Theres a bit of confusion going on here, drift cars as pointed out by Stevisiov are tuned to drift, by that I mean the suspension and drivetrain are adapted to allow the car to oversteer very easily but be very controlable at the same time. The cars in the TT are not drift cars, they are setup for the track. Now any track car is setup not to oversteer, it will oversteer if you push it like any car but it's primarily setup for maxinum grip, break that grip and the control you have is next to none!
Ok the locked diff......it dosn't have a locked diff, thats something you'll find on 4 wheel drive vehicles when straight line traction is needed off road, what it dose have is a limited slip diff........something many of you with mid to high powered cars have on your own vehicles and it's desighned to give more power and control in the corners. Or if your jeremy clarckson it's there to create smoke whilst shouting "POWER" LOL
The whole issue of good physics = the ability to powerslide or do perfect donuts is wrong.......unless you've specificaly set your car up to do that.
One last thing is you need to look at the speed your doing when you sudenly lose the back end.......The fastest speed I've done and lost the back end was at 65mph...it was in a Gen 7 fwd 190bhp celica going round a long sweeping corner and it happend because the rear tyre suddenly dumped about 70% of it's preasure....I held it but it wasn't a hollywood moment!! If I'm playing about with the backend on my 330 it's usualy between 20mph-40mph.....well within my meger skill.
If you just check out these videos you'll see some of the worlds most talented drivers can't "catch" or hold an unexpected oversteer moment on the track!
http://www.youtube.com/watch?v=l1aq_F9QzPQ
http://www.youtube.com/watch?v=Sfb4G44_e1w
http://www.youtube.com/watch?v=GXubxGXy3IA
When you look at most racing crashes they are caused by either 1 of these 4 things, colision, mechanical faliure, understeer or oversteer. In GT5D if you start getting oversteer in the untuned car you need to countersteer (steer into the slide) very very quickly, but trying not to over compensate and start a pedulum effect. Normaly you would also power out of the slide at the same time.......Don't! all that happens is the TC kicks in and kills the power, this in turn transfares the weight to the front making the back light and thus have even less traction making the situation even worse! If you don't catch it quick enough then I'm afraid your along for the ride, the problem is a simple one, you gave it too much power.....happens to GT5D players and it happens to F1 drivers racing for the world championship. What it dose show is the superb physics of GT5 and the advances of the weight transfare and tyre physics over GT5P. When the full game hits you'll be able to adjust the car to suit your driving style but until the full release your stuck with a car setup which may not suit everyone but is neserceriy to have a equal playing field for the TT
http://www.youtube.com/watch?v=lvOg2ydEY7Q
http://www.youtube.com/watch?v=7rauHPWAJl4
The last 2 give you an idea of 2 very different cars setup for 2 very different sports.......if the second cars setup was used for the GT5D I think people would quite rightly complain!