The latest figures have released regarding the sales of Gran Turismo 5, a PlayStation 3 exclusive. They certainly paint a nice picture of how fast this game is selling. GT5 has seen 6.37 million copies moved in six weeks, according to Polyphony Digital's website.
So how does it stack up to the sales of heavy hitters on the Xbox 360, such as the highly rated, 10+ million strong Halo 3? Jeff Bell, the corporate vice president of Global Marketing for the Interactive Entertainment Business unit at the time, told Gamedaily in December 2007 that Halo 3 had reached over 5 million sales. This was in discussion of sales up to "week of November 18", so giving them the benefit of the doubt, this number had been achieved in 8 weeks after Halo 3's launch.
Halo 3 scored a 94 on Metacritic, Gran Turismo a full ten points lower (It got a lot of gruff for taking so long to release). Halo 3's advertisement campaign cost in excess of $40 million ($10 million went into the creation of the "Believe" ad....can you BELIEVE that? har har.), Gran Turismo 5 never had any indication that would suggest they spent as much or more.
However, there are plenty of other factors that cloud the comparison. The PS3 had a plenty higher userbase when GT5 launched than H3 at its launch (However, other than the heaviest of hitters like Reach, Call of Duty, and Gears 2, not many titles sell that much/fast, and even fewer at the same rate). There will always be the question of "Sold vs shipped" (Though somewhere deep in the blackened hearts of fanboys, they all know all of the big 3 report shipped, as that is SOLD to them). They're different genres.
What's important to take out of this is that, Gran Turismo 5 is holding its own despite critical response from reviewers, less advertisement, and being of the seemingly less popular (of today) genre. GT5 proves that exclusive software on the PlayStation 3 can sell big, perfectly capable of modestly competing with its HD counterpart.