Gran Turismo 6 is hitting the PlayStation 3 worldwide on December 6, although (as Sony announced at a press conference Monday) it'll be reaching stores a day earlier in Japan. When Famitsu asked producer Kazunori Yamauchi how far along the game was at this point, he couldn't help but laugh a bit in response.

"It's something that I get asked in every interview," he replied. "It's really hard to give an accurate answer to that. The basic components are already complete, so overall I'd have to say about 80 percent. The physics engine, the steering controls; those parts of the user interface are things that we fine tune-right up to the very end. Things like the game modes; I can say that those are complete."

Among the more interesting recent GT6 announcements: The game will link up with smartphones. "We can have a forum system in the game and have gamers use that to communicate each other," Yamauchi explained, "but unless you go back home and turn on your PS3, you have no idea what's going on. That's a pointless time lag to have, isn't it? It'd be better if you could use your mobile device to see what's happening with your friends and community. Someday I'd like to try making the game playable on mobile devices, but we're starting out just with community tools for now. Technically it's possible, but it'll be a gradual sort of thing."

Most gamers last saw GT6 in action as part of the GT Academy demo released by Sony last July. Yamauchi told Famitsu that the game's physics engine has already been upgraded from that demo, and that this engine is inside the playable version Sony plans to show at the Tokyo Game Show floor starting September 19.

Yamauchi also addressed the idea that Gran Turismo often "feels" a lot different from other driving sims in action, pointing out that the physics engine could have a lot to do with that impression. "We develop our physics engine based on the results of all the test measurements that we make," he said, "but it's not necessarily the case that these measurement results are always going to be the same as actual driving conditions. What's more, even now there are still a lot of things that happen to a car in motion that we don't fully understand. In other words, there's room for imagination in this genre, and I think the part of any game's physics engine that's more 'imagination' is what makes one sim feel different from each other."

Is this physics engine going to be shared with the Gran Turismo 7 that Yamauchi's team at Polyphony Digital are presumably working on now for the PlayStation 4? Yamauchi said that would be the case, going on to suggest that to him, at this point, hardware platforms don't matter quite as much as they used to. "The PlayStation 4's large memory size is a unique trait," he said, "but in terms of CPU performance, the PS3's Cell chip, while difficult to handle, is really capable. They both have different advantages. Besides, I think the online community aspect, one of the most fun parts of GT, doesn't have anything to do with the platform. The PlayStation 4 game which we'll likely call GT7 will be done in about a year or two, I think, and I think the community aspect's going to be vital there as well."

The TGS event next week will be GT6's final major public showing until the December 6 release date. "We're devoting ourselves to two forces in GT6," Yamauchi said. "One is honing the internal mechanics of the game, the physics engine and user interface and so on. Another is pushing the title's external energies, trying to help it break out of the shell of the video-game industry. I'm hoping that everyone is looking forward to seeing what efforts we're making on both fronts."

Correction: This story initially misreported which console the game is coming to on Dec. 6. We apologize for the confusion.