Labelling it a cheat car is a bit extreme and mostly hyperbole, but there's no denying the 2J is dramatically underrated by the PP system. This is something that should be addressed in GT6 but I fear it won't. PD's first foray into altering the PP system was a complete disaster and shows that they have no clue what is wrong with the system or how to fix it and so they'll likely leave it alone. It would be nice if a larger number of cars were competitive in TT's and not just the handful the dramaticaly break the system, would really add to the playability of the game.
The PP system is probably impossible to fix. It's based on a mathematic formula and no matter how you do it it's gonna get screwed up in one way or another, because what it does is that it takes a lot of very different variables and bake them down into a single number to say how good the car is.
For cars with similar variables (size, weight, drivetrain, downforce and engine) it's probably going to do a pretty good job.
For cars with different variables it's always going to fail, in one way or another.
As for Time Trials, there's always one car that is better than the others and this one car will always be in the top. Once in a while it's the 2J, it's hardly any worse than when it's the M3 or the NSX or whatever. As long as the time trials aren't designed so that you must use one specific car to be able to gold the event, I'm totally fine with that.
Well, i think that allmost all the top 100 cars in the last Spa TT where J2 cars, i think that sais enough about the fact the J2 is too good.
No it doesn't. What it says is that all the top players in seasonal time trials use the same cars. It's nothing unique about the 2J, just look at this list for instance:
http://www.mygranturismo.net/rankings.php?sec=3&board=132
Out of the top 250 cars, all but 15 were Lamborghini Murciélago LP 670-4 SuperVeloce '09.
Or this list:
http://www.mygranturismo.net/rankings.php?sec=3&board=116
All but three cars were the Ford RS200 Rally Car.
And this:
http://www.mygranturismo.net/rankings.php?sec=3&board=109
And then look at this list:
http://www.mygranturismo.net/rankings.php?sec=3&board=146
Does the 2J dominate the list? Yes. Is it any worse than the previous lists I shared? No.