I must say that this is the main reason I don't play GTPSP that much anymore. I want to experience the best driving physics the game can offer, but the PSP simply doesn't provide the appropriately delicate inputs to control them. I used to play with the D-Pad on the controller from GT1 through to GT4, so it can't be lack of experience.
The Ferrari Enzo is a good example to me, because it is powerful as well as twitchy. With tapping the accelerator when exiting a bend, it's very hard to not unsettle the car and make it spin. The TSC doesn't help either, because even on the highest setting it will not stop wheelspin until the back end of the car is already going. Then, when you need a bit of power to correct the oversteer, TCS drowns your horses completely and you simply spin out.
GTPSP is very realistic for what it is, but for me, it is that very realism that makes high-powered cars pretty unplayable because of the PSP's limited possibilities of controlling them. When I need to dedicate all my efforts to staying on the track instead of driving fast, playing this game is no fun anymore for me.