate worldwide LTD when all's said and done. Right now that would mean about 8 million sales, but it'll be higher by Summer 2010.

As far as FF sales go, it is.

that's why gt is bigger.. the world is bigger than japan

I think install base affects mostly games with wide appeal, games like MKWii, NSMBWii, CoD, Pro Evolution, Guitar Hero, Madden, etc. Thus, most of these games increase their sales as the userbase expands.

I'm pretty sure if Konami released MGS5 tommorrow, it would sell exactly the same as MGS4, there would be no penetration. That's why we see games like SSBM, FFXIII, etc reach dizzy attach rates.

People are wondering why Final Fantasy being bigger than GT in Japan not relevant?

The OP was brought up precisely due to FF's sales in that region alone. GT is not going to sell to 1/3 the PS3 userbase first week, in any region.

edit: Sorry, it *might* do 1/3 of Japan, I haven't been following it, but it isn't going to outdo what FF did.

when i said FF is bigger i meant FF is more popular.
when someone says RPG people think of FF.

I totally agree with this.  It's partially why PES, Mingol or Musou have toppled in Japan, but MGS and FF have held fairly steady with only slight drops.

I'd also argue that GT casts a wider net than something like FF though.  It has it's hardcore gearheads, but GT's always sold well to the casual/mainstream.  I think it's much more likely to fall into the "tumble" category, though it'll still amass impressive sales.