http://www.gtplanet.net/secret-menu-reveals-more-tracks-in-gt5-prologue/

Just when you thought you’d explored every nook and cranny of GT5 Prologue and finally laid the game to rest, it’s back from the dead with one more surprise up its sleeve: a super-secret “Special” menu. As revealed by @Mathieulh on Twitter, the Special menu gives you access to lots of hidden features. Notably, it shows several more tracks in the game such as the Nurburgring Nordschleife, Circuit de la Sarthe, and Tsukuba (though they can’t actually be selected). You can make all the cars available, create a race and specify the make and model of each of your opponents, tinker with visible menu options, and more.

Admittedly, there aren’t any major bombshells here – especially since we already have GT5 in our hands. However, this may be how some kiosks and demos were running “GT5 Prologue” versions of the Nurburgring and La Sarthe (perhaps they’re accessible with other codes?), and it is frustrating to imagine those tracks may have been on our Prologue discs while we were waiting for the full game.

To see the menu for yourself, go to the Prologue’s options and scroll down to the “Miscellaneous” category. While holding down the R1 and L1 buttons, press the following:

DOWN
RIGHT
RIGHT
DOWN
RIGHT
RIGHT
DOWN
RIGHT
RIGHT
DOWN
RIGHT
RIGHT

Next, press the START button, and the “Special” category will appear below the Miscellaneous. To see the menu in action, here’s a video. Don’t bother attempting this in the full version ofGT5. It doesn’t work, but there may be a similar menu hiding in there, somewhere…

Note: What would you like to be open with secret codes?? Let's help Kazunori Yamauchi makes the overhype became overdelivered... and by the way I love Gran Turismo...

Forza options will be well received, but no trolling please (and i don't fell the need for just cosmetics changing)

But that is GT5 Prologue... the OP was wrong.

The OP is for what you think it should unlock

So what do you think should be a hidden option in this game?

Most misleading headline of the week.

Thanks for the compliment, but if GT5P serves as standard there is a nice chance that it will be present in full version.

Hummm... now I understand you.

So it's probable... the online lack some basic options and I believe that some hidden already but just a new patch will unlock them.

Let's hope it only get better by the time.

Considering how bad the rewards are in GT5, I'm think somethin like this wouldn't be a bad idea at all.

It doesn't help that there's a huge lack of events too. I've barely finished all of the earlier events because there's really no incentive. The credits, xp, and car rewards are all horrible early on and some of the cars in the dealerships cost ungodly amounts. The car rewards really don't get any better later on either. I can understand that PD wants us to work for them and plenty of hardcore gamers would normally appreciate this approach but if you're a car collector, you're gonna be doing a serious amount of grinding in the Extreme Series.

Beisdes all that, I'm actually surprised that the option to race against any car you want isn't already in GT5 though. I find myself occasionally going into Arcade mode to race just for fun but the options are pretty lacking.

Uhnnn I played since GT1 and they were always a game were you have to play a lot to progress... I don't think they have casual player in mind, wich is a problem for the people that want just to hook up and drive a monstruously powerfull car...

But yes, there are a lot of places to upgrade.