Starting in September, 2003, Toyota Motor Corp. will equip all of its SUVs, including the new entry-level RAV4, with electronic stability control systems. The devices, known by a variety of brand names, intervene to prevent the type of skidding that often precedes deadly rollovers. Because of their high center of gravity, SUVs are more prone to rollovers than cars that ride lower to the ground. Each year, rollovers account for about a quarter of U.S. fatalities and more than half of SUV occupant fatalities. Luxury SUVs sold by Mercedes-Benz and BMW have long been fitted with the feature. Now Toyota is upping the ante by providing them as standard equipment on an SUV priced under $20,000. Toyota spokesman John Hanson said the company has extended vehicle stability control across its SUV range to generate economies of scale. Produced by Bosch GmbH, Continental Teves, TRW and other electronics specialists, the devices rely on sensors to detect whether a driver is losing control, usually because the car is swerving too fast. The system applies the brake to one or more wheels, and can even slow the engine, to steady the vehicle.