"Electronic stability control is probably the most significant automotive safety technology since the seat belt," says John Woodrooffe of the University of Michigan Transportation Research Institute (UMTRI).Woodrooffe came to that conclusion after conducting the most comprehensive study to date on the benefits of the high-tech system.

According to the UMTRI research, electronic stability control (ESC) reduces the risk of fatal loss-of-control crashes (including rollovers) in sport-utility vehicles by 50 percent. Passenger cars with ESC stand a 30 percent better chance of avoiding such fatal crashes. ESC reduces the risk of similar non-fatal crashes by 70 percent in SUVs and 55 percent in passenger cars.

"The system acts like a guardian angel," says Woodrooffe. When it senses loss of control due to either understeer or oversteer on a curve or turn, it automatically brakes one wheel, reduces the engine power, or both to help the driver regain control. It proves particularly helpful in wet, icy or otherwise slippery conditions.

The federal government's newest rollover ratings seem to reflect UMTRI's conclusions. Pointing to an unprecedented number of ESC-equipped SUVs on the market, the National Highway Traffic Safety Administration notes a dramatic improvement in the number of vehicles earning four stars (placing the chances of a rollover at 13 percent or less). ESC comes as standard equipment on 57 of this year's SUV models and as on option on six others, according to the agency.