2009 Saab 9-3 Owner's Manual - Page 175

93_US_MY09.book Page 175 Tuesday, April 15, 2008 10:30 AM Starting and driving 175 Electronic Stability Program ESP® Anti-skid system How the ESP® system works The ESP® system can help to prevent the car from skidding by braking one or several wheels independently of the driver. The engine output is then also reduced to prevent the driving wheels from spinning. The car has sensors that measure wheel speed, yaw rate, lateral acceleration, steering wheel position and braking pressure. The values provided by these sensors are used to calculate the actual direction of the car, the intentions of the driver and whether the ESP® system should be engaged. If this direction does not agree with that intended by the driver, calculated from the steering wheel position, the ESP® system is engaged. The illustration shows how the system brakes one or more wheels (and with varying braking force for each wheel) in order to increase the car's chances of following the direction in which the driver wants to drive. The ESP® system improves the driver's chances of retaining control over the car in a critical situation. WARNING When driving normally, the ESP® system helps to improve the car's stability and maneuverability under slippery road and extreme driving conditions. The ESP® system must not be regarded as a system to enable the driver to maintain higher speeds. The same precautions must be adopted as normal for safe cornering and driving on slippery roads must be adopted. The ESP® system employs both the antilock braking system (ABS) and the traction control system (TCS). It is a system that helps the driver to stabilize the car in unusual circumstances that can otherwise be more difficult to handle.