As I have said before, I don't think we know much about GT4 drifting. We have no real idea as to where we'll see any drifting action nor did anyone ever talk about it. If some of our GTPlanet insiders have a chance to catch up with PD representatives and key people behind GT4, perhaps we'll find out what will make it into GT4 as a drifting track. But I have a feeling that that Autocross track would make a big track for drifting. But until then, drifting is about as neglected as almost most other things about the game (based on the media and certain critics).
No one builds drift cars. Cars are not exclusive to drifting. You can only tune to drift. This is as long as you know your "drift settings." Among some of the names, Signal Auto has to be one if the big names in not only tuner cars, but also drifting as I have seen the two S15 Silvias in pictures before. But don't forget, we're getting some tuner machines. With some of the rear and four wheel drive machinery, it should be worthwhile to find a way to drift all of them. But if I had to suggest a nice drift car from GT3, I have two. The first is the FD3S Mazda RX-7. If you have cash to burn, you can get the Ruf RGT. Why did I choose the RGT? With Drift settings, it's a very nice machine to use enabled when you unlock it in Arcade Mode. In fact, while it has "Drift" settings, kind of serves as a Grip car as well. Kind of think of it as a "do it all" Drift Car.
But still, we know drifting is going to be like the D1 Grand Prix, but no photos or extra information has been made available. Or maybe it's all going to be shown off in December (which for me, means Finals and college Bowl Games). Never tell...