The list of variables needs to be collected and entered in the first place; for a new game I'd assume that the number of variables would go up. For GT6 it could go up significantly depending on how realistic PD wants the game to be. They might also make multiple models (for example leaf spring suspension and coils) some of which might not be ready for Prologue.
Well... maybe. This gets into the whole game development cycle issue, but I'd think that if a Prologue was ready, the physics and dynamics work for the game was pretty much done.
But I do expect that PD is working to model those components more accurately and individually this time, given the fast ram and abundant processor power available in PS4. Then again, if they're making it for PS3, the improvements won't be as dramatic or involved, but I still expect some. If nothing else, bodyroll should be back in which we had in the previous GT games, along with some better tire modeling. Damage, I don't know, but I'm not too fussed about it. In every area though, I expect improvements in all areas. If they have to drop resolution to 720p to enable proper particle effects and shaders, I hope they bite the bullet and do it.
And on the content for a potential Prologue, of course it will be limited. It'll be like an "episode 0" of a new show, and prologues have never had all that many cars and tracks. GT5P was quite the exception, and even it only had a handful of cars and tracks to keep us entertained for a year. And by all indications, Kaz was trying to get GT5 wrapped up by 2009. Jordan was even shown a release schedule for holiday 2009 by SONY officials that had GT5 for release by December 2009, and produced an article for it that had us all in a tizzy for it, but it obviously didn't happen.
I don't expect anything like this for GT6 because there was a small global tantrum when we learned that GT5 had been delayed indefinitely. Even the three day delay in November 2010 caused an uproar. Delays are par for the course with Gran Turismo, but I expect them to be much shorter from now on, and Kaz talking release when they're more sure about it.
Anyhow, to heck with this net stuff, gotta race.