Big sport-utility vehicles and pickups may be more popular than ever, but if you bothered to ask, most Americans would admit to some reservations about driving them. There's the lingering rollover worry, for one thing. Then there's the trauma that goes along with parking one of these behemoths at a crowded shopping mall. You've seen them: Frustrated drivers in Chevy Suburbans failing to squeeze into parking spaces between two lesser SUVs and finally parking in a deserted part of the lot.
Now, General Motors (GM
) is starting to equip its biggest trucks and SUVs with four-wheel steering technology that makes parking those big rigs--even parallel-parking them--a cinch. More important, the so-called Quadrasteer technology, developed by former GM subsidiary Delphi (DPH
), comes with huge safety payoffs. The innovation, which combines conventional front-wheel steering with an electrically powered rear-wheel steering system, increases stability when towing a boat or motor home, cutting down on dangerous trailer swaying. And it improves handling in high-speed maneuvers, such as sudden lane changes, reducing the rollover risk.
Four-wheel steering could be "game-changing" technology, says Sanford C. Bernstein analyst Scott Hill, as important as four-wheel-drive transmissions or antilock brakes. Currently available only as standard equipment on GM's $44,100, top-of-the-line Sierra Denali pickup, the technology will be offered later this year as a $4,500 option on 2003 models of other heavy-duty pickups and the Suburban and Yukon XL full-size SUVs.
Other manufacturers are sure to follow, says Hill, who thinks four-wheel steering could be on as many as 1.7 million trucks by 2008. "The potential is there," concurs James Hall, an analyst for Tustin (Calif.) research firm AutoPacific Group. "But the price has to come down." Other industry watchers are certain that will happen as volume increases. The potential demand is "huge," says Gary Cowger, president of GM North America. "Once you drive it, you get it."
Indeed, it's tough to grasp everything Quadrasteer offers until you get behind the wheel of a Suburban or an extended-cab pickup. I was skeptical of Delphi's claim that four-wheel steering gives the mammoth Suburban nearly the turning radius of a compact Honda Civic. Then I tried a few doughnut turns in an empty parking lot, first with Quadrasteer switched off and then with it on. The result was amazing: Quadrasteer shaved nearly 10 feet off the Suburban's turning circle. Sliding into a tight parking space was a breeze. It made me wonder why no one had thought of this before.
In fact, four-wheel steering systems aren't new. The Honda Prelude was among a handful of small Asian cars that offered the feature in the mid-1980s. The technology didn't catch on with consumers, though, in part because mechanical systems back then were inferior to today's electronic "steer-by-wire" systems. But the biggest reason was that four-wheel steering really wasn't necessary on a small car that already was fairly nimble. But today, America's love affair with big trucks and SUVs is giving four-wheel steering a second chance.
With the Quadrasteer system, sensors that detect the position of the steering wheel and the speed of the vehicle send signals to a control unit, which uses algorithms to determine the appropriate angle of the rear wheels. At lower speeds, the rear wheels turn in the opposite direction of the front wheels. This allows for better maneuverability while parking or, say, backing into a boat launch. At higher speeds, all the wheels turn in the same direction, reducing the vehicle's rolling motion that sometimes causes drivers to lose control when swerving. Instead, the vehicle will tend to slide sideways, making it easier to handle. Such added safety and convenience are welcome, and with demand for big SUVs showing no signs of a letup, four-wheel steering should quickly win converts.
By Joann Muller
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Copyright 2002 , by The McGraw-Hill Companies Inc. All rights reserved.
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