Given how long it purportedly takes to render a car model at Polyphony standards�about a month for the PSP version and up to six months for the PlayStation 3 versions�one can see how five years quickly passes.

Polyphony plowed ahead, creating a fleet of 800 cars for the PSP version, some of which are "reduced and streamlined" from their PS3 versions, with more than 30 real-world tracks on which to race those cars.

According to Yamauchi, the PSP version of Gran Turismo is a "fully specced" entry in the ten-year-old series, telling Kotaku that "no matter who plays it, they'll know immediately that it's a Gran Turismo game."

"I want to stress that it's not a subset to the series," Yamauchi said, despite there being "limitations" to the PSP's hardware specifications. In fact, it one-ups previous Gran Turismo games by letting players trade and share unlocked vehicles with other driving enthusiasts wirelessly over ad hoc mode.
One hurdle that Polyphony Digital is dealing with right now is designing the PSP iteration for two platforms: the original PSP and the recently announced PSPgo. While the internal hardware may be largely identical, the feel of Sony's new, smaller PlayStation Portable is noticeably different. On the PSPgo, the analog nub controller has been relocated and the buttons have been redesigned. The new hardware has a cross-pad controller and face buttons that feel more digital, with a tighter click to them than on the original.

"If you want to play on a PS3 controller," Yamauchi responded, "you'll have to play Gran Turismo 5." That also means no support for Logitech's Driving Force GT wheel. It's PSP controls or nothing.

The PSP game will take advantage of the PlayStation 3 in another sense. Gran Turismo PSP one of the titles that will support Ad Hoc Party mode, letting gamers use the PS3 as an ad hoc server, taking the PSP experience online. Ad Hoc Party software is currently only available in Japan, but Sony Computer Entertainment America reps say a domestic release is in the works.

But what Kazunori Yamauchi and Polyphony Digital focused on was welcoming new players to the series�and sticking to a solid 60 frames-per-second presentation.

Kotaku - Gran Turismo Creator Explains PSP Delays, Talks Controls & Online Play - E3