Studies indicate that electronic stability control, shown helping a Chrysler Pacifica make a turn in heavy snow, can reduce the odds of a fatal crash by as much as a third. And it helps a lot in cars as well as SUVs.
This safety feature is so good it's already standard on half the cars sold in the U.S. today. By applying the brakes to individual wheels when sensors detect a loss of control, ESC helps keep your car from spinning into a guardrail (or worse).
On models where it's offered as an option, such as the Mazda 3 and Cadillac CTS, it'll run you an extra $500 or so.
ESC is quickly joining seat belts and ABS as part of the safety triumvirate that every car should have. In five years you won't have a choice: ESC has been slated to be mandatory by 2012.
The Verdict: The best $500 you can spend. If a car you're considering doesn't offer ESC, then reconsider that car.