U.S. Vehicles Are Behind the Curve in Skid Safety
Kat Mastrangelo was driving down a curvy mountain road on hard-packed snow last winter when she hit a patch of ice and felt her Volvo sport utility vehicle start to fishtail. Mastrangelo envisioned her brand new XC90 crashing into oncoming traffic or spinning into a ditch.
None of that happened. Instead of becoming involved in a potentially lethal SUV rollover accident, the Oregon mother of three continued on without incident -- thanks to a computerized stability control system that automatically put her vehicle back on course in the blink of an eye.
But despite almost universal agreement on the life-saving value of electronic stability control, it is rare on cars and trucks in the United States. And some safety experts and consumer advocates say it may be years before they become common on American roads unless the federal government steps in to set standards.
Such systems, widely used in Europe, are considered the next big step forward in auto safety in the U.S., which has concentrated on the construction of better roads and the development of air bags and more crash-worthy cars. The goal is to create vehicles that prevent accidents from happening in the first place.
U.S. automakers, however, have lagged behind their European and Japanese counterparts in embracing electronic stability control technology. Overseas it is standard equipment in a wider range of models.
Instead of agreeing on uniform performance and design standards for the systems, U.S. automakers are taking different approaches under an array of brand names.
Last week, DaimlerChrysler followed Ford and General Motors in announcing that it would make stability control standard equipment on hundreds of thousands of new SUVs. The technology costs $300 to $500 as optional equipment.
Since the rollover problems of SUVs have attracted public attention, manufacturers are concentrating on putting control systems in them instead of making the technology standard in all their vehicles. Studies suggest the systems could also make cars, pickups and minivans much safer, but buyers of those models have to request stability control and pay extra for it.
Mastrangelo became a believer in the technology while on a steep road in her hometown of Bend, Ore. As her Volvo started to skid, sensors triggered a small computer. It automatically cut engine power and selectively applied the brakes to one or more wheels, working faster and more precisely than a human could.
All she had to do was steer where she wanted to go. Her Volvo didn’t even get out of its lane.
“It wasn’t a shimmy,” said Mastrangelo, describing what she felt and heard. “It was like this doonk-doonk-doonk thing. As soon as I was out of it, I said, ‘This car just paid for itself.’ ”
Decades ago, better highway design minimized sharp curves and other hazards. More recently, seat belts and air bags helped to reduce injuries and deaths by protecting occupants during accidents. But electronic stability control can go even further, by avoiding a crash in the first place. As such, it represents a new stage in auto-safety technology.
“We think crash avoidance will be the next frontier, because there aren’t a lot of major safety gains left to be made by making vehicles more crash-worthy,” said Rae Tyson, a spokesman for the National Highway Traffic Safety Administration.
The federal agency has been testing the stability systems but has made no decision on setting a performance standard or requiring automakers to provide the systems. Safety advocates and some industry officials believe the government will ultimately step in.
In a study released this fall, the highway safety agency compared crash statistics for SUVs and other vehicles that had a stability-control system with the experience of identical models that lacked the technology. It found that SUVs with stability control had 63% fewer fatal single-vehicle crashes.
Cars with the systems had 30% fewer such crashes, which include spinouts and rollovers.
Researchers at the Insurance Institute for Highway Safety, a nonprofit testing organization, have estimated that at least 7,000 lives could be saved each year if all vehicles were equipped with stability control systems.
Although stability control has been available on some U.S. models since the late 1990s, fewer than 10% of new vehicles sold here have the systems, compared with about half in Europe.
In the U.S. market, more emphasis has been put on such options as satellite navigation and elaborate sound systems than on stability control equipment.
“This technology is not something the consumer can see or touch, like leather seating,” said William L. Kozyra, president of Continental Teves Inc., a major supplier of the systems. Even for the savvy consumer, shopping for a vehicle with the system can pose a challenge. The technology is marketed under a dizzying assortment of brand names and acronyms. Some consumers may even have the system and not be aware that they do.
Toyota calls its system Vehicle Stability Control and has made it standard on all its SUVs. Mercedes has ESP, which stands for Electronic Stability Program. General Motors offers different systems, including StabiliTrak, Precision Control and Active Traction. Ford has AdvanceTrac with Roll Stability Control.
Behind the brand names are some very real differences in how the systems perform, safety advocates say.
“We don’t yet know which system works the best,” said Susan Ferguson, senior vice president for research at the Insurance Institute for Highway Safety. “Maybe some systems are better than others. We are still at the beginning.”
Consumers Union, which publishes Consumer Reports, has track-tested about 40 vehicles equipped with stability control and found sharp differences: Some react sooner than others; some cut power and apply brakes more forcefully.
“Some are quite intrusive and others let the rear end of the car get out there a bit,” said David Champion, director of automotive testing for Consumers Union.
“We would like the systems to be fairly aggressive when they cut in, but to cut in fairly late so they do not interact with the driver too much.”
Many variables enter into the design of a system. A stability control system for a minivan, for example, might be triggered at a lower threshold than one for a sports car. Even among SUVs, different types of suspension and tires can affect how engineers adjust the system.
Differences in how the systems are engineered have touched off a marketing contest between General Motors and Ford. Both companies recently announced that they were making stability control standard on their most popular SUVs, including the Ford Explorer and the Chevrolet Tahoe.
But Ford said it was going a step further than the competition by adding a gyroscope-type sensor that detects a vehicle roll. That’s the same technology used on Kat Mastrangelo’s Volvo XC90.
All stability control systems have sensors that detect side-to-side movement, steering direction and wheel speed. That helps keep a vehicle going in the direction the driver is steering. But according to Ford, that may not be enough to prevent a rollover in some situations.
“It was from a knowledge of the strengths and weaknesses of the technology that we decided to move forward with roll control,” said Todd Brown, a Ford engineering manager. “We decided to take it to the next step.”
GM officials question whether there is any added benefit from Ford’s approach. Its own system uses a mathematical model to evaluate a stream of data from vehicle sensors and intervene if the driver is at risk of losing control.
“We are just as good as Ford in predicting when the roll is going to occur,” said GM engineer Mario Kennedy. “In our opinion, the way they are using that [gyroscopic] sensor is redundant.”
A road-handling test prescribed by the federal government might settle the issue, said consumer activist Joan Claybrook, president of Public Citizen.
“I have no complaints about the industry taking safety initiatives, but it does seem to me the government has an obligation to take a look at the variety of systems and establish a test for minimum performance,” she said.
For Mastrangelo, the decision to buy an SUV with stability control was prompted by concern for her three children and insights gleaned from her husband’s job. He is a surgeon and handles a lot of trauma cases.
But it was the test drive that convinced her. Her husband tried to get the Volvo to skid, and she was reassured when he failed. “He could not get the thing to spin out,” she said.
