DEARBORN, MI — Ford Motor Co. announced on May 2 that the 2006 models of its E-Series extended wagons are now fitted with AdvanceTrac and Roll Stability Control (RSC). These systems combine inputs from the wheel rotation sensors already in the ABS antilock braking system with a yaw control sensor and a roll-motion gyroscopic sensor to help the driver bring the vehicle under control in adverse driving conditions. Both systems can reduce the risk to driver and passengers if the vehicle loses stability. In the ABS system, the wheel sensors tell the ABS controller that a wheel is sliding instead of rotating, and the system then pulses the brake pressure to allow the wheel to continue rotating. Since a sliding wheel cannot be steered, ensuring that all wheels are rotating allows the driver to continue to steer the vehicle. The AdvanceTrac traction-control system works in the reverse of the ABS system. When the controller determines that one rear wheel is rotating faster than the other, it applies the brakes on that wheel to keep it from spinning. With yaw control, the sensors determine if the vehicle is going in the direction the driver is steering it, or if it is understeering or oversteering. In understeer, the front end of the vehicle tends to slide toward the outside of a curve. In oversteer, the rear end of the vehicle tends to slide to the outside of a curve. In both of these situations, the controller applies a single brake on the front or rear end to bring the vehicle back into the desired line. Finally, with RSC, the sensors can determine if a rollover is imminent, and use the capabilities of the AdvanceTrac system to make sure all four wheels stay on the ground.