Electronic Stability Control
Expanding on antilock braking systems, an electronic stability system measures the driver's steering input against the car's yaw angle (rotation about the vertical axis) and traction at the wheels. If differences exist, the brakes are applied automatically to a wheel or wheels, which steers the car in the intended direction. If needed, the engine throttle is lowered as well to cease power skids and allow the brakes to do their job.
Individual automakers give their systems names such as Dynamic Stability and Traction Control (Volvo), Dynamic Stability Control (BMW), Electronic Stability Program (Mercedes-Benz and many others), StabiliTrak (GM's brands) and Vehicle Stability Control (Lexus and Toyota), among others. While they're not identical, these trade-named systems all describe the same basic technology.
The Insurance Institute for Highway Safety and National Highway Traffic Safety Administration believe the technology could seriously reduce traffic fatalities. IIHS states that about half of the fatal passenger vehicle crashes that occur each year involve a single vehicle. The IIHS says equipping vehicles with stability control can reduce the risk of involvement in these crashes by nearly 50 percent. It may also reduce the risk of rollovers by more than 70 percent. While a stability system will not specifically detect an impending rollover, it can help prevent conditions that lead to these single-vehicle accidents.
Automakers took notice, offering electronic stability control in about 85 percent of all 2010 vehicles. While 62 percent of pickup trucks do not come with this added feature, it comes standard in all sport utility vehicles — a vehicle category known for a higher percentage of fatal rollover crashes. As SUVs make sharp turns, a higher center of gravity makes them more prone than cars to rollover. While a stability system will not specifically detect an impending rollover, it can help prevent conditions that lead to these single-vehicle accidents.
As of the 2012 model year, Federal Motor Vehicle Safety Standards require electronic stability control systems on passenger vehicles, trucks and buses with a gross vehicle weight rating of 10,000 pounds or less.
To date, only one feature goes a step further than an electronic stability system and actually detects an impending rollover: Roll Stability Control. A Ford Motor Co. system that appeared first on the Volvo XC90 SUV, RSC has spread to other Ford-owned brands and models such as the Ford Expedition and Explorer, and Lincoln MKX and Navigator. Its main advantage is when a vehicle begins to "trip" on a curb, barrier or soft shoulder.
"When you look at the fatality and injury statistics, it's pretty clear that SUVs are a problem. It's good to see that manufacturers, under enormous pressure, are improving."
Speaking generally about SUVs, Consumers for Auto Reliability and Safety founder Rosemary Shahan says, "When you look at the fatality and injury statistics, it's pretty clear that SUVs are a problem. It's good to see that manufacturers, under enormous pressure, are improving."
GM spokesman Adam Adler says the automaker has been looking into the need for this technology for years and began by including electronic stability systems in 1997 on several Cadillac models. That's no surprise, as most new technologies arrive first on higher-end models before trickling down to the rest of the lineup. This is largely because new technologies are often expensive, which is less of an issue for a luxury purchaser than a typical buyer.
While most of the automobile world is upbeat about electronic stability control, occasional gripes emanate from enthusiasts who fret that the automated technology overrides the high-performance maneuvers they like to perform, such as cornering at rapid speeds.
"There are some complaints from drivers who like to be more on the edge and feel their car lose it a little bit and then steer back into it themselves," says Adrian Lund, chief operating officer of IIHS. "And the electronic stability control does take that away. For most of us though, who are just trying to get from A to B safely, that's a good thing."
Some automakers attempt to accommodate their customers, calibrating their stability systems to match the nature of their sportier cars or by allowing them to turn electronic stability control off.
Despite enthusiasts' protest, all new vehicles now have standard electronic stability control. NHTSA estimates electronic stability control is going to save 5,300 to 9,600 lives and prevent 156,000 to 238,000 injuries in all types of crashes annually.