How Does Electronic Stability Control Work (and Why it's Important)

January 27, 2012

Found on most luxury vehicles as well as in increasing frequency among the more moderately priced models, stability control is an essential technology that can vastly increase driver safety, especially in inclement weather. While stability control is somewhat of a catch-all term, there are several different manners in which a stability control system can work.

Throttle Based Stability Control

This method of dynamic stability control uses an electronic throttle and careful observation of wheel spin in order to prevent over steer in rear wheel drive vehicles, and under steer in front wheel drive models. This type of stability control is particularly useful for wet or icy conditions in high powered rear wheel drive vehicles, as well as for countering torque steer in high powered front wheel drive vehicles. For all wheel drive vehicles with active center differentials, front and rear torque delivery ratios may also be altered to preserve stability and reduce wheel spin.

Braking Based Stability Control

Stability control systems using braking force to stabilize the vehicle tend to be found on vehicles with all wheel drive and active center differentials such as the Mitsubishi Lancer Evolution. This type of electric stability control measures wheel spin on all four wheels in addition to steering wheel angle and throttle input. It will apply slight braking force at each of the four wheels as needed, to either prevent over steer or under steer, and allow the vehicle to be as neutral as possible during cornering. It should be noted that this type of stability control is often times used in conjunction with throttle based control systems in order to give superior control and handling regardless of road surface and weather conditions.

Why Stability Control is Important

Stability control seems to serve its greatest role as a safety device in powerful rear wheel drive vehicles. When excessive power is applied to a rear wheel drive vehicle when cornering, the vehicle will over steer and usually spin. While this can be a welcome behavior for a seasoned race driver, for the average driver, this can lead to an accident should it come unexpectedly. Especially when in traffic. This spinning is generally caused when the rear wheels lose traction. Either due to power overwhelming available grip, or due to ice or hydroplaning that causes a sudden and unexpected loss of traction at the rear wheels. Because of the quick response time of most stability control systems, this loss of traction can be anticipated, and throttle reduced before traction is overwhelmed, helping to prevent a spin and maintain full control of the vehicle.

While stability control can lead to increased safety for normal drivers in normal driving environments, it does garner criticism from professional drivers due to its unnatural feel and prohibitively stabilizing effects. For someone used to performance-oriented driving and handling, this aversion to over steer can make a vehicle feel sluggish and unresponsive. For normal drivers, especially those who drive in areas with harsh and unpredictable weather, the greatly reduced chances of an accident may be worth the penalty to agility, especially if the driver lacks experience.

Related Questions and Answers

Do I Have to Pay Extra for a Vehicle Stability Control System?

A vehicle stability system is standard on some vehicles, and offered as an option on others. It really depends on the car. Luxury vehicles are normally equipped with a vehicle stability system as a standard option. Vehicle stability control has also moved into mid-range cars. Coming standard on many models but offered as an option on others. When you move into the sub-compact models, vehicle stability systems are rarely standard. It is often available as an option, but on some models it is not available at all. The price of VSC systems vary, but expect to pay between $250-$1,000 depending on the car.

Are Electronic Stability Control Systems Standard for All New Cars?

Electronic stability control systems are not standard on all new cars. It varies depending on the type of vehicle you are buying. Luxury vehicles and high end sports cars almost always come with electronic stability systems standard. Over the years, electronic stability control systems have also become standard on many mid-range cars, SUVs and pick-up trucks. When you move into the sub-compact range of cars, you will rarely find electronic stability control systems standard. They are often offered as an option on the more sporty trim levels. In many cases, stability control is not available at all. Electronic stability control systems are not really available as third party aftermarket add-ons.

Is an Electronic Stability System and Vehicle Traction Control the Same Thing?

An electronic stability system is not the same as a traction control system. While they are similar, there are significant differences. An electronic stability control system can do the job of a traction control system. A traction control system cannot do the same thing an ESS can do. Traction control can sense a wheel slip and applies the brakes or cuts the engine power to regain traction. An ESS system is more sensitive to wheel slip and will start the correction sooner. It can also brake each individual wheel, which means it can regain control of the vehicle in situations where a human or a traction control system couldn't.

Are (ABS) Anti-Lock Braking Systems Standard in All New Cars?

ABS, or, an anti-lock braking system are not currently standard on all new cars. They are installed standard on about 90% of vehicles sold in the US. In 2011, the government will require that all vehicles sold in the United States have an electronic stability control system installed as standard. These systems are built on top of the ABS system, so anti-lock systems will become standard on all cars in the next year or two. ABS systems are standard on all luxury and mid-size cars these days. When you get into the sub-compact models, ABS is not always standard, but is offered as an option on all models and trim levels.

What is the Average Cost of an ESP Electronic Stability Add On?

An ESP electronic stability control system comes standard on many vehicles these days. The majority of luxury vehicles have electronic stability standard, as do many mid-range vehicles. It is only when you get down to compacts and sub-compacts that electronic stability systems are optional or not available at all. The government is requiring that all vehicles have an electronic stability control system standard starting in 2011. When an ESP system is added as an option, the cost will vary depending on the vehicle. You should budget between $250-$1,000. Electronic stability systems must be added as an option when you are purchasing the vehicle new. There are currently no aftermarket add-on ESP systems.