Electronic stability control (ESC) — called ESP by Mercedes-Benz and Bosch — helps prevent skids and loss of control by braking individual wheels and reducing engine power when the car starts to slide. It debuted on the Mercedes-Benz S 600 Coupé in 1995, became famous after the 1997 “moose test” rollover of the Mercedes A-Class, and is now mandatory on new passenger vehicles in the U.S. (fully phased in by the 2012 model year) and in many other countries. Safety researchers consider it one of the most effective safety technologies since the seat belt.

At a glance
Debut 1995, Mercedes-Benz S 600 Coupé (with Bosch)
Other names ESP, VSC, DSC, StabiliTrak, VDC
Mandatory in U.S. All new light vehicles by the 2012 model year
Built on ABS and traction control hardware

How it works

ESC compares where the driver is steering with where the car is actually going, using sensors for steering angle, yaw rate (rotation) and sideways acceleration. If the car starts to oversteer (the rear slides) or understeer (the front plows wide), it brakes specific wheels to rotate the car back onto the intended path.

The moose test

In 1997, Swedish journalists performing a sudden avoidance maneuver — the “moose test” — tipped over the new Mercedes A-Class. Mercedes responded by making ESP standard on the A-Class, which dramatically accelerated its adoption across the industry.

Why it matters

ESC is especially effective at preventing single-vehicle crashes and rollovers, notably in taller vehicles like SUVs. Read ABS history and S-Class safety firsts.

Winter driving

On icy or snowy roads in the Northeast, ESC and all-wheel drive work together to maintain stability. But they can’t overcome physics — speed and tires matter most. Read AWD vs 4WD.