Implausibility
I disagree for the most part, but I must agree using the DFP lowers the reality factor of GT4; however I think it is pretty much all of the forcefeed backs fault. The forcefeed back offered by the DFP is a replacement for the feeling of the car. For me it took me about a couple days to figure out drifting in gt4, because honestly it can be compared to real life, not perfect obviously. I find it that I can feel most of the cars weight shifting from the wheel, which you'd normally feel from being pulled in your seat. So in essence that's pretty much what you have to do, use the feeling you get from the wheel to figure out what's going on with the car, along with what's on the screen and it all pulls together.
Well, I know the physics are way off on this game and the flaws show brightly when drifting......and moreso with the DFP.
Too put steering feel in real life simply.....
If the wheel is pushing/pulling to the right, then the car is either gaining angle/tightening turn radious in a left hand turn, loosing angle/opening turn radious in a right hand turn, or taking left hand turn with grip.
If the wheel is neutral, not pushing/pulling at all (in other words you could let go of the wheel and it wouldn't move) then the car is either going in a straight line or not gaining or loosing angle in a turn......this is the "sweet spot" when the car is perfectly balanced. All things like momentum, line, speed, angle, wheelspin all have to be perfect and steady to properly achieve this.
If the wheel is pushing/pulling to the left, then the car is either gaining angle/tightening turn radious in a right hand turn, loosing angle/opening turn radious in a left hand turn, or gripping around a right hand turn.
Sadly this is not true in GT4. Because of GT4's understeer and poor forward bite/traction circle/traction fall off rate, if the wheel is neutral you will have the same affect as pulling to the left in a left hander. If the wheel IS pulling left in a left hander in GT4 it is instant overcorrection in most all circumstances. You have to have the wheel pulling in various amounts of preassure to the opposite direction of the turn to keep balanced or gain angle. It feels like you are 4 wheel drifting all the time (understeer at mid drift). It's very odd.