Not many people know this, but inside most modern cars, there lives a special computer whose sole purpose in life is to prevent crashes. No, not the Blue Screen of Death type of crashing -- the spinning out of control, landing upside down in a ditch and bursting into a fireball type of crashing.
Electronic Stability Program (ESP) is an active safety system which, according to its makers, could prevent up to 80 per cent of all skidding accidents. Bosch says it uses a microcomputer to monitor sensors placed strategically around vehicle. This checks each sensor 25 times per second to see whether the driver's steering input corresponds to the direction in which the vehicle is moving. If the two don't tally, ESP can apply brakes to individual wheels, or apply acceleration to bring the vehicle back on track. We check it out in this video.
ESP also incorporates popular technologies such as ABS anti-lock braking, which stops your wheels from locking up in emergency braking situations, and traction control, which helps you accelerate hard without rubber-burning wheelspin.
All in all, it's pretty flippin' clever and will almost certainly save your life, or at least prevent you from crashing at some point. Next time a car salesman offers you a choice between the optional sunroof or the optional ESP system, choose the latter.