yep, got VDC myself.
Yaw control has a lateral acceleration sensor under the front passenger seat which detects lateral (sideways) acceleration or deceleration and teamed with sensors in the steering, wheel speed and brakes, it adjusts the car according to how fast it's going and what the driver's inputs are. Advancetrac basically combines Traction control (slip of wheels in a straight line according to speedometer reading etc) with this ability to measure just how different the car's controls are according to what's actually happening on the road.
Let me paint a picture. Say you've overcooked the corner and you're doing 45pmh into a corner in the wet, you car starts to understeer and you wind on full lock but nothing happens much until you wash off some speed. Well in the case of VDC, it detects the lateral G-forces building up, detects th slip under power through TC and also detects that you're winding on heaps of lock, so it neatly and VERY quickly cuts power via the TC, whilst ABS braking the right wheels to pull you quickly back into line so you can corner neutrally and not understeer. Works the same with oversteer, it will brake wheels individually and cut power as required...
It works like a charm, is absolutely worth the money and in our case (Euro models) is switchable if you just wanna have a little fun...!!) Has saved my bacon once too when I least expected it and by God I swear by it now. Best $990 I ever spent.
2002 Machine Silver Zetec 2.0L, Manual 3 door, ST170 Suspension, 17" ST170 Wheels, ST170 front grille, ST170 interior handles, Genuine Ford Alloy & Leather Gearknob & Handbrake, ST170 clear side indicators, Electric Blue Zetec floor mats