The biggest eyebrow-raiser with last week's Gran Turismo 6 reveal was that it's launching on the PS3, and not the PS4. Doesn't Sony want to drive PS4 launch sales with one of its biggest franchises?

In an interview on the PlayStation Blog, Sony Computer Entertainment Europe CEO Jim Ryan explained why the latest Gran Turismo isn't debuting on the soon-to-be latest PlayStation, arguing that GT6 can still deliver a significant difference from GT5, despite being on the same platform.

"You had GT1 and GT2 on PS one," Ryan said, "GT3 and GT4 on PS2, then there's GT5 on PS3 and a space next to it. The difference between Gran Turismo and GT2 is unbelievable, but they're both on the same platform. The difference between GT3 and GT4 is huge. We're absolutely confident when GT6 comes, you'll see a big step change up from GT5 too. There's still a lot of potential on PS3 that a developer like Polyphony can really exploit."

The other, obvious factor is the install base. Gran Turismo has traditionally been a big seller, with three of the five main games shifting over 10 million units. To do that, Ryan indicates, you need to have the install base.

"And the other factor is that on PS3 we have an install base of 70 million units," Ryan added. "On PS4 on launch day we'll have an install base of zero units. There'll be plenty of games to help drive PS4 - not least Driveclub in the racing genre from Evolution Studios, a studio with a fantastic pedigree."

A PS4 version of GT6 looks more than likely at some point down the line, and it's something that hasn't shied away from. Speaking to IGN, series creator Kazunori Yamauchi said, "We actually do have a PlayStation 4 version in mind, but for this holiday season, we thought it would be best for users to release on PS3 for now."