Phasing in during Model Year 2010 and required MY2012,

The FMVSS regulation defines ESC as being capable of applying brake torque individually to any of the four wheels and possibly reducing engine torque through a control algorithm intended to maintain lateral stability; that is, to mitigate excessive under- or oversteer.

The performance requirements of FMVSS 126 are quite technical. One second after completion of a sine-with-dwell steering input of 0.7-second periodicity, the car cannot exceed 35 percent of its initial peak value of yaw rate; 0.75 sec. later, it must not exceed 20 percent. Simply stated, this means ESC must mitigate lateral forces after the steering is moved from side to sides. Uncontrolled, extreme oversteer would take the car across the road, possibly backward. Instead, sensing this larger rear arc, ESC applies braking to the left front wheel, the heavily loaded outer one, thus imparting a force that counteracts the rear behavior and stabilizes the car's attitude.

In a similar right-hand turn if a car displays extreme understeer, the front wheels are traveling an arc larger than the one being steered. Uncontrolled, the car would leave its lane, front-end first. Instead, ESC intervenes by applying the right rear brake, the inner one, again stabilizing the car's attitude.

Either of these braking interventions is usually accompanied by a reduction of engine torque, the car's slower speed enhancing stability and minimizing diversion from the intended path. What's more, these interventions all occur in milliseconds.

Below is a comparison chart by "Road and Track" highlighting six recent ESC systems.

A SELECTION OF ELECTRONIC STABILITY CONTROL SYSTEMS
Vehicle Model	Device	Strategies	Modes	Indicators	Remarks 1
BMW X6	DPC, Dynamic Performance Control xDrive all-wheel drive DSC, Dynamic Stability Control; DTC, Dynamic Traction Control	Rear left/right torque split Front/rear torque split Selective braking, torque reduction, steering correction (opt.)	Continuous Continuous On, Dynamic Traction Control Off , DSC/DTCOff	Torque-split gauge,fore/aft & front/rear DSCActive, DTCWarning, Off	DSCis invoked only at extremes; xDrive and DP act more subtly at lower thresholds of intervention. Active Steering (variable-ratio) is optional.
Chevrolet Corvette	Active Handling	Selective braking, torque reduction	On, Traction Control Off, Competitive Driving, Off	Mode indicators, Active note in message center	Braking reduced at inner rear wheel in heavy lateral g.
Mercedes-Benz C63 AMG	ESP, Electronic Stability Program	Selective braking, torque reduction	ESP On, ESP Sport, ESP Off	Active icon, Off warning	Braking restores ESP On; release returns chosen mode.
Mitsubishi Lancer Evolution X	S-AWC, Super All Wheel Control	Selective braking, torque reduction, fore/aft torque split, rear left/right torque split	ASC: Off Tarmac, Gravel, Snow (AYC/ACDmodes)	S-AWCactivity level, ASCOff icon, ASCOff warning	S-AWCintegrally manages ASC, AYC, ACDand ABS.
Nissan GT-R	VDC-R, Vehicle Dynamic Control High-Performance	Selective braking, torque reduction, fore/aft torque split (R mode)	Sport, R (high-performance), Off	Display panel information	R adds Yaw-rate Feedback Control varying fore/aft torque split.
Scion xB	VSC, Vehicle Stability Control	Selective braking, torque reduction	On; VSC/TRACOff	Active icon, VSCOff warning	Audible warning of incipient loss of grip.
1 Note: All get wheel speed and brake pressure input from ABS systems. Alo, inputs of lateral g, yaw rate and steering angle are common to all.

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